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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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Jeffreys S, Tompkins MP, Aki J, Papp SB, Chambers JP, Guentzel MN, Hung CY, Yu JJ, Arulanandam BP. Development and Evaluation of an Immunoinformatics-Based Multi-Peptide Vaccine against Acinetobacter baumannii Infection. Vaccines (Basel) 2024; 12:358. [PMID: 38675740 PMCID: PMC11054912 DOI: 10.3390/vaccines12040358] [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: 02/27/2024] [Revised: 03/21/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024] Open
Abstract
Multi-drug-resistant (MDR) Acinetobacter baumannii is an opportunistic pathogen associated with hospital-acquired infections. Due to its environmental persistence, virulence, and limited treatment options, this organism causes both increased patient mortality and incurred healthcare costs. Thus, prophylactic vaccination could be ideal for intervention against MDR Acinetobacter infection in susceptible populations. In this study, we employed immunoinformatics to identify peptides containing both putative B- and T-cell epitopes from proteins associated with A. baumannii pathogenesis. A novel Acinetobacter Multi-Epitope Vaccine (AMEV2) was constructed using an A. baumannii thioredoxin A (TrxA) leading protein sequence followed by five identified peptