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Lucidi M, Visaggio D, Migliaccio A, Capecchi G, Visca P, Imperi F, Zarrilli R. Pathogenicity and virulence of Acinetobacter baumannii: Factors contributing to the fitness in healthcare settings and the infected host. Virulence 2024; 15:2289769. [PMID: 38054753 PMCID: PMC10732645 DOI: 10.1080/21505594.2023.2289769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 11/27/2023] [Indexed: 12/07/2023] Open
Abstract
Acinetobacter baumannii is a common cause of healthcare-associated infections and hospital outbreaks, particularly in intensive care units. Much of the success of A. baumannii relies on its genomic plasticity, which allows rapid adaptation to adversity and stress. The capacity to acquire novel antibiotic resistance determinants and the tolerance to stresses encountered in the hospital environment promote A. baumannii spread among patients and long-term contamination of the healthcare setting. This review explores virulence factors and physiological traits contributing to A. baumannii infection and adaptation to the hospital environment. Several cell-associated and secreted virulence factors involved in A. baumannii biofilm formation, cell adhesion, invasion, and persistence in the host, as well as resistance to xeric stress imposed by the healthcare settings, are illustrated to give reasons for the success of A. baumannii as a hospital pathogen.
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Affiliation(s)
- Massimiliano Lucidi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | | | | | - Paolo Visca
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Francesco Imperi
- Department of Science, Roma Tre University, Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Santa Lucia Foundation IRCCS, Rome, Italy
| | - Raffaele Zarrilli
- Department of Public Health, University of Naples Federico II, Naples, Italy
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Rajangam SL, Narasimhan MK. Current treatment strategies for targeting virulence factors and biofilm formation in Acinetobacter baumannii. Future Microbiol 2024; 19:941-961. [PMID: 38683166 DOI: 10.2217/fmb-2023-0263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 03/20/2024] [Indexed: 05/01/2024] Open
Abstract
A higher prevalence of Acinetobacter baumannii infections and mortality rate has been reported recently in hospital-acquired infections (HAI). The biofilm-forming capability of A. baumannii makes it an extremely dangerous pathogen, especially in device-associated hospital-acquired infections (DA-HAI), thereby it resists the penetration of antibiotics. Further, the transmission of the SARS-CoV-2 virus was exacerbated in DA-HAI during the epidemic. This review specifically examines the complex interconnections between several components and genes that play a role in the biofilm formation and the development of infections. The current review provides insights into innovative treatments and therapeutic approaches to combat A. baumannii biofilm-related infections, thereby ultimately improving patient outcomes and reducing the burden of HAI.
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Affiliation(s)
- Seetha Lakshmi Rajangam
- Department of Genetic Engineering, School of Bioengineering, College of Engineering & Technology, SRM Institute of Science & Technology, Kattankulathur, Chennai, Tamil Nadu, 603203, India
| | - Manoj Kumar Narasimhan
- Department of Genetic Engineering, School of Bioengineering, College of Engineering & Technology, SRM Institute of Science & Technology, Kattankulathur, Chennai, Tamil Nadu, 603203, India
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Singh S, Singh S, Trivedi M, Dwivedi M. An insight into MDR Acinetobacter baumannii infection and its pathogenesis: Potential therapeutic targets and challenges. Microb Pathog 2024; 192:106674. [PMID: 38714263 DOI: 10.1016/j.micpath.2024.106674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 04/22/2024] [Accepted: 05/01/2024] [Indexed: 05/09/2024]
Abstract
Acinetobacter baumannii is observed as a common species of Gram-negative bacteria that exist in soil and water. Despite being accepted as a typical component of human skin flora, it has become an important opportunistic pathogen, especially in healthcare settings. The pathogenicity of A. baumannii is attributed to its virulence factors, which include adhesins, pili, lipopolysaccharides, outer membrane proteins, iron uptake systems, autotransporter, secretion systems, phospholipases etc. These elements provide the bacterium the ability to cling to and penetrate host cells, get past the host immune system, and destroy tissue. Its infection is a major contributor to human pathophysiological conditions including pneumonia, bloodstream infections, urinary tract infections, and surgical site infections. It is challenging to treat infections brought on by this pathogen since this bacterium has evolved to withstand numerous drugs and further emergence of drug-resistant A. baumannii results in higher rates of morbidity and mortality. The long-term survival of this bacterium on surfaces of medical supplies and hospital furniture facilitates its frequent spread in humans from one habitat to another. There is a need for urgent investigations to find effective drug targets for A. baumannii as well as designing novel drugs to reduce the survival and spread of infection. In the current review, we represent the specific features, pathogenesis, and molecular intricacies of crucial drug targets of A. baumannii. This would also assist in proposing strategies and alternative therapies for the prevention and treatment of A. baumannii infections and their spread.
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Affiliation(s)
- Sukriti Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Sushmita Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Mala Trivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India; Research Cell, Amity University Uttar Pradesh, Lucknow, 226028, India.
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Amini MS, Baseri Salehi M, Bahador N. Evaluating the antibacterial effect of meropenem-loaded chitosan/sodium tripolyphosphate (TPP) nanoparticles on Acinetobacter baumannii isolated from hospitalized patients. BMC Infect Dis 2024; 24:631. [PMID: 38914964 PMCID: PMC11197314 DOI: 10.1186/s12879-024-09522-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 06/17/2024] [Indexed: 06/26/2024] Open
Abstract
BACKGROUND Acinetobacter baumannii is a health threat due to its antibiotic resistance. Herein, antibiotic susceptibility and its association with the Toxin-antitoxin (TA) system genes in A. baumannii clinical isolates from Iran were investigated. Next, we prepared meropenem-loaded chitosan nanoparticles (MP-CS) and investigated their antibacterial effects against meropenem-susceptible bacterial isolates. METHODS Out of 240 clinical specimens, 60 A. baumannii isolates were assessed. Antibiotic resistance of the isolates against conventional antibiotics was determined alongside investigating the presence of three TA system genes (mazEF, relBE, and higBA). Chitosan nanoparticles were characterized in terms of size, zeta potential, encapsulation efficiency, and meropenem release activity. Their antibacterial effects were assessed using the well diffusion method, minimum inhibitory concentration (MIC), and colony-forming unit (CFU) counting. Their cytotoxic effects and biocompatibility index were determined via the MTT, LDH, and ROS formation assays. RESULTS Ampicillin, ceftazidime, and colistin were the least effective, and amikacin and tobramycin were the most effective antibiotics. Out of the 60 isolates, 10 (16.7%), 5 (8.3%), and 45 (75%) were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. TA system genes had no significant effect on antibiotic resistance. MP-CS nanoparticles demonstrated an average size of 191.5 and zeta potential of 27.3 mV alongside a maximum encapsulation efficiency of 88.32% and release rate of 69.57%. MP-CS nanoparticles mediated similar antibacterial effects, as compared with free meropenem, against the A. baumannii isolates with significantly lower levels of meropenem. MP-CS nanoparticles remarkably prevented A549 and NCI-H292 cell infection by the A. baumannii isolates alongside demonstrating a favorable biocompatibility index. CONCLUSION Antibiotic-loaded nanoparticles should be further designed and investigated to increase their antibacterial effect against A. baumannii and assess their safety and applicability in vivo settings.
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Affiliation(s)
- Marziyeh Sadat Amini
- Department of Microbiology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran
| | - Majid Baseri Salehi
- Department of Microbiology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran.
| | - Nima Bahador
- Department of Microbiology, Shiraz Branch, Islamic Azad University, Shiraz, Iran
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Cheewapat R, Redkimned J, Lekuthai S, Kitti T, Tasanapak K, Thanwisai A, Sitthisak S, Sornda T, Impheng H, Onsurathum S, Leungtongkam U, Lamlertthon S, Kucharoenphaibul S, Wongwigkarn J, Singkum P, Chanchaithong P, Thummeepak R. Genomic Landscape Reveals Chromosomally-Mediated Antimicrobial Resistome and Virulome of a High-Risk International Clone II Acinetobacter baumannii AB073 from Thailand. Glob Health Epidemiol Genom 2024; 2024:8872463. [PMID: 38716477 PMCID: PMC11074871 DOI: 10.1155/2024/8872463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 03/14/2024] [Accepted: 04/18/2024] [Indexed: 07/28/2024] Open
Abstract
This study utilized integrative bioinformatics' tools together with phenotypic assays to understand the whole-genome features of a carbapenem-resistant international clone II Acinetobacter baumannii AB073. Overall, we found the isolate to be resistant to seven antibiotic classes, penicillins, β-lactam/β-lactamase inhibitor combinations, cephalosporins, carbapenems, aminoglycosides, fluoroquinolones, and folate pathway antagonists. These resistance phenotypes are related to various chromosomal-located antibiotic resistance determinants involved in different mechanisms such as reduced permeability, antibiotic target protection, antibiotic target alteration, antibiotic inactivation, and antibiotic efflux. IC2 A. baumannii AB073 could not transfer antibiotic resistance by conjugation experiments. Likewise, mobilome analysis found that AB073 did not carry genetic determinants involving horizontal gene transfer. Moreover, this isolate also carried multiple genes associated with the ability of iron uptake, biofilm formation, immune invasion, virulence regulations, and serum resistance. In addition, the genomic epidemiological study showed that AB073-like strains were successful pathogens widespread in various geographic locations and clinical sources. In conclusion, the comprehensive analysis demonstrated that AB073 contained multiple genomic determinants which were important characteristics to classify this isolate as a successful international clone II obtained from Thailand.
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Affiliation(s)
- Rattiya Cheewapat
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Jadsadaporn Redkimned
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Sirikran Lekuthai
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Thawatchai Kitti
- Department of Oriental Medicine, Chiang Rai College, Chiang Rai 57000, Thailand
| | - Kannipa Tasanapak
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Aunchalee Thanwisai
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Sutthirat Sitthisak
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Thanet Sornda
- Department of Biochemistry, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Hathaichanok Impheng
- Department of Physiology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Sudarat Onsurathum
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Udomluk Leungtongkam
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Supaporn Lamlertthon
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Siriwat Kucharoenphaibul
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Jintana Wongwigkarn
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
| | - Pantira Singkum
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Salaya 10400, Thailand
| | - Pattrarat Chanchaithong
- Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Rapee Thummeepak
- Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
- Centre of Excellence in Medical Biotechnology, Faculty of Medical Science, Naresuan University, Phitsanulok 65000, Thailand
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Yang T, Zou Y, Ng HL, Kumar A, Newton SM, Klebba PE. Specificity and mechanism of TonB-dependent ferric catecholate uptake by Fiu. Front Microbiol 2024; 15:1355253. [PMID: 38601941 PMCID: PMC11005823 DOI: 10.3389/fmicb.2024.1355253] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 01/23/2024] [Indexed: 04/12/2024] Open
Abstract
We studied the Escherichia coli outer membrane protein Fiu, a presumed transporter of monomeric ferric catecholates, by introducing Cys residues in its surface loops and modifying them with fluorescein maleimide (FM). Fiu-FM bound iron complexes of the tricatecholate siderophore enterobactin (FeEnt) and glucosylated enterobactin (FeGEnt), their dicatecholate degradation product Fe(DHBS)2 (FeEnt*), the monocatecholates dihydroxybenzoic acid (FeDHBA) and dihydroxybenzoyl serine (FeDHBS), and the siderophore antibiotics cefiderocol (FDC) and MB-1. Unlike high-affinity ligand-gated porins (LGPs), Fiu-FM had only micromolar affinity for iron complexes. Its apparent KD values for FeDHBS, FeDHBA, FeEnt*, FeEnt, FeGEnt, FeFDC, and FeMB-1 were 0.1, 0.7, 0.7, 1.0, 0.3, 0.4, and 4 μM, respectively. Despite its broad binding abilities, the transport repertoires of E. coli Fiu, as well as those of Cir and FepA, were less broad. Fiu only transported FeEnt*. Cir transported FeEnt* and FeDHBS (weakly); FepA transported FeEnt, FeEnt*, and FeDHBA. Both Cir and FepA bound FeGEnt, albeit with lower affinity. Related transporters of Acinetobacter baumannii (PiuA, PirA, BauA) had similarly moderate affinity and broad specificity for di- or monomeric ferric catecholates. Both microbiological and radioisotopic experiments showed Fiu's exclusive transport of FeEnt*, rather than ferric monocatecholate compounds. Molecular docking and molecular dynamics simulations predicted three binding sites for FeEnt*in the external vestibule of Fiu, and a fourth site deeper in its interior. Alanine scanning mutagenesis in the outermost sites (1a, 1b, and 2) decreased FeEnt* binding affinity as much as 20-fold and reduced or eliminated FeEnt* uptake. Finally, the molecular dynamics simulations suggested a pathway of FeEnt* movement through Fiu that may generally describe the process of metal transport by TonB-dependent receptors.
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Affiliation(s)
| | | | | | | | | | - Phillip E. Klebba
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States
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Maure A, Robino E, Van der Henst C. The intracellular life of Acinetobacter baumannii. Trends Microbiol 2023; 31:1238-1250. [PMID: 37487768 DOI: 10.1016/j.tim.2023.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 07/26/2023]
Abstract
Acinetobacter baumannii is a Gram-negative opportunistic bacterium responsible for nosocomial and community-acquired infections. This pathogen is globally disseminated and associated with high levels of antibiotic resistance, which makes it an important threat to human health. Recently, new evidence showed that several A. baumannii isolates can survive and proliferate within eukaryotic professional and/or nonprofessional phagocytic cells, with in vivo consequences. This review provides updated information and describes the tools that A. baumannii possesses to adhere, colonize, and replicate in host cells. Additionally, we emphasize the high genetic and phenotypic heterogeneity detected amongst A. baumannii isolates and its impact on the bacterial intracellular features. We also discuss the need for standardized methods to characterize this pathogen robustly and consequently consider some strains as facultative intracellular bacteria.
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Affiliation(s)
- Alexandra Maure
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Etienne Robino
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Charles Van der Henst
- Microbial Resistance and Drug Discovery, VIB-VUB Center for Structural Biology, VIB, Flanders Institute for Biotechnology, Brussels, Belgium; Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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8
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Gamit HA, Amaresan N. Methylobacterium spp. mitigation of UV stress in mung bean (Vigna radiata L.). Photochem Photobiol Sci 2023; 22:2839-2850. [PMID: 37838625 DOI: 10.1007/s43630-023-00490-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 09/29/2023] [Indexed: 10/16/2023]
Abstract
Methylotrophs are a diverse group of bacteria that abundantly colonize the phyllosphere and have great potential to withstand UV irradiation because of their pigmented nature and ability to promote plant growth through various mechanisms. The present study investigated the effects of UVB radiation on plant growth-promoting (PGP) properties of methylotrophic bacteria and the growth of Vigna radiata L. A total of 55 methylotrophic bacteria were isolated from desert plants, and 15 methylotrophs were resistant to UVB radiation for 4 h. All UVB-resistant methylotrophs possess a methyldehydrogenase gene. Identification based on 16S rRNA gene sequencing revealed that all 15 UVB-resistant methylotrophs belonged to the genera Methylorubrum (07), Methylobacterium (07), and Rhodococcus (01). Screening of methylotrophs for PGP activity in the presence and absence of UVB radiation revealed that all isolates showed ACC deaminase activity and growth on a nitrogen-free medium. Furthermore, the production of IAA-like substances ranged from 8.62 to 85.76 µg/mL, siderophore production increased from 3.47 to 65.75% compared to the control. Seed germination assay with V. radiata L. (mung bean) exposed to UVB radiation revealed that methylotrophs improved seed germination, root length, and shoot length compared to the control. The present findings revealed that the isolates SD3, SD2, KD1, KD5, UK1, and UK3 reduced the deleterious effects of UVB radiation on mung bean plants and can be used to protect seedlings from UVB radiation for sustainable agriculture.
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Affiliation(s)
- Harshida A Gamit
- C. G. Bhakta Institute of Biotechnology, Uka Tarsadia University, Maliba Campus, Bardoli, Surat, 394 350, Gujarat, India
| | - Natarajan Amaresan
- C. G. Bhakta Institute of Biotechnology, Uka Tarsadia University, Maliba Campus, Bardoli, Surat, 394 350, Gujarat, India.
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McGuffey JC, Jackson-Litteken CD, Di Venanzio G, Zimmer AA, Lewis JM, Distel JS, Kim KQ, Zaher HS, Alfonzo J, Scott NE, Feldman MF. The tRNA methyltransferase TrmB is critical for Acinetobacter baumannii stress responses and pulmonary infection. mBio 2023; 14:e0141623. [PMID: 37589464 PMCID: PMC10653896 DOI: 10.1128/mbio.01416-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 07/10/2023] [Indexed: 08/18/2023] Open
Abstract
IMPORTANCE As deficiencies in tRNA modifications have been linked to human diseases such as cancer and diabetes, much research has focused on the modifications' impacts on translational regulation in eukaryotes. However, the significance of tRNA modifications in bacterial physiology remains largely unexplored. In this paper, we demonstrate that the m7G tRNA methyltransferase TrmB is crucial for a top-priority pathogen, Acinetobacter baumannii, to respond to stressors encountered during infection, including oxidative stress, low pH, and iron deprivation. We show that loss of TrmB dramatically attenuates a murine pulmonary infection. Given the current efforts to use another tRNA methyltransferase, TrmD, as an antimicrobial therapeutic target, we propose that TrmB, and other tRNA methyltransferases, may also be viable options for drug development to combat multidrug-resistant A. baumannii.
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Affiliation(s)
- Jenna C. McGuffey
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Clay D. Jackson-Litteken
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Gisela Di Venanzio
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Aubree A. Zimmer
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Jessica M. Lewis
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Jesus S. Distel
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | - Kyusik Q. Kim
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Hani S. Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Juan Alfonzo
- Department of Microbiology and The Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Nichollas E. Scott
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Mario F. Feldman
- Department of Molecular Microbiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
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Mansouri M, Sadeghpoor M, Jahangiri A, Ghaini MH, Rasooli I. Enhanced immunoprotection against Acinetobacter baumannii infection: Synergistic effects of Bap and BauA in a murine model. Immunol Lett 2023; 262:18-26. [PMID: 37652189 DOI: 10.1016/j.imlet.2023.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/26/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND The rise of multi-drug resistant Acinetobacter baumannii poses a grave threat to hospital settings, resulting in increased mortality rates and garnering global attention. The formation of biofilms facilitated by biofilm-associated protein (Bap) and the iron absorption capabilities mediated by Baumannii acinetobactin utilization A (BauA) contribute to the persistence and survival of multidrug-resistant strains. In this study, we aimed to investigate the potential of disrupting the function of BauA and Bap simultaneously as a strategy for controlling A. baumannii. METHODS Recombinant Bap and BauA were expressed, purified, and subcutaneously administered individually and in combination to BALB/c mice. Subsequently, mice were intraperitoneally challenged with A. baumannii, and the bacterial load and tissue damage in the spleen, lung, and liver were assessed. Serum samples were evaluated to determine antibody titers in surviving mice. RESULTS Specific IgG antibodies were significantly increased. A combination of the antigens resulted in enhanced titer of specific IgGs in comparison to either BauA or Bap alone. The antibodies remained stable over a seven-month period. The combination of Bap and BauA exhibited superior immunoprotection against A. baumannii infection compared to individual administration, resulting in a further reduction in bacterial load in the liver, spleen, and lungs. The histopathological analysis demonstrated successful protection of the tissues against A. baumannii-induced damage upon administration of the two immunogens. CONCLUSIONS The combination of Bap and BauA has the potential to target a broader range of A. baumannii strains, including those expressing either Bap or BauA, thereby increasing its efficacy against a diverse array of strains.
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Affiliation(s)
| | | | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems biology and poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | | | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
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Mirali M, Jahangiri A, Jalali Nadoushan M, Rasooli I. A two-protein cocktail elicits a protective immune response against Acinetobacter baumannii in a murine infection model. Microb Pathog 2023; 182:106262. [PMID: 37474079 DOI: 10.1016/j.micpath.2023.106262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/05/2023] [Accepted: 07/17/2023] [Indexed: 07/22/2023]
Abstract
PURPOSE Due to its high drug resistance, Acinetobacter baumannii is a priority for new therapeutic measures like vaccines. In this study, the protectivity of a combination cocktail of Omp34 and BauA as a vaccine against A. baumannii was studied in a murine sepsis model. METHODS The antibody titers were raised to Omp34 and BauA in BALB/c mice and assessed by indirect ELISA. The immunized mice were challenged with A. baumannii ATCC 19606. The bacterial loads in the liver, spleen, and lungs were also determined. RESULTS A significant increase in survival of the immunized mice was noted. In active immunity, the survival rates in mice receiving Omp34 and BauA alone or in combination were 100%. A significant decrease in the bacterial load was observed in the spleens, livers, and lungs of vaccinated mice. Anti-BauA and anti-Omp34 sera crossly detected Omp34 and BauA respectively. The decrease in bacterial load in body organs of mice vaccinated with a combination of the two proteins was significantly higher than those of the single proteins in both actively and passively immunized mice. In passive immunity, the survival rate of mice receiving specific sera raised to the combination of these proteins was 85.7%. CONCLUSION Higher protection by a combination of Omp34 and BauA than Omp34 or BauA could be attributed to targeting simultaneously both surface antigens indicating the synergistic effect of Omp34 and BauA as suitable vaccine candidates in the prevention or treatment of A. baumannii infections.
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Affiliation(s)
| | - Abolfazl Jahangiri
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mohammadreza Jalali Nadoushan
- Department of Pathology, School of Medicine, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center and Department of Biology, Shahed University, Tehran, Iran.
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Artuso I, Poddar H, Evans BA, Visca P. Genomics of Acinetobacter baumannii iron uptake. Microb Genom 2023; 9:mgen001080. [PMID: 37549061 PMCID: PMC10483418 DOI: 10.1099/mgen.0.001080] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 07/10/2023] [Indexed: 08/09/2023] Open
Abstract
Iron is essential for growth in most bacteria due to its redox activity and its role in essential metabolic reactions; it is a cofactor for many bacterial enzymes. The bacterium Acinetobacter baumannii is a multidrug-resistant nosocomial pathogen. A. baumannii responds to low iron availability imposed by the host through the exploitation of multiple iron-acquisition strategies, which are likely to deliver iron to the cell under a variety of environmental conditions, including human and animal infection. To date, six different gene clusters for active iron uptake have been described in A. baumannii , encoding protein systems involved in (i) ferrous iron uptake (feo ); (ii) haem uptake (hemT and hemO ); and (iii) synthesis and transport of the baumannoferrin(s) (bfn ), acinetobactin (bas /bau ) and fimsbactin(s) (fbs ) siderophores. Here we describe the structure, distribution and phylogeny of iron-uptake gene clusters among >1000 genotypically diverse A. baumannii isolates, showing that feo , hemT , bfn and bas /bau clusters are very prevalent across the dataset, whereas the additional haem-uptake system hemO is only present in a portion of the dataset and the fbs gene cluster is very rare. Since the expression of multiple iron-uptake clusters can be linked to virulence, the presence of the additional haem-uptake system hemO may have contributed to the success of some A. baumannii clones.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Harsh Poddar
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Benjamin A. Evans
- Norwich Medical School, University of East Anglia, Rosalind Franklin Road, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
- Fondazione Santa Lucia IRCCS, Via Ardeatina, 306/354, 00179 Rome, Italy
- National Biodiversity Future Centre, Palermo 90133, Italy
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13
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Schmitt BL, Leal BF, Leyser M, de Barros MP, Trentin DS, Ferreira CAS, de Oliveira SD. Increased ompW and ompA expression and higher virulence of Acinetobacter baumannii persister cells. BMC Microbiol 2023; 23:157. [PMID: 37246220 DOI: 10.1186/s12866-023-02904-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 05/19/2023] [Indexed: 05/30/2023] Open
Abstract
BACKGROUND Acinetobacter baumannii is one of the main causes of healthcare-associated infections that threaten public health, and carbapenems, such as meropenem, have been a therapeutic option for these infections. Therapeutic failure is mainly due to the antimicrobial resistance of A. baumannii, as well as the presence of persister cells. Persisters constitute a fraction of the bacterial population that present a transient phenotype capable of tolerating supra-lethal concentrations of antibiotics. Some proteins have been suggested to be involved in the onset and/or maintenance of this phenotype. Thus, we investigated the mRNA levels of the adeB (AdeABC efflux pump component), ompA, and ompW (outer membrane proteins) in A. baumannii cells before and after exposure to meropenem. RESULTS We found a significant increase (p-value < 0.05) in the expression of ompA (> 5.5-fold) and ompW (> 10.5-fold) in persisters. However, adeB did not show significantly different expression levels when comparing treated and untreated cells. Therefore, we suggest that these outer membrane proteins, especially OmpW, could be part of the mechanism of A. baumannii persisters to deal with the presence of high doses of meropenem. We also observed in the Galleria mellonella larvae model that persister cells are more virulent than regular ones, as evidenced by their LD50 values. CONCLUSIONS Taken together, these data contribute to the understanding of the phenotypic features of A. baumannii persisters and their relation to virulence, as well as highlight OmpW and OmpA as potential targets for drug development against A. baumannii persisters.
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Affiliation(s)
- Brenda Landvoigt Schmitt
- Laboratório de Imunologia e Microbiologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil
| | - Bruna Ferreira Leal
- Laboratório de Imunologia e Microbiologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil
| | - Mariana Leyser
- Laboratório de Imunologia e Microbiologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil
- Programa de Pós-Graduação em Biologia Celular e Molecular, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil
| | - Muriel Primon de Barros
- Laboratório de Bacteriologia e Modelos Experimentais Alternativos, Departamento de Ciências Básicas da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, UFCSPA, R. Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brazil
| | - Danielle Silva Trentin
- Laboratório de Bacteriologia e Modelos Experimentais Alternativos, Departamento de Ciências Básicas da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, UFCSPA, R. Sarmento Leite, 245, Porto Alegre, RS, 90050-170, Brazil
| | - Carlos Alexandre Sanchez Ferreira
- Laboratório de Imunologia e Microbiologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil.
- Programa de Pós-Graduação em Biologia Celular e Molecular, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil.
| | - Sílvia Dias de Oliveira
- Laboratório de Imunologia e Microbiologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil.
- Programa de Pós-Graduação em Biologia Celular e Molecular, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, Brazil.
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14
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Ren X, Palmer LD. Acinetobacter Metabolism in Infection and Antimicrobial Resistance. Infect Immun 2023:e0043322. [PMID: 37191522 DOI: 10.1128/iai.00433-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
Acinetobacter infections have high rates of mortality due to an increasing incidence of infections by multidrug-resistant (MDR) and extensively-drug-resistant (XDR) strains. Therefore, new therapeutic strategies for the treatment of Acinetobacter infections are urgently needed. Acinetobacter spp. are Gram-negative coccobacilli that are obligate aerobes and can utilize a wide variety of carbon sources. Acinetobacter baumannii is the main cause of Acinetobacter infections, and recent work has identified multiple strategies A. baumannii uses to acquire nutrients and replicate in the face of host nutrient restriction. Some host nutrient sources also serve antimicrobial and immunomodulatory functions. Hence, understanding Acinetobacter metabolism during infection may provide new insights into novel infection control measures. In this review, we focus on the role of metabolism during infection and in resistance to antibiotics and other antimicrobial agents and discuss the possibility that metabolism may be exploited to identify novel targets to treat Acinetobacter infections.
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Affiliation(s)
- Xiaomei Ren
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
| | - Lauren D Palmer
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
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15
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The Prevalence of Virulence Factor Genes among Carbapenem-Non-Susceptible Acinetobacter baumannii Clinical Strains and Their Usefulness as Potential Molecular Biomarkers of Infection. Diagnostics (Basel) 2023; 13:diagnostics13061036. [PMID: 36980344 PMCID: PMC10047099 DOI: 10.3390/diagnostics13061036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/25/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023] Open
Abstract
Healthcare-associated infections caused by multidrug-resistant Acinetobacter baumannii strains are a serious global threat. Therefore, it is important to expand the knowledge on the mechanisms of pathogenicity of these particular bacteria. The aim of this study was to assess the distribution of selected virulence factor genes (bap, surA1, omp33-36, bauA, bauS, and pld) among carbapenem-non-susceptible clinical A. baumannii isolates and to evaluate their potential usefulness as genetic markers for rapid diagnostics of A. baumannii infections. Moreover, we aimed to compare the virulence genes prevalence with the occurrence of carbapenemases genes. A total of 100 carbapenem-non-susceptible A. baumannii clinical isolates were included in the study. The presence of virulence factors and blaOXA genes was evaluated by real-time PCR. The occurrence of virulence factors genes was as follows: 100.0% for the bap and surA1 genes, 99.0% for the basD and pld genes. The bauA and omp33-36 genes were absent among the studied strains. The predominant genes (bap and surA1) are involved in biofilm formation and their presence among all clinical strains can be applied as a genetic marker to recognize A. baumannii infection. High frequencies of the basD gene—involved in siderophore biosynthesis and the gene encoding phospholipase D (pld)—were also noted among blaOXA-positive strains, showing their potential role in a pathogenicity of blaOXA-positive A. baumannii clinical strains.
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16
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Yang N, Jin X, Zhu C, Gao F, Weng Z, Du X, Feng G. Subunit vaccines for Acinetobacter baumannii. Front Immunol 2023; 13:1088130. [PMID: 36713441 PMCID: PMC9878323 DOI: 10.3389/fimmu.2022.1088130] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/22/2022] [Indexed: 01/15/2023] Open
Abstract
Acinetobacter baumannii is a gram-negative bacterium and a crucial opportunistic pathogen in hospitals. A. baumannii infection has become a challenging problem in clinical practice due to the increasing number of multidrug-resistant strains and their prevalence worldwide. Vaccines are effective tools to prevent and control A. baumannii infection. Many researchers are studying subunit vaccines against A. baumannii. Subunit vaccines have the advantages of high purity, safety, and stability, ease of production, and highly targeted induced immune responses. To date, no A. baumannii subunit vaccine candidate has entered clinical trials. This may be related to the easy degradation of subunit vaccines in vivo and weak immunogenicity. Using adjuvants or delivery vehicles to prepare subunit vaccines can slow down degradation and improve immunogenicity. The common immunization routes include intramuscular injection, subcutaneous injection, intraperitoneal injection and mucosal vaccination. The appropriate immunization method can also enhance the immune effect of subunit vaccines. Therefore, selecting an appropriate adjuvant and immunization method is essential for subunit vaccine research. This review summarizes the past exploration of A. baumannii subunit vaccines, hoping to guide current and future research on these vaccines.
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Affiliation(s)
- Ning Yang
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiao Jin
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Chenghua Zhu
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Fenglin Gao
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zheqi Weng
- The Second Clinical Medical School of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xingran Du
- Department of Infectious Disease, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China,*Correspondence: Xingran Du, ; Ganzhu Feng,
| | - Ganzhu Feng
- Department of Respiratory and Critical Care Medicine, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China,*Correspondence: Xingran Du, ; Ganzhu Feng,
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17
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Mohamad F, Alzahrani RR, Alsaadi A, Alrfaei BM, Yassin AEB, Alkhulaifi MM, Halwani M. An Explorative Review on Advanced Approaches to Overcome Bacterial Resistance by Curbing Bacterial Biofilm Formation. Infect Drug Resist 2023; 16:19-49. [PMID: 36636380 PMCID: PMC9830422 DOI: 10.2147/idr.s380883] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 12/06/2022] [Indexed: 01/05/2023] Open
Abstract
The continuous emergence of multidrug-resistant pathogens evoked the development of innovative approaches targeting virulence factors unique to their pathogenic cascade. These approaches aimed to explore anti-virulence or anti-infective therapies. There are evident concerns regarding the bacterial ability to create a superstructure, the biofilm. Biofilm formation is a crucial virulence factor causing difficult-to-treat, localized, and systemic infections. The microenvironments of bacterial biofilm reduce the efficacy of antibiotics and evade the host's immunity. Producing a biofilm is not limited to a specific group of bacteria; however, Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus biofilms are exemplary models. This review discusses biofilm formation as a virulence factor and the link to antimicrobial resistance. In addition, it explores insights into innovative multi-targeted approaches and their physiological mechanisms to combat biofilms, including natural compounds, phages, antimicrobial photodynamic therapy (aPDT), CRISPR-Cas gene editing, and nano-mediated techniques.
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Affiliation(s)
- F Mohamad
- Infectious Diseases Research Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Raghad R Alzahrani
- Nanomedicine Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia,Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Ahlam Alsaadi
- Infectious Diseases Research Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Bahauddeen M Alrfaei
- Stem Cells and Regenerative Medicine, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - Alaa Eldeen B Yassin
- College of Pharmacy, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Center, Riyadh, Saudi Arabia
| | - Manal M Alkhulaifi
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia,Manal M Alkhulaifi, P.O. Box 55670, Riyadh, 11544, Tel +966 (11) 805-1685, Email
| | - Majed Halwani
- Nanomedicine Department, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia,Correspondence: Majed Halwani, P.O. Box 3660, Mail Code 1515 (KAIMRC), Riyadh, 11481, Tel +966 (11) 429-4433, Fax +966 (11) 429-4440, Email ;
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18
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Guevara MA, Francis JD, Lu J, Manning SD, Doster RS, Moore RE, Gaddy JA. Streptococcus agalactiae cadD Is Critical for Pathogenesis in the Invertebrate Galleria mellonella Model. ACS Infect Dis 2022; 8:2405-2412. [PMID: 36445344 PMCID: PMC10262471 DOI: 10.1021/acsinfecdis.2c00453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Group B Streptococcus (GBS) is a gram-positive bacterium that can cause invasive infections in immunocompromised, elderly, pregnant, or neonatal patients. The invertebrate model, Galleria mellonella, has emerged as an effective tool to study GBS-host interactions; specifically, those conserved within the innate arm of the immune system. We sought to determine the role of metal homeostasis functions in GBS infections of G. mellonella larvae and to validate this model as a tool to study GBS-host interactions. Our results indicate that wild-type GBS infects G. mellonella in a dose-dependent manner, replicates in the invertebrate host, induces larval melanization and larval killing. These results were significantly abrogated in cohorts of larvae infected with the isogenic cadD deletion mutant. Additionally, complementation restored GBS-dependent infection, bacterial burden, larval melanization, and killing to wild-type levels. Together, these results indicate that the G. mellonella model is a useful tool for studying GBS pathogenesis.
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Affiliation(s)
- Miriam A. Guevara
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, U.S.A
| | - Jamisha D. Francis
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, U.S.A
| | - Jacky Lu
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, U.S.A
| | - Shannon D. Manning
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48864, U.S.A
| | - Ryan S. Doster
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232, U.S.A
| | - Rebecca E. Moore
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, U.S.A
| | - Jennifer A. Gaddy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, 37232, U.S.A
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232, U.S.A
- Tennessee Valley Healthcare Systems, Department of Veterans Affairs, Nashville, Tennessee, 37212, U.S.A
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19
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Tang M, Ding G, Lu X, Huang Q, Du H, Xiao G, Wang D. Exposure to Nanoplastic Particles Enhances Acinetobacter Survival, Biofilm Formation, and Serum Resistance. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12234222. [PMID: 36500844 PMCID: PMC9735686 DOI: 10.3390/nano12234222] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/10/2022] [Accepted: 11/25/2022] [Indexed: 05/04/2023]
Abstract
The interaction between nanoplastics and bacteria remains still largely unclear. In this study, we determined the effect of nanopolystyrene particle (NP) on a bacterial pathogen of Acinetobacter johnsonii AC15. Scanning electron microscopy (SEM) analysis indicated the aggregation of NPs from 10 μg/L to 100 μg/L on surface of A. johnsonii AC15, suggesting that A. johnsonii AC15 acted as the vector for NPs. Exposure to 100−1000 μg/L NPs increased the growth and colony-forming unit (CFU) of A. johnsonii AC15. In addition, exposure to 100−1000 μg/L NPs enhanced the amount of formed biofilm of A. johnsonii AC15. Alterations in expressions of 3 survival-related (zigA, basD, and zur), 5 biofilm formation-related (ompA, bap, adeG, csuC, and csuD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were observed after exposure to 1000 μg/L NPs. Moreover, both CFU and survival rate of A. johnsonii AC15 in normal human serum (NHS) were significantly increased by 1−1000 μg/L NPs, suggesting the enhancement in serum resistance of Acinetobacter pathogen by NPs. In the NHS, expressions of 3 survival-related (zigA, basD, and zur), 9 biofilm formation-related (ompA, bap, adeF, adeG, csuA/B, csuC, csuD, csuE, and hlyD), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were affected by 1000 μg/L NPs. Expressions of 1 survival-related (zigA), 5 biofilm formation-related (bap, adeG, csuC, csuD, and csuE), and 3 serum resistance-related virulence genes (lpxC, lpxL, and pbpG) were also altered by 10 μg/L NPs after the addition of NHS. Therefore, exposure to NPs in the range of μg/L has the potential to enhance bacterial virulence by increasing their growth, biofilm formation, and serum resistance.
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Affiliation(s)
- Mingfeng Tang
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
| | - Guoying Ding
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
| | - Xiaoyu Lu
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
| | - Qian Huang
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
| | - Huihui Du
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
| | - Guosheng Xiao
- College of Biology and Food Engineering, Chongqing Three Gorges University, Wanzhou 404100, China
- Correspondence: (G.X.); (D.W.)
| | - Dayong Wang
- Medical School, Southeast University, Nanjing 210009, China
- Correspondence: (G.X.); (D.W.)
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20
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Iron Acquisition Mechanisms and Their Role in the Virulence of Acinetobacter baumannii. Infect Immun 2022; 90:e0022322. [PMID: 36066263 PMCID: PMC9584212 DOI: 10.1128/iai.00223-22] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Iron is an essential element for survival of most organisms. One mechanism of host defense is to tightly chelate iron to several proteins to limit its extracellular availability. This has forced pathogens such as Acinetobacter baumannii to adapt mechanisms for the acquisition and utilization of iron even in iron-limiting conditions. A. baumannii uses a variety of iron acquisition strategies to meet its iron requirements. It can lyse erythrocytes to harvest the heme molecules, use iron-chelating siderophores, and use outer membrane vesicles to acquire iron. Iron acquisition pathways, in general, have been seen to affect many other virulence factors such as cell adherence, cell motility, and biofilm formation. The knowledge gained from research on iron acquisition led to the synthesis of the antibiotic cefiderocol, which uses iron uptake pathways for entry into the cell with some success as a novel cephalosporin. Understanding the mechanisms of iron acquisition of A. baumannii allows for insight into clinical infections and offer potential targets for novel antibiotics or potentiators of current drugs.
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21
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Zhou J, Ventura CJ, Yu Y, Gao W, Fang RH, Zhang L. Biomimetic Neutrophil Nanotoxoids Elicit Potent Immunity against Acinetobacter baumannii in Multiple Models of Infection. NANO LETTERS 2022; 22:7057-7065. [PMID: 35998891 PMCID: PMC9971251 DOI: 10.1021/acs.nanolett.2c01948] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Acinetobacter baumannii is a leading cause of antibiotic-resistant nosocomial infections with high mortality rates, yet there is currently no clinically approved vaccine formulation. During the onset of A. baumannii infection, neutrophils are the primary responders and play a major role in resisting the pathogen. Here, we design a biomimetic nanotoxoid for antivirulence vaccination by using neutrophil membrane-coated nanoparticles to safely capture secreted A. baumannii factors. Vaccination with the nanotoxoid formulation rapidly mobilizes innate immune cells and promotes pathogen-specific adaptive immunity. In murine models of pneumonia, septicemia, and superficial wound infection, immunization with the nanovaccine offers significant protection, improving survival and reducing signs of acute inflammation. Lower bacterial burdens are observed in vaccinated animals regardless of the infection route. Altogether, neutrophil nanotoxoids represent an effective platform for eliciting multivalent immunity to protect against multidrug-resistant A. baumannii in a wide range of disease conditions.
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Affiliation(s)
- Jiarong Zhou
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Christian J. Ventura
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Yiyan Yu
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Weiwei Gao
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Ronnie H. Fang
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Liangfang Zhang
- Department of NanoEngineering, Chemical Engineering Program, and Moores Cancer Center, University of California San Diego, La Jolla, CA 92093, U.S.A
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Sheldon JR, Himmel LE, Kunkle DE, Monteith AJ, Maloney KN, Skaar EP. Lipocalin-2 is an essential component of the innate immune response to Acinetobacter baumannii infection. PLoS Pathog 2022; 18:e1010809. [PMID: 36054235 PMCID: PMC9477428 DOI: 10.1371/journal.ppat.1010809] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/15/2022] [Accepted: 08/12/2022] [Indexed: 12/11/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen and an emerging global health threat. Within healthcare settings, major presentations of A. baumannii include bloodstream infections and ventilator-associated pneumonia. The increased prevalence of ventilated patients during the COVID-19 pandemic has led to a rise in secondary bacterial pneumonia caused by multidrug resistant (MDR) A. baumannii. Additionally, due to its MDR status and the lack of antimicrobial drugs in the development pipeline, the World Health Organization has designated carbapenem-resistant A. baumannii to be its priority critical pathogen for the development of novel therapeutics. To better inform the design of new treatment options, a comprehensive understanding of how the host contains A. baumannii infection is required. Here, we investigate the innate immune response to A. baumannii by assessing the impact of infection on host gene expression using NanoString technology. The transcriptional profile observed in the A. baumannii infected host is characteristic of Gram-negative bacteremia and reveals expression patterns consistent with the induction of nutritional immunity, a process by which the host exploits the availability of essential nutrient metals to curtail bacterial proliferation. The gene encoding for lipocalin-2 (Lcn2), a siderophore sequestering protein, was the most highly upregulated during A. baumannii bacteremia, of the targets assessed, and corresponds to robust LCN2 expression in tissues. Lcn2-/- mice exhibited distinct organ-specific gene expression changes including increased transcription of genes involved in metal sequestration, such as S100A8 and S100A9, suggesting a potential compensatory mechanism to perturbed metal homeostasis. In vitro, LCN2 inhibits the iron-dependent growth of A. baumannii and induces iron-regulated gene expression. To elucidate the role of LCN2 in infection, WT and Lcn2-/- mice were infected with A. baumannii using both bacteremia and pneumonia models. LCN2 was not required to control bacterial growth during bacteremia but was protective against mortality. In contrast, during pneumonia Lcn2-/- mice had increased bacterial burdens in all organs evaluated, suggesting that LCN2 plays an important role in inhibiting the survival and dissemination of A. baumannii. The control of A. baumannii infection by LCN2 is likely multifactorial, and our results suggest that impairment of iron acquisition by the pathogen is a contributing factor. Modulation of LCN2 expression or modifying the structure of LCN2 to expand upon its ability to sequester siderophores may thus represent feasible avenues for therapeutic development against this pathogen. A lack of therapeutic options has prompted the World Health Organization to designate multidrug-resistant Acinetobacter baumannii as its priority critical pathogen for research into new treatment strategies. The mechanisms employed by A. baumannii to cause disease and the host tactics exercised to constrain infection are not fully understood. Here, we further characterize the innate immune response to A. baumannii infection. We identify nutritional immunity, a process where the availability of nutrient metals is exploited to restrain bacterial growth, as being induced during infection. The gene encoding for lipocalin-2 (Lcn2), a protein that can impede iron uptake by bacteria, is highly upregulated in infected mice, and corresponds to robust LCN2 detection in the tissues. We find that LCN2 is crucial to reducing mortality from A. baumannii bacteremia and inhibits dissemination of the pathogen during pneumonia. In wild-type and Lcn2-deficient mice, broader transcriptional profiling reveals expression patterns consistent with the known response to Gram-negative bacteremia. Although the role of LCN2 in infection is likely multifactorial, we find its antimicrobial effects are at least partly exerted by impairing iron acquisition by A. baumannii. Facets of nutritional immunity, such as LCN2, may be exploited as novel therapeutics in combating A. baumannii infection.
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Affiliation(s)
- Jessica R. Sheldon
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Lauren E. Himmel
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Dillon E. Kunkle
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Andrew J. Monteith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - K. Nichole Maloney
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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Chaudhuri S, Rasooli I, Oskouei RH, Pishgahi M, Jahangir A, Andisi VF, Schryvers AB. Hybrid antigens expressing surface loops of BauA from Acinetobacter baumannii are capable of inducing protection against infection. Front Immunol 2022; 13:933445. [PMID: 36045685 PMCID: PMC9420935 DOI: 10.3389/fimmu.2022.933445] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is a human bacterial pathogen of increasing concern in clinical settings due to the emergence of antibiotic resistant strains and the lack of effective therapeutics. Researchers have been exploring new treatment options such as novel drug candidates and vaccines to prevent severe infections and mortality. Bacterial surface antigens that are essential to A. baumannii for acquiring micronutrients (e.g. iron, zinc) from nutrient restricted environments are being considered as targets for vaccines or immunotherapy due to their crucial role for growth and pathogenesis in the human host. BauA, the outer membrane receptor for the siderophore acinetobactin was targeted for vaccine development in this study. Due to challenges in the commercial production of membrane proteins for vaccines, a novel hybrid antigen method developed by our group was used. Exposed loops of BauA were selected and displayed on a foreign scaffold to generate novel hybrid antigens designed to elicit an immune response against the native BauA protein. The potential epitopes were incorporated into a scaffold derived from the C-lobe of Neisseria meningitidis transferrin binding protein B (TbpB), named the loopless C-lobe (LCL). Hybrid proteins displaying three selected loops (5, 7 and 8) individually or in combination were designed and produced and evaluated in an A. baumannii murine sepsis model as vaccine antigens. Immunization with the recombinant BauA protein protected 100% of the mice while immunization with hybrid antigens displaying individual loops achieved between 50 and 100% protection. The LCL scaffold did not induce a protective immune response, enabling us to attribute the observed protection elicited by the hybrid antigens to the displayed loops. Notably, the mice immunized with the hybrid antigen displaying loop 7 were completely protected from infection. Taken together, these results suggest that our hybrid antigen approach is a viable method for generating novel vaccine antigens that target membrane surface proteins necessary for bacterial growth and pathogenesis and the loop 7 hybrid antigen can be a foundation for approaches to combat A. baumannii infections.
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Affiliation(s)
- Somshukla Chaudhuri
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran
| | | | | | - Abolfazl Jahangir
- Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Vahid Farshchi Andisi
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Anthony B. Schryvers
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- *Correspondence: Anthony B. Schryvers,
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24
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BauA and Omp34 surface loops trigger protective antibodies against Acinetobacter baumannii in a murine sepsis model. Int Immunopharmacol 2022; 108:108731. [DOI: 10.1016/j.intimp.2022.108731] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/16/2022] [Accepted: 03/22/2022] [Indexed: 12/13/2022]
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25
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Gairola A, Benjamin A, Weatherston JD, Cirillo JD, Wu HJ. Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages. ADVANCED THERAPEUTICS 2022; 5:2100193. [PMID: 36203881 PMCID: PMC9531895 DOI: 10.1002/adtp.202100193] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Indexed: 11/10/2022]
Abstract
Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.
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Affiliation(s)
- Anirudh Gairola
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Aaron Benjamin
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, USA
| | - Joshua D Weatherston
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Jeffrey D Cirillo
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, USA
| | - Hung-Jen Wu
- Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
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Fernandez JS, Tuttobene MR, Montaña S, Subils T, Cantera V, Iriarte A, Tuchscherr L, Ramirez MS. Staphylococcus aureus α-Toxin Effect on Acinetobacter baumannii Behavior. BIOLOGY 2022; 11:biology11040570. [PMID: 35453769 PMCID: PMC9028598 DOI: 10.3390/biology11040570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 04/02/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022]
Abstract
Polymicrobial infections are more challenging to treat and are recognized as responsible for significant morbidity and mortality. It has been demonstrated that multiple Gram-negative organisms take advantage of the effects of Staphylococcus aureus α-toxin on mucosal host defense, resulting in proliferation and dissemination of the co-infecting pathogens. Through phenotypic approaches, we observed a decrease in the motility of A. baumannii A118 after exposure to cell-free conditioned media (CFCM) of S. aureus strains, USA300 and LS1. However, the motility of A. baumannii A118 was increased after exposure to the CFCM of S. aureus strains USA300 Δhla and S. aureus LSI ΔagrA. Hemolytic activity was seen in A118, in the presence of CFCM of S. aureus LS1. Further, A. baumannii A118 showed an increase in biofilm formation and antibiotic resistance to tetracycline, in the presence of CFCM of S. aureus USA300. Transcriptomic analysis of A. baumannii A118, with the addition of CFCM from S. aureus USA300, was carried out to study A. baumannii response to S. aureus’ released molecules. The RNA-seq data analysis showed a total of 463 differentially expressed genes, associated with a wide variety of functions, such as biofilm formation, virulence, and antibiotic susceptibility, among others. The present results showed that A. baumannii can sense and respond to molecules secreted by S. aureus. These findings demonstrate that A. baumannii may perceive and respond to changes in its environment; specifically, when in the presence of CFCM from S. aureus.
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Affiliation(s)
- Jennifer S. Fernandez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (J.S.F.); (M.R.T.)
| | - Marisel R. Tuttobene
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (J.S.F.); (M.R.T.)
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Rosario S2000, Argentina
| | - Sabrina Montaña
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Buenos Aires C1113, Argentina;
| | - Tomás Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2000, Argentina;
| | - Virginia Cantera
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Facultad de Medicina, Universidad de la República, Montevideo 11200, Uruguay; (V.C.); (A.I.)
| | - Andrés Iriarte
- Laboratorio de Biología Computacional, Departamento de Desarrollo Biotecnológico, Facultad de Medicina, Universidad de la República, Montevideo 11200, Uruguay; (V.C.); (A.I.)
| | - Lorena Tuchscherr
- Institute of Medical Microbiology, Jena University Hospital, 07747 Jena, Germany;
| | - Maria Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA 92831, USA; (J.S.F.); (M.R.T.)
- Correspondence: ; Tel.: +1-657-278-4562
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Kho ZY, Azad MAK, Han ML, Zhu Y, Huang C, Schittenhelm RB, Naderer T, Velkov T, Selkrig J, Zhou Q(T, Li J. Correlative proteomics identify the key roles of stress tolerance strategies in Acinetobacter baumannii in response to polymyxin and human macrophages. PLoS Pathog 2022; 18:e1010308. [PMID: 35231068 PMCID: PMC8887720 DOI: 10.1371/journal.ppat.1010308] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/26/2022] [Indexed: 11/19/2022] Open
Abstract
The opportunistic pathogen Acinetobacter baumannii possesses stress tolerance strategies against host innate immunity and antibiotic killing. However, how the host-pathogen-antibiotic interaction affects the overall molecular regulation of bacterial pathogenesis and host response remains unexplored. Here, we simultaneously investigate proteomic changes in A. baumannii and macrophages following infection in the absence or presence of the polymyxins. We discover that macrophages and polymyxins exhibit complementary effects to disarm several stress tolerance and survival strategies in A. baumannii, including oxidative stress resistance, copper tolerance, bacterial iron acquisition and stringent response regulation systems. Using the spoT mutant strains, we demonstrate that bacterial cells with defects in stringent response exhibit enhanced susceptibility to polymyxin killing and reduced survival in infected mice, compared to the wild-type strain. Together, our findings highlight that better understanding of host-pathogen-antibiotic interplay is critical for optimization of antibiotic use in patients and the discovery of new antimicrobial strategy to tackle multidrug-resistant bacterial infections.
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Affiliation(s)
- Zhi Ying Kho
- Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Mohammad A. K. Azad
- Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Mei-Ling Han
- Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Yan Zhu
- Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Cheng Huang
- Monash Proteomics & Metabolomics Facility, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Ralf B. Schittenhelm
- Monash Proteomics & Metabolomics Facility, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Thomas Naderer
- Biomedicine Discovery Institute, Infection Program, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Joel Selkrig
- European Molecular Biology Laboratory, Genome Biology Unit, Heidelberg, Germany
| | - Qi (Tony) Zhou
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, Indiana, United States of America
| | - Jian Li
- Biomedicine Discovery Institute, Infection Program and Department of Microbiology, Monash University, Clayton, Victoria, Australia
- * E-mail:
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Abstract
The spread of antibiotic-resistant Acinetobacter baumannii poses a significant threat to public health worldwide. This nosocomial bacterial pathogen can be associated with life-threatening infections, particularly in intensive care units. A. baumannii is mainly described as an extracellular pathogen with restricted survival within cells. This study shows that a subset of A. baumannii clinical isolates extensively multiply within nonphagocytic immortalized and primary cells without the induction of apoptosis and with bacterial clusters visible up to 48 h after infection. This phenotype was observed for the A. baumannii C4 strain associated with high mortality in a hospital outbreak and the A. baumannii ABC141 strain, which was isolated from the skin but was found to be hyperinvasive. Intracellular multiplication of these A. baumannii strains occurred within spacious single membrane-bound vacuoles, labeled with the lysosomal associate membrane protein (LAMP1). However, these compartments excluded lysotracker, an indicator of acidic pH, suggesting that A. baumannii can divert its trafficking away from the lysosomal degradative pathway. These compartments were also devoid of autophagy features. A high-content microscopy screen of 43 additional A. baumannii clinical isolates highlighted various phenotypes, and (i) the majority of isolates remained extracellular, (ii) a significant proportion was capable of invasion and limited persistence, and (iii) three more isolates efficiently multiplied within LAMP1-positive vacuoles, one of which was also hyperinvasive. These data identify an intracellular niche for specific A. baumannii clinical isolates that enables extensive multiplication in an environment protected from host immune responses and out of reach of many antibiotics. IMPORTANCE Multidrug-resistant Acinetobacter baumannii isolates are associated with significant morbidity and mortality in hospitals worldwide. Understanding their pathogenicity is critical for improving therapeutic management. Although A. baumannii can steadily adhere to surfaces and host cells, most bacteria remain extracellular. Recent studies have shown that a small proportion of bacteria can invade cells but present limited survival. We have found that some A. baumannii clinical isolates can establish a specialized intracellular niche that sustains extensive intracellular multiplication for a prolonged time without induction of cell death. We propose that this intracellular compartment allows A. baumannii to escape the cell’s normal degradative pathway, protecting bacteria from host immune responses and potentially hindering antibiotic accessibility. This may contribute to A. baumannii persistence, relapsing infections, and enhanced mortality in susceptible patients. A high-content microscopy-based screen confirmed that this pathogenicity trait is present in other clinical A. baumannii isolates. There is an urgent need for new antibiotics or alternative antimicrobial approaches, particularly to combat carbapenem-resistant A. baumannii. The discovery of an intracellular niche for this pathogen, as well as hyperinvasive isolates, may help guide the development of antimicrobial therapies and diagnostics in the future.
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29
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Artuso I, Lucidi M, Visaggio D, Capecchi G, Lugli GA, Ventura M, Visca P. Genome diversity of domesticated Acinetobacter baumannii ATCC 19606 T strains. Microb Genom 2022; 8. [PMID: 35084299 PMCID: PMC8914354 DOI: 10.1099/mgen.0.000749] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii has emerged as an important opportunistic pathogen worldwide, being responsible for large outbreaks for nosocomial infections, primarily in intensive care units. A. baumannii ATCC 19606T is the species type strain, and a reference organism in many laboratories due to its low virulence, amenability to genetic manipulation and extensive antibiotic susceptibility. We wondered if frequent propagation of A. baumannii ATCC 19606T in different laboratories may have driven micro- and macro-evolutionary events that could determine inter-laboratory differences of genome-based data. By combining Illumina MiSeq, MinION and Sanger technologies, we generated a high-quality whole-genome sequence of A. baumannii ATCC 19606T, then performed a comparative genome analysis between A. baumannii ATCC 19606T strains from several research laboratories and a reference collection. Differences between publicly available ATCC 19606T genome sequences were observed, including SNPs, macro- and micro-deletions, and the uneven presence of a 52 kb prophage belonging to genus Vieuvirus. Two plasmids, pMAC and p1ATCC19606, were invariably detected in all tested strains. The presence of a putative replicase, a replication origin containing four 22-mer direct repeats, and a toxin-antitoxin system implicated in plasmid stability were predicted by in silico analysis of p1ATCC19606, and experimentally confirmed. This work refines the sequence, structure and functional annotation of the A. baumannii ATCC 19606T genome, and highlights some remarkable differences between domesticated strains, likely resulting from genetic drift.
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Affiliation(s)
- Irene Artuso
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Massimiliano Lucidi
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Daniela Visaggio
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy.,Santa Lucia Fundation IRCCS, Via Ardeatina 306-354, 00179 Rome, Italy
| | - Giulia Capecchi
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy
| | - Gabriele Andrea Lugli
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Marco Ventura
- Laboratory of Probiogenomics, Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11a, 43124 Parma, Italy
| | - Paolo Visca
- Department of Science, Roma Tre University, Viale G. Marconi 446, 00146 Rome, Italy.,Santa Lucia Fundation IRCCS, Via Ardeatina 306-354, 00179 Rome, Italy
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Abstract
Infection by multidrug-resistant (MDR) Acinetobacter baumannii is one of the major causes of hospital-acquired infections worldwide. The ability of A. baumannii to survive in adverse conditions as well as its extensive antimicrobial resistance make it one of the most difficult to treat pathogens associated with high mortality rates. The aim of this study was to investigate MDR A. baumannii that has spread among pediatric cancer patients in the Children’s Cancer Hospital Egypt 57357. Whole-genome sequencing was used to characterize 31 MDR A. baumannii clinical isolates. Phenotypically, the isolates were MDR, with four isolates showing resistance to the last-resort antibiotic colistin. Multilocus sequence typing showed the presence of eight clonal groups, two of which were previously reported to cause outbreaks in Egypt, and one novel sequence type (ST), Oxf-ST2246. Identification of the circulating plasmids showed the presence of two plasmid lineages in the isolates, strongly governed by sequence type. A large number of antimicrobial genes with a range of resistance mechanisms were detected in the isolates, including β-lactamases and antibiotic efflux pumps. Analysis of insertion sequences (ISs) revealed the presence of ISAba1 and ISAba125 in all the samples, which amplify β-lactamase expression, causing extensive carbapenem resistance. Mutation analysis was used to decipher underlying mutations responsible for colistin resistance and revealed novel mutations in several outer membrane proteins, in addition to previously reported mutations in pmrB. Altogether, understanding the transmissibility of A. baumannii as well as its resistance and virulence mechanisms will help develop novel treatment options for better management of hospital-acquired infections. IMPORTANCEAcinetobacter baumannii represents a major health threat, in particular among immunocompromised cancer patients. The rise in carbapenem-resistant A. baumannii, and the development of resistance to the last-resort antimicrobial agent colistin, complicates the management of A. baumannii outbreaks and increases mortality rates. Here, we investigate 31 multidrug resistant A. baumannii isolates from pediatric cancer patients in Children’s Cancer Hospital Egypt (CCHE) 57357 via whole-genome sequencing. Multilocus sequence typing (MLST) showed the presence of eight clonal groups including a novel sequence type. In silico detection of antimicrobial-resistant genes and virulence factors revealed a strong correlation between certain virulence genes and mortality as well as several point mutations in outer membrane proteins contributing to colistin resistance. Detection of CRISPR/Cas sequences in the majority of the samples was strongly correlated with the presence of prophage sequences and associated with failure of bacteriophage therapy. Altogether, understanding the genetic makeup of circulating A. baumannii is essential for better management of outbreaks.
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31
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Acinetobacter baumannii regulates its stress responses via the BfmRS two-component regulatory system. J Bacteriol 2021; 204:e0049421. [PMID: 34871031 DOI: 10.1128/jb.00494-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a common nosocomial pathogen that utilizes numerous mechanisms to aid its survival in both the environment and in the host. Coordination of such mechanisms requires an intricate regulatory network. We report here that A. baumannii can directly regulate several stress-related pathways via the two-component regulatory system, BfmRS. Similar to previous studies, results from transcriptomic analysis showed that mutation of the BfmR response regulator causes dysregulation of genes required for the oxidative stress response, the osmotic stress response, the misfolded protein/heat shock response, Csu pili/fimbriae production, and capsular polysaccharide biosynthesis. We also found that the BfmRS system is involved in controlling siderophore biosynthesis and transport, and type IV pili production. We provide evidence that BfmR binds to various stress-related promoter regions and show that BfmR alone can directly activate transcription of some stress-related genes. Additionally, we show that the BfmS sensor kinase acts as a BfmR phosphatase to negatively regulate BfmR activity. This work highlights the importance of the BfmRS system in promoting survival of A. baumannii. Importance Acinetobacter baumannii is a nosocomial pathogen that has extremely high rates of multidrug resistance. This organism's ability to endure stressful conditions is a key part of its ability to spread in the hospital environment and cause infections. Unlike other members of the γ-proteobacteria, A. baumannii does not encode a homolog of the RpoS sigma factor to coordinate its stress response. Here, we demonstrate that the BfmRS two-component system directly controls the expression of multiple stress resistance genes. Our findings suggest that BfmRS is central to a unique scheme of general stress response regulation by A. baumannii.
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Tao Y, Duma L, Rossez Y. Galleria mellonella as a Good Model to Study Acinetobacter baumannii Pathogenesis. Pathogens 2021; 10:1483. [PMID: 34832638 PMCID: PMC8623143 DOI: 10.3390/pathogens10111483] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/08/2021] [Accepted: 11/10/2021] [Indexed: 12/29/2022] Open
Abstract
The invertebrate model, Galleria mellonella, has been widely used to study host-pathogen interactions due to its cheapness, ease of handling, and similar mammalian innate immune system. G. mellonella larvae have been proven to be useful and a reliable model for analyzing pathogenesis mechanisms of multidrug resistant Acinetobacter baumannii, an opportunistic pathogen difficult to kill. This review describes the detailed experimental design of G. mellonella/A. baumannii models, and provides a comprehensive comparison of various virulence factors and therapy strategies using the G. mellonella host. These investigations highlight the importance of this host-pathogen model for in vivo pathogen virulence studies. On the long term, further development of the G. mellonella/A. baumannii model will offer promising insights for clinical treatments of A. baumannii infection.
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Affiliation(s)
- Ye Tao
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de Recherche Royallieu–CS 60 319 , 60203 Compiègne, France; (Y.T.); (L.D.)
| | - Luminita Duma
- Université de Technologie de Compiègne, UPJV, UMR CNRS 7025, Enzyme and Cell Engineering, Centre de Recherche Royallieu–CS 60 319 , 60203 Compiègne, France; (Y.T.); (L.D.)
- Université de Reims Champagne-Ardenne, CNRS, ICMR UMR 7312, 51097 Reims, France
| | - Yannick Rossez
- Université Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
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Bateman TJ, Shah M, Ho TP, Shin HE, Pan C, Harris G, Fegan JE, Islam EA, Ahn SK, Hooda Y, Gray-Owen SD, Chen W, Moraes TF. A Slam-dependent hemophore contributes to heme acquisition in the bacterial pathogen Acinetobacter baumannii. Nat Commun 2021; 12:6270. [PMID: 34725337 PMCID: PMC8560813 DOI: 10.1038/s41467-021-26545-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 10/06/2021] [Indexed: 12/02/2022] Open
Abstract
Nutrient acquisition systems are often crucial for pathogen growth and survival during infection, and represent attractive therapeutic targets. Here, we study the protein machinery required for heme uptake in the opportunistic pathogen Acinetobacter baumannii. We show that the hemO locus, which includes a gene encoding the heme-degrading enzyme, is required for high-affinity heme acquisition from hemoglobin and serum albumin. The hemO locus includes a gene coding for a heme scavenger (HphA), which is secreted by a Slam protein. Furthermore, heme uptake is dependent on a TonB-dependent receptor (HphR), which is important for survival and/or dissemination into the vasculature in a mouse model of pulmonary infection. Our results indicate that A. baumannii uses a two-component receptor system for the acquisition of heme from host heme reservoirs.
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Affiliation(s)
- Thomas J Bateman
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Megha Shah
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Timothy Pham Ho
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | | | - Chuxi Pan
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Greg Harris
- National Research Council Canada, Human Health Therapeutics (HHT) Research Center, Ottawa, ON, Canada
| | - Jamie E Fegan
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Epshita A Islam
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Sang Kyun Ahn
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Yogesh Hooda
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Scott D Gray-Owen
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Wangxue Chen
- National Research Council Canada, Human Health Therapeutics (HHT) Research Center, Ottawa, ON, Canada
| | - Trevor F Moraes
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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Islam MM, Kim K, Lee JC, Shin M. LeuO, a LysR-Type Transcriptional Regulator, Is Involved in Biofilm Formation and Virulence of Acinetobacter baumannii. Front Cell Infect Microbiol 2021; 11:738706. [PMID: 34708004 PMCID: PMC8543017 DOI: 10.3389/fcimb.2021.738706] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/23/2021] [Indexed: 12/05/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen that can survive in different environmental conditions and poses a severe threat to public health due to its multidrug resistance properties. Research on transcriptional regulators, which play an essential role in adjusting to new environments, could provide new insights into A. baumannii pathogenesis. LysR-type transcriptional regulators (LTTRs) are structurally conserved among bacterial species and regulate virulence in many pathogens. We identified a novel LTTR, designated as LeuO encoded in the A. baumannii genome. After construction of LeuO mutant strain, transcriptome analysis showed that LeuO regulates the expression of 194 upregulated genes and 108 downregulated genes responsible for various functions and our qPCR validation of several differentially expressed genes support transcriptome data. Our results demonstrated that disruption of LeuO led to increased biofilm formation and increased pathogenicity in an animal model. However, the adherence and surface motility of the LeuO mutant were reduced compared with those of the wild-type strain. We observed some mutations on amino acids sequence of LeuO in clinical isolates. These mutations in the A. baumannii biofilm regulator LeuO may cause hyper-biofilm in the tested clinical isolates. This study is the first to demonstrate the association between the LTTR member LeuO and virulence traits of A. baumannii.
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Affiliation(s)
- Md Maidul Islam
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, South Korea
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35
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The Molecular Basis of Acinetobacter baumannii Cadmium Toxicity and Resistance. Appl Environ Microbiol 2021; 87:e0171821. [PMID: 34495707 DOI: 10.1128/aem.01718-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Acinetobacter species are ubiquitous Gram-negative bacteria that can be found in water, in soil, and as commensals of the human skin. The successful inhabitation of Acinetobacter species in diverse environments is primarily attributable to the expression of an arsenal of stress resistance determinants, which includes an extensive repertoire of metal ion efflux systems. Metal ion homeostasis in the hospital pathogen Acinetobacter baumannii contributes to pathogenesis; however, insights into its metal ion transporters for environmental persistence are lacking. Here, we studied the impact of cadmium stress on A. baumannii. Our functional genomics and independent mutant analyses revealed a primary role for CzcE, a member of the cation diffusion facilitator (CDF) superfamily, in resisting cadmium stress. We also show that the CzcCBA heavy metal efflux system contributes to cadmium efflux. Collectively, these systems provide A. baumannii with a comprehensive cadmium translocation pathway from the cytoplasm to the periplasm and subsequently the extracellular space. Furthermore, analysis of the A. baumannii metallome under cadmium stress showed zinc depletion, as well as copper enrichment, both of which are likely to influence cellular fitness. Overall, this work provides new knowledge on the role of a broad arsenal of membrane transporters in A. baumannii metal ion homeostasis. IMPORTANCE Cadmium toxicity is a widespread problem, yet the interaction of this heavy metal with biological systems is poorly understood. Some microbes have evolved traits to proactively counteract cadmium toxicity, including Acinetobacter baumannii, which is notorious for persisting in harsh environments. Here, we show that A. baumannii utilizes a dedicated cadmium efflux protein in concert with a system that is primarily attuned to zinc efflux to efficiently overcome cadmium stress. The molecular characterization of A. baumannii under cadmium stress revealed how active cadmium efflux plays a key role in preventing the dysregulation of bacterial metal ion homeostasis, which appeared to be a primary means by which cadmium exerts toxicity upon the bacterium.
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Kim N, Son JH, Kim K, Kim HJ, Kim YJ, Shin M, Lee JC. Global regulator DksA modulates virulence of Acinetobacter baumannii. Virulence 2021; 12:2750-2763. [PMID: 34696704 PMCID: PMC8583241 DOI: 10.1080/21505594.2021.1995253] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
DksA with (p)ppGpp regulates a wide range of gene transcriptions during the stringent response. The aim of this study was to identify a DksA ortholog in Acinetobacter baumannii and clarify the roles of DksA in bacterial physiology and virulence. The ∆dksA mutant and its complemented strains were constructed using A. baumannii ATCC 17978. The AlS_0248 in A. baumannii ATCC 17978 was identified to dksA using sequence homology, protein structure prediction, and gene expression patterns under different culture conditions. The ∆dksA mutant strain showed a filamentous morphology compared with the wild-type (WT) strain. Bacterial growth was decreased in the ∆dksA mutant strain under static conditions. Surface motility was decreased in the ∆dksA mutant strain compared with the WT strain. In contrast, biofilm formation was increased and biofilm-associated genes, such as bfmR/S and csuC/D/E, were upregulated in the ∆dksA mutant strain. The ∆dksA mutant strain produced less autoinducers than the WT strain. The expression of abaI and abaR was significantly decreased in the ∆dksA mutant strain. Furthermore, the ∆dksA mutant strain showed less bacterial burden and milder histopathological changes in the lungs of mice than the WT strain. Mice survival was also significantly different between the ∆dksA mutant and WT strains. Conclusively, DksA is directly or indirectly involved in regulating a wide range of genes associated with bacterial physiology and virulence, which contributes to the pathogenesis of A. baumannii. Thus, DksA is a potential anti-virulence target for A. baumannii infection.
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Affiliation(s)
- Nayeong Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Joo Hee Son
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hyo Jeong Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Yoo Jeong Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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37
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Conde-Pérez K, Vázquez-Ucha JC, Álvarez-Fraga L, Ageitos L, Rumbo-Feal S, Martínez-Guitián M, Trigo-Tasende N, Rodríguez J, Bou G, Jiménez C, Beceiro A, Poza M. In-Depth Analysis of the Role of the Acinetobactin Cluster in the Virulence of Acinetobacter baumannii. Front Microbiol 2021; 12:752070. [PMID: 34675911 PMCID: PMC8524058 DOI: 10.3389/fmicb.2021.752070] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
Acinetobacter baumannii is a multidrug-resistant pathogen that represents a serious threat to global health. A. baumannii possesses a wide range of virulence factors that contribute to the bacterial pathogenicity. Among them, the siderophore acinetobactin is one of the most important, being essential for the development of the infection. In this study we performed an in-depth analysis of the acinetobactin cluster in the strain A. baumannii ATCC 17978. For this purpose, nineteen individual isogenic mutant strains were generated, and further phenotypical analysis were performed. Individual mutants lacking the biosynthetic genes entA, basG, basC, basD, and basB showed a significant loss in virulence, due to the disruption in the acinetobactin production. Similarly, the gene bauA, coding for the acinetobactin receptor, was also found to be crucial for the bacterial pathogenesis. In addition, the analysis of the ΔbasJ/ΔfbsB double mutant strain demonstrated the high level of genetic redundancy between siderophores where the role of specific genes of the acinetobactin cluster can be fulfilled by their fimsbactin redundant genes. Overall, this study highlights the essential role of entA, basG, basC, basD, basB and bauA in the pathogenicity of A. baumannii and provides potential therapeutic targets for the design of new antivirulence agents against this microorganism.
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Affiliation(s)
- Kelly Conde-Pérez
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
| | - Juan C Vázquez-Ucha
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Laura Álvarez-Fraga
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD, Australia
| | - Lucía Ageitos
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Soraya Rumbo-Feal
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
| | - Marta Martínez-Guitián
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Noelia Trigo-Tasende
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Jaime Rodríguez
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Germán Bou
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Carlos Jiménez
- Centro de Investigaciones Científicas Avanzadas (CICA) y Departamento de Química, Facultad de Ciencias, Agrupación Estratégica CICA-INIBIC, Universidad de A Coruña, A Coruña, Spain
| | - Alejandro Beceiro
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain
| | - Margarita Poza
- Servicio de Microbiología del Complejo Hospitalario Universitario de A Coruña (CHUAC), Instituto de Investigación Biomédica de A Coruña (INIBIC), A Coruña, Spain.,Microbiome and Health, Faculty of Science, University of A Coruña, A Coruña, Spain
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38
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Gedefie A, Demsis W, Ashagrie M, Kassa Y, Tesfaye M, Tilahun M, Bisetegn H, Sahle Z. Acinetobacter baumannii Biofilm Formation and Its Role in Disease Pathogenesis: A Review. Infect Drug Resist 2021; 14:3711-3719. [PMID: 34531666 PMCID: PMC8439624 DOI: 10.2147/idr.s332051] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 09/02/2021] [Indexed: 01/01/2023] Open
Abstract
Acinetobacter species, particularly Acinetobacter baumannii, is the first pathogen on the critical priority list of pathogens for novel antibiotics to become a "red-alert" human pathogen. Acinetobacter baumannii is an emerging global antibiotic-resistant gram-negative bacteria that most typically causes biofilm-associated infections such as ventilator-associated pneumonia and catheter-related infection, both of which are resistant to antibiotic therapy. A. baumannii's capacity to develop antibiotic resistance mechanisms allows the organism to thrive in hospital settings, facilitating the global spread of multidrug-resistant strains. Although Acinetobacter infections are quickly expanding throughout hospital environments around the world, the highest concentration of infections occurs in intensive care units (ICUs). Biofilms are populations of bacteria on biotic or abiotic surfaces that are encased in the extracellular matrix and play a crucial role in pathogenesis, making treatment options more difficult. Even though a variety of biological and environmental elements are involved in the production of A. baumannii biofilms, glucose is the most important component. Biofilm-mediated A. baumannii infections are the most common type of A. baumannii infection associated with medical equipment, and they are extremely difficult to treat. As a result, health care workers (HCWs) should focus on infection prevention and safety actions to avoid A. baumannii biofilm-related infections caused by medical devices, and they should be very selective when using treatments in combination with anti-biofilms. Therefore, this review discusses biofilm formation in A. baumannii, its role in disease pathogenesis, and its antimicrobial resistance mechanism.
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Affiliation(s)
- Alemu Gedefie
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Wondmagegn Demsis
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Melaku Ashagrie
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Yeshimebet Kassa
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Melkam Tesfaye
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Mihret Tilahun
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Habtye Bisetegn
- Department of Medical Laboratory Sciences, College of Medicine and Health Science, Wollo University, Dessie, Ethiopia
| | - Zenawork Sahle
- Department of Medical Laboratory Sciences, Debre Birhan Health Science College, Debre Birhan, Ethiopia
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39
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Avery TM, Boone RL, Lu J, Spicer SK, Guevara MA, Moore RE, Chambers SA, Manning SD, Dent L, Marshall D, Damo SM, Townsend SD, Gaddy JA. Analysis of Antimicrobial and Antibiofilm Activity of Human Milk Lactoferrin Compared to Bovine Lactoferrin against Multidrug Resistant and Susceptible Acinetobacter baumannii Clinical Isolates. ACS Infect Dis 2021; 7:2116-2126. [PMID: 34105954 DOI: 10.1021/acsinfecdis.1c00087] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen that causes severe infections in immunocompromised patients. The emergence of multi- and pan-drug resistant strains of A. baumannii from clinical sources has confounded treatment and enhanced morbidity and mortality associated with these infections. One way that A. baumannii circumnavigates environmental and antimicrobial challenge is by forming tertiary architectural structures of cells known as biofilms. Biofilm-inhibiting molecules could be deployed as a potential chemotherapeutic strategy to inhibit or disrupt A. baumannii biofilms and mitigate adverse outcomes due to infection. Lactoferrin is an innate immune glycoprotein produced in high concentrations in both human and bovine milk which has previously been shown to have antibacterial and antibiofilm activities. We sought to test lactoferrin against a bank of clinical isolates of A. baumannii to determine changes in bacterial growth or biofilm formation. Our results indicate that human lactoferrin has slightly more potent antibacterial activities than bovine lactoferrin against certain strains of A. baumannii and that these effects are associated with anatomical site of isolation. Additionally, we have shown that both bovine and human lactoferrin can inhibit A. baumannii biofilm formation and that these effects are associated with anatomical site of isolation and whether the strain forms robust or weak biofilms.
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Affiliation(s)
- Tyra M. Avery
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, Tennessee 37208, United States
| | - RaNashia L. Boone
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, Tennessee 37208, United States
| | - Jacky Lu
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, United States
| | - Sabrina K. Spicer
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Miriam A. Guevara
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, United States
| | - Rebecca E. Moore
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Schuyler A. Chambers
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Shannon D. Manning
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Leon Dent
- Department of Pathology, Anatomy, and Cell Biology, Meharry Medical College, Nashville, Tennessee 37208, United States
- Trauma Services, Phoebe Putney Memorial Hospital, Albany, Georgia 31701, United States
| | - Dana Marshall
- Department of Pathology, Anatomy, and Cell Biology, Meharry Medical College, Nashville, Tennessee 37208, United States
| | - Steven M. Damo
- Department of Life and Physical Sciences, Fisk University, Talley-Brady Hall, 1000 17th Ave. N, Nashville, Tennessee 37208, United States
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37205, United States
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37205, United States
| | - Steven D. Townsend
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jennifer A. Gaddy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, United States
- Department of Medicine, Division of Infectious Diseases, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
- Department of Veterans Affairs, Tennessee Valley Healthcare Systems, Nashville, Tennessee 37212, United States
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40
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Bohac TJ, Fang L, Banas VS, Giblin DE, Wencewicz TA. Synthetic Mimics of Native Siderophores Disrupt Iron Trafficking in Acinetobacter baumannii. ACS Infect Dis 2021; 7:2138-2151. [PMID: 34110766 DOI: 10.1021/acsinfecdis.1c00119] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Many pathogenic bacteria biosynthesize and excrete small molecule metallophores, known as siderophores, that are used to extract ferric iron from host sources to satisfy nutritional need. Native siderophores are often structurally complex multidentate chelators that selectively form high-affinity octahedral ferric iron complexes with defined chirality recognizable by cognate protein receptors displayed on the bacterial cell surface. Simplified achiral analogues can serve as synthetically tractable siderophore mimics with potential utility as chemical probes and therapeutic agents to better understand and treat bacterial infections, respectively. Here, we demonstrate that synthetic spermidine-derived mixed ligand bis-catecholate monohydroxamate siderophores (compounds 1-3) are versatile structural and biomimetic analogues of two native siderophores, acinetobactin and fimsbactin, produced by Acinetobacter baumannii, a multidrug-resistant Gram-negative human pathogen. The metal-free and ferric iron complexes of the synthetic siderophores are growth-promoting agents of A. baumannii, while the Ga(III)-complexes are potent growth inhibitors of A. baumannii with MIC values <1 μM. The synthetic siderophores compete with native siderophores for uptake in A. baumannii and maintain comparable apparent binding affinities for ferric iron (KFe) and the siderophore-binding protein BauB (Kd). Our findings provide new insight to guide the structural fine-tuning of these compounds as siderophore-based therapeutics targeting pathogenic strains of A. baumannii.
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Affiliation(s)
- Tabbetha J. Bohac
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Luting Fang
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Victoria S. Banas
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Daryl E. Giblin
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
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41
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Kim K, Islam M, Jung HW, Lim D, Kim K, Lee SG, Park C, Lee JC, Shin M. ppGpp signaling plays a critical role in virulence of Acinetobacter baumannii. Virulence 2021; 12:2122-2132. [PMID: 34375563 PMCID: PMC8366539 DOI: 10.1080/21505594.2021.1961660] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acinetobacter baumannii, a major nosocomial pathogen, survives in diverse hospital environments, and its multidrug resistance is a major concern. The ppGpp-dependent stringent response mediates the reprogramming of genes with diverse functions in several bacteria. We investigated whether ppGpp is involved in A. baumannii’s pathogenesis by examining biofilm formation, surface motility, adhesion, invasion, and mouse infection studies. Transcriptome analysis of early stationary phase cultures revealed 498 differentially-expressed genes (≥ 2-fold change) in a ppGpp-deficient A. baumannii strain; 220 and 278 genes were up and downregulated, respectively. Csu operon expression, important in pilus biosynthesis during early biofilm formation, was significantly reduced in the ppGpp-deficient strain. Our findings suggest that ppGpp signaling influences A. baumannii biofilm formation, surface motility, adherence, and virulence. We showed the association between ppGpp and pathogenicity in A. baumannii for the first time; ppGpp may be a novel antivirulence target in A. baumannii.
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Affiliation(s)
- Kyeongmin Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Maidul Islam
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Hye-Won Jung
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Daejin Lim
- Department of Microbiology, Chonnam National University Medical School, Gwangju South Korea
| | - Kwangsoo Kim
- Department of Microbiology, Chonnam National University Medical School, Gwangju South Korea
| | - Sung-Gwon Lee
- School of Biological Sciences and Technology, Chonnam National University, Gwangju South Korea
| | - Chungoo Park
- School of Biological Sciences and Technology, Chonnam National University, Gwangju South Korea
| | - Je Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Jung-gu, Daegu, South Korea
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42
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Cameranesi MM, Kurth D, Repizo GD. Acinetobacter defence mechanisms against biological aggressors and their use as alternative therapeutic applications. Crit Rev Microbiol 2021; 48:21-41. [PMID: 34289313 DOI: 10.1080/1040841x.2021.1939266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii being the species of greatest worldwide concern due to its multi-drug resistance and the recent appearance of hyper-virulent strains in the clinical setting. Colonisation of this environment is associated with a multitude of bacterial factors, and the molecular features that promote environmental persistence in abiotic surfaces, including intrinsic desiccation resistance, biofilm formation and motility, have been previously addressed. On the contrary, mechanisms enabling Acinetobacter spp. survival when faced against other biological competitors are starting to be characterised. Among them, secretion systems (SS) of different types, such as the T5bSS (Contact-dependent inhibition systems) and the T6SS, confer adaptive advantages against bacterial aggressors. Regarding mechanisms of defence against bacteriophages, such as toxin-antitoxin, restriction-modification, Crispr-Cas and CBASS, among others, have been identified but remain poorly characterised. In view of this, we aimed to summarise the present knowledge on defence mechanisms that enable niche establishment in members of the Acinetobacter genus. Different proposals are also described for the use of some components of these systems as molecular tools to treat Acinetobacter infections.
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Affiliation(s)
- María Marcela Cameranesi
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Daniel Kurth
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI, CONICET), San Miguel de Tucumán, Argentina
| | - Guillermo Daniel Repizo
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Mat Rahim N, Lee H, Strych U, AbuBakar S. Facing the challenges of multidrug-resistant Acinetobacter baumannii: progress and prospects in the vaccine development. Hum Vaccin Immunother 2021; 17:3784-3794. [PMID: 34106809 PMCID: PMC8437540 DOI: 10.1080/21645515.2021.1927412] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In 2017, the World Health Organization (WHO) named A. baumannii as one of the three antibiotic-resistant bacterial species on its list of global priority pathogens in dire need of novel and effective treatment. With only polymyxin and tigecycline antibiotics left as last-resort treatments, the need for novel alternative approaches to the control of this bacterium becomes imperative. Vaccines against numerous bacteria have had impressive records in reducing the burden of the respective diseases and addressing antimicrobial resistance; as in the case of Haemophilus influenzae type b . A similar approach could be appropriate for A. baumannii. Toward this end, several potentially protective antigens against A. baumannii were identified and evaluated as vaccine antigen candidates. A licensed vaccine for the bacteria, however, is still not in sight. Here we explore and discuss challenges in vaccine development against A. baumannii and the promising approaches for improving the vaccine development process.
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Affiliation(s)
- NorAziyah Mat Rahim
- Tropical Infectious Diseases Research and Education Center (TIDREC), Universiti Malaya, Kuala Lumpur, Malaysia.,Texas Children's Hospital Center for Vaccine Development, Baylor College of Medicine, Houston, TX, USA.,Virology Unit, Institute for Medical Research, National Institute of Health Complex, Setia Alam, Malaysia
| | - HaiYen Lee
- Tropical Infectious Diseases Research and Education Center (TIDREC), Universiti Malaya, Kuala Lumpur, Malaysia
| | - Ulrich Strych
- Texas Children's Hospital Center for Vaccine Development, Baylor College of Medicine, Houston, TX, USA
| | - Sazaly AbuBakar
- Tropical Infectious Diseases Research and Education Center (TIDREC), Universiti Malaya, Kuala Lumpur, Malaysia
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Ma C, McClean S. Mapping Global Prevalence of Acinetobacter baumannii and Recent Vaccine Development to Tackle It. Vaccines (Basel) 2021; 9:vaccines9060570. [PMID: 34205838 PMCID: PMC8226933 DOI: 10.3390/vaccines9060570] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/16/2021] [Accepted: 05/22/2021] [Indexed: 12/23/2022] Open
Abstract
Acinetobacter baumannii is a leading cause of nosocomial infections that severely threaten public health. The formidable adaptability and resistance of this opportunistic pathogen have hampered the development of antimicrobial therapies which consequently leads to very limited treatment options. We mapped the global prevalence of multidrug-resistant A. baumannii and showed that carbapenem-resistant A. baumannii is widespread throughout Asia and the Americas. Moreover, when antimicrobial resistance rates of Acinetobacter spp. exceed a threshold level, the proportion of A. baumannii isolates from clinical samples surges. Therefore, vaccines represent a realistic alternative strategy to tackle this pathogen. Research into anti-A. baumannii vaccines have enhanced in the past decade and multiple antigens have been investigated preclinically with varying results. This review summarises the current knowledge of virulence factors relating to A. baumannii–host interactions and its implication in vaccine design, with a view to understanding the current state of A. baumannii vaccine development and the direction of future efforts.
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Khasheii B, Mahmoodi P, Mohammadzadeh A. Siderophores: Importance in bacterial pathogenesis and applications in medicine and industry. Microbiol Res 2021; 250:126790. [PMID: 34098495 DOI: 10.1016/j.micres.2021.126790] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/14/2021] [Accepted: 05/24/2021] [Indexed: 12/21/2022]
Abstract
Iron is an essential element for all microorganisms. Siderophores are low-weight, high-affinity iron chelating molecules produced in response to iron deficiency by Gram-positive and Gram-negative bacteria which also known as essential virulence factors of bacteria. Several studies have indicated that defective production and/or function of these molecules as well as iron acquisition systems in pathogens are associated with a reduction in pathogenicity of bacteria. Because of their potential role in various biological pathways, siderophores have been received special attention as secondary metabolites. Siderophores can detect iron levels in a variety of environments with a biosensor function. In medicine, siderophores are used to deliver antibiotics (Trojan horse strategy) to resistant bacteria and to treat diseases such as cancer and malaria. In this review, we discuss the iron acquisition pathways in Gram-positive and -negative bacteria, importance of siderophore production in pathogenesis of bacteria, classification of siderophores, and main applications of siderophores in medicine and industry.
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Affiliation(s)
- Behnoush Khasheii
- Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamedan, Iran
| | - Pezhman Mahmoodi
- Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamedan, Iran.
| | - Abdolmajid Mohammadzadeh
- Department of Pathobiology, Faculty of Veterinary Science, Bu-Ali Sina University, Hamedan, Iran
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Klebba PE, Newton SMC, Six DA, Kumar A, Yang T, Nairn BL, Munger C, Chakravorty S. Iron Acquisition Systems of Gram-negative Bacterial Pathogens Define TonB-Dependent Pathways to Novel Antibiotics. Chem Rev 2021; 121:5193-5239. [PMID: 33724814 PMCID: PMC8687107 DOI: 10.1021/acs.chemrev.0c01005] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Iron is an indispensable metabolic cofactor in both pro- and eukaryotes, which engenders a natural competition for the metal between bacterial pathogens and their human or animal hosts. Bacteria secrete siderophores that extract Fe3+ from tissues, fluids, cells, and proteins; the ligand gated porins of the Gram-negative bacterial outer membrane actively acquire the resulting ferric siderophores, as well as other iron-containing molecules like heme. Conversely, eukaryotic hosts combat bacterial iron scavenging by sequestering Fe3+ in binding proteins and ferritin. The variety of iron uptake systems in Gram-negative bacterial pathogens illustrates a range of chemical and biochemical mechanisms that facilitate microbial pathogenesis. This document attempts to summarize and understand these processes, to guide discovery of immunological or chemical interventions that may thwart infectious disease.
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Affiliation(s)
- Phillip E Klebba
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | - Salete M C Newton
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | - David A Six
- Venatorx Pharmaceuticals, Inc., 30 Spring Mill Drive, Malvern, Pennsylvania 19355, United States
| | - Ashish Kumar
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | - Taihao Yang
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | - Brittany L Nairn
- Department of Biological Sciences, Bethel University, 3900 Bethel Drive, St. Paul, Minnesota 55112, United States
| | - Colton Munger
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas 66506, United States
| | - Somnath Chakravorty
- Jacobs School of Medicine and Biomedical Sciences, SUNY Buffalo, Buffalo, New York 14203, United States
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Nutman A, Temkin E, Lellouche J, Rakovitsky N, Hameir A, Daikos G, Durante-Mangoni E, Pavleas I, Dishon Y, Petersiel N, Yahav D, Eliakim N, Bernardo M, Iossa D, Friberg LE, Theuretzbacher U, Leibovici L, Paul M, Carmeli Y. In vivo fitness of carbapenem-resistant Acinetobacter baumannii strains in murine infection is associated with treatment failure in human infections. Clin Microbiol Infect 2021; 28:73-78. [PMID: 33984488 DOI: 10.1016/j.cmi.2021.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/14/2021] [Accepted: 05/01/2021] [Indexed: 12/01/2022]
Abstract
OBJECTIVES Mortality among patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections varies between studies. We examined whether in vivo fitness of CRAB strains is associated with clinical outcomes in patients with CRAB infections. METHODS Isolates were collected from patients enrolled in the AIDA trial with hospital-acquired pneumonia, bloodstream infections and/or urinary tract infections caused by CRAB. The primary outcome was 14-day clinical failure, defined as failure to meet all criteria: alive; haemodynamically stable; improved or stable Sequential Organ Failure Assessment (SOFA) score; improved or stable oxygenation; and microbiological cure of bacteraemia. The secondary outcome was 14-day mortality. We tested in vivo growth using a neutropenic murine thigh infection model. Fitness was defined based on the CFU count 24 hours after injection of an inoculum of 105 CFU. We used mixed-effects logistic regression to test the association between fitness and the two outcomes. RESULTS The sample included 266 patients; 215 (80.8%) experienced clinical failure. CRAB fitness ranged from 5.23 to 10.08 log CFU/g. The odds of clinical failure increased by 62% for every 1-log CFU/g increase in fitness (OR 1.62, 95% CI 1.04-2.52). After adjusting for age, Charlson score, SOFA score and acquisition in the intensive care unit, fitness remained significant (adjusted OR 1.63, 95% CI 1.03-2.59). CRAB fitness had a similar effect on 14-day mortailty, although the association was not statistically significant (OR 1.56, 95% CI 0.95-2.57). It became significant after adjusting for age, Charlson score, SOFA score and recent surgery (adjusted OR 1.88, 95% CI 1.09-3.25). CONCLUSIONS In vivo CRAB fitness was associated with clinical failure in patients with CRAB infection.
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Affiliation(s)
- Amir Nutman
- Division of Epidemiology and Preventive Medicine, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel; National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Elizabeth Temkin
- Division of Epidemiology and Preventive Medicine, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel; National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Jonathan Lellouche
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Nadya Rakovitsky
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - Amichay Hameir
- National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel
| | - George Daikos
- First Department of Medicine, Laikon General Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Emanuele Durante-Mangoni
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", AORN Dei Colli-Monaldi Hospital, Napoli, Italy
| | - Ioannis Pavleas
- Intensive Care Unit, Laikon General Hospital, Athens, Greece
| | - Yael Dishon
- Institute of Infectious Diseases, Rambam Health Care Campus, Haifa, Israel; The Cheryl Spencer Institute for Nursing Research, University of Haifa, Haifa, Israel
| | - Neta Petersiel
- Institute of Infectious Diseases, Rambam Health Care Campus, Haifa, Israel
| | - Dafna Yahav
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Infectious Diseases Unit, Rabin Medical Centre, Beilinson Hospital, Petah Tikva, Israel
| | - Noa Eliakim
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Medicine E, Rabin Medical Centre, Beilinson Hospital, Petah Tikva, Israel
| | - Mariano Bernardo
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", AORN Dei Colli-Monaldi Hospital, Napoli, Italy
| | - Domenico Iossa
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", AORN Dei Colli-Monaldi Hospital, Napoli, Italy
| | - Lena E Friberg
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | | | - Leonard Leibovici
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Medicine E, Rabin Medical Centre, Beilinson Hospital, Petah Tikva, Israel
| | - Mical Paul
- Institute of Infectious Diseases, Rambam Health Care Campus, Haifa, Israel; The Ruth and Bruce Rappaport Faculty of Medicine, Techion - Israel Institute of Technology, Haifa, Israel
| | - Yehuda Carmeli
- Division of Epidemiology and Preventive Medicine, Tel Aviv Sourasky Medical Centre, Tel Aviv, Israel; National Institute for Antibiotic Resistance and Infection Control, Israel Ministry of Health, Tel Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Zheng Y, Xu N, Pang J, Han H, Yang H, Qin W, Zhang H, Li W, Wang H, Chen Y. Colonization With Extensively Drug-Resistant Acinetobacter baumannii and Prognosis in Critically Ill Patients: An Observational Cohort Study. Front Med (Lausanne) 2021; 8:667776. [PMID: 33996866 PMCID: PMC8119758 DOI: 10.3389/fmed.2021.667776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 04/06/2021] [Indexed: 12/16/2022] Open
Abstract
Background: Acinetobacter baumannii is one of the most frequently isolated opportunistic pathogens in intensive care units (ICUs). Extensively drug-resistant A. baumannii (XDR-AB) strains lack susceptibility to almost all antibiotics and pose a heavy burden on healthcare institutions. In this study, we evaluated the impact of XDR-AB colonization on both the short-term and long-term survival of critically ill patients. Methods: We prospectively enrolled patients from two adult ICUs in Qilu Hospital of Shandong University from March 2018 through December 2018. Using nasopharyngeal and perirectal swabs, we evaluated the presence of XDR-AB colonization. Participants were followed up for 6 months. The primary endpoints were 28-day and 6-month mortality after ICU admission. The overall survival rate was estimated by the Kaplan-Meier method. We identified risk factors associated with 28-day and 6-month mortality using the logistic regression model and a time-dependent Cox regression model, respectively. Results: Out of 431 patients, 77 were colonized with XDR-AB. Based on the Kaplan-Meier curve results, the overall survival before 28 days did not differ by colonization status; however, a significantly lower overall survival rate was obtained at 6 months in colonized patients. Univariate and multivariate analysis results confirmed that XDR-AB colonization was not associated with 28-day mortality, but was an independent risk factor of lower overall survival at 6 months (HR = 1.749, 95% CI = 1.174-2.608). Conclusions: XDR-AB colonization has no effect on short-term overall survival, but is associated with lower long-term overall survival in critically ill patients.
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Affiliation(s)
- Yue Zheng
- Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, Institute of Emergency and Critical Care Medicine of Shandong University, Chest Pain Center, Qilu Hospital of Shandong University, Jinan, China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Jinan, China
- Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Shandong Provincial Engineering Laboratory for Emergency and Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
- The Key Laboratory of Cardiovascular Remodeling and Function Research, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, China
| | - Nana Xu
- Cardiosurgery Care Unit, Department of Cardiosurgery, Qilu Hospital of Shandong University, Jinan, China
| | - Jiaojiao Pang
- Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, Institute of Emergency and Critical Care Medicine of Shandong University, Chest Pain Center, Qilu Hospital of Shandong University, Jinan, China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Jinan, China
- Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Shandong Provincial Engineering Laboratory for Emergency and Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
- The Key Laboratory of Cardiovascular Remodeling and Function Research, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, China
| | - Hui Han
- Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
| | - Hongna Yang
- Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
| | - Weidong Qin
- Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
| | - Hui Zhang
- Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
| | - Wei Li
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
| | - Hao Wang
- Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, Institute of Emergency and Critical Care Medicine of Shandong University, Chest Pain Center, Qilu Hospital of Shandong University, Jinan, China
- Department of Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
- Department of Pharmacology, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Yuguo Chen
- Shandong Provincial Clinical Research Center for Emergency and Critical Care Medicine, Institute of Emergency and Critical Care Medicine of Shandong University, Chest Pain Center, Qilu Hospital of Shandong University, Jinan, China
- Department of Emergency Medicine, Qilu Hospital of Shandong University, Jinan, China
- Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Shandong Provincial Engineering Laboratory for Emergency and Critical Care Medicine, Qilu Hospital of Shandong University, Jinan, China
- The Key Laboratory of Cardiovascular Remodeling and Function Research, The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, China
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Pimentel C, Le C, Tuttobene MR, Subils T, Martinez J, Sieira R, Papp-Wallace KM, Keppetipola N, Bonomo RA, Actis LA, Tolmasky ME, Ramirez MS. Human Pleural Fluid and Human Serum Albumin Modulate the Behavior of a Hypervirulent and Multidrug-Resistant (MDR) Acinetobacter baumannii Representative Strain. Pathogens 2021; 10:pathogens10040471. [PMID: 33924559 PMCID: PMC8069197 DOI: 10.3390/pathogens10040471] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 02/07/2023] Open
Abstract
Acinetobacter baumannii is a nosocomial pathogen capable of causing serious infections associated with high rates of morbidity and mortality. Due to its antimicrobial drug resistance profile, A. baumannii is categorized as an urgent priority pathogen by the Centers for Disease Control and Prevention in the United States and a priority group 1 critical microorganism by the World Health Organization. Understanding how A. baumannii adapts to different host environments may provide critical insights into strategically targeting this pathogen with novel antimicrobial and biological therapeutics. Exposure to human fluids was previously shown to alter the gene expression profile of a highly drug-susceptible A. baumannii strain A118 leading to persistence and survival of this pathogen. Herein, we explore the impact of human pleural fluid (HPF) and human serum albumin (HSA) on the gene expression profile of a highly multi-drug-resistant strain of A. baumannii AB5075. Differential expression was observed for ~30 genes, whose products are involved in quorum sensing, quorum quenching, iron acquisition, fatty acid metabolism, biofilm formation, secretion systems, and type IV pilus formation. Phenotypic and further transcriptomic analysis using quantitative RT-PCR confirmed RNA-seq data and demonstrated a distinctive role of HSA as the molecule involved in A. baumannii’s response.
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Affiliation(s)
- Camila Pimentel
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Casin Le
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Marisel R. Tuttobene
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Tomas Subils
- Instituto de Procesos Biotecnológicos y Químicos de Rosario (IPROBYQ, CONICET-UNR), Rosario S2002LRK, Argentina;
| | - Jasmine Martinez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Rodrigo Sieira
- Fundación Instituto Leloir—IIBBA CONICET, Buenos Aires C1405BWE, Argentina;
| | - Krisztina M. Papp-Wallace
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; (K.M.P.-W.); (R.A.B.)
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Niroshika Keppetipola
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, CA 92831-3599, USA;
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH 44106, USA; (K.M.P.-W.); (R.A.B.)
- Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, OH 44106, USA
| | - Luis A. Actis
- Department of Microbiology, Miami University, Oxford, OH 45056, USA;
| | - Marcelo E. Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
| | - Maria Soledad Ramirez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, CA 92831-3599, USA; (C.P.); (C.L.); (M.R.T.); (J.M.); (M.E.T.)
- Correspondence: ; Tel.: +1-657-278-4562
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50
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Grier JT, Arivett BA, Ramírez MS, Chosed RJ, Bigner JA, Ohneck EJ, Metz ML, Wood CR, Arce S, Tartaro A, Relich RF, Actis LA, Fiester SE. Two Acinetobacter baumannii Isolates Obtained From a Fatal Necrotizing Fasciitis Infection Display Distinct Genomic and Phenotypic Characteristics in Comparison to Type Strains. Front Cell Infect Microbiol 2021; 11:635673. [PMID: 33912474 PMCID: PMC8072282 DOI: 10.3389/fcimb.2021.635673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/11/2021] [Indexed: 11/23/2022] Open
Abstract
Acinetobacter baumannii has been recognized as a critical pathogen that causes severe infections worldwide not only because of the emergence of extensively drug-resistant (XDR) derivatives, but also because of its ability to persist in medical environments and colonize compromised patients. While there are numerous reports describing the mechanisms by which this pathogen acquires resistance genes, little is known regarding A. baumannii’s virulence functions associated with rare manifestations of infection such as necrotizing fasciitis, making the determination and implementation of alternative therapeutic targets problematic. To address this knowledge gap, this report describes the analysis of the NFAb-1 and NFAb-2 XDR isolates, which were obtained at two time points during a fatal case of necrotizing fasciitis, at the genomic and functional levels. The comparative genomic analysis of these isolates with the ATCC 19606T and ATCC 17978 strains showed that the NFAb-1 and NFAb-2 isolates are genetically different from each other as well as different from the ATCC 19606T and ATCC 17978 clinical isolates. These genomic differences could be reflected in phenotypic differences observed in these NFAb isolates. Biofilm, cell viability and flow cytometry assays indicate that all tested strains caused significant decreases in A549 human alveolar epithelial cell viability with ATCC 17978, NFAb-1 and NFAb-2 producing significantly less biofilm and significantly more hemolysis and capacity for intracellular invasion than ATCC 19606T. NFAb-1 and NFAb-2 also demonstrated negligible surface motility but significant twitching motility compared to ATCC 19606T and ATCC 17978, likely due to the presence of pili exceeding 2 µm in length, which are significantly longer and different from those previously described in the ATCC 19606T and ATCC 17978 strains. Interestingly, infection with cells of the NFAb-1 isolate, which were obtained from a premortem blood sample, lead to significantly higher mortality rates than NFAb-2 bacteria, which were obtained from postmortem tissue samples, when tested using the Galleria mellonella in vivo infection model. These observations suggest potential changes in the virulence phenotype of the A. baumannii necrotizing fasciitis isolates over the course of infection by mechanisms and cell processes that remain to be identified.
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Affiliation(s)
- Jennifer T Grier
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Brock A Arivett
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, United States
| | - Maria S Ramírez
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States
| | - Renee J Chosed
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Jessica A Bigner
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States
| | - Emily J Ohneck
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Maeva L Metz
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Cecily R Wood
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Sergio Arce
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States.,Cancer Institute, Prisma Health, Greenville, SC, United States
| | - Andrea Tartaro
- Computer Science Department, Furman University, Greenville, SC, United States
| | - Ryan F Relich
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Luis A Actis
- Department of Microbiology, Miami University, Oxford, OH, United States
| | - Steven E Fiester
- Department of Biomedical Sciences, University of South Carolina School of Medicine Greenville, Greenville, SC, United States.,Department of Pathology, Prisma Health, Greenville, SC, United States
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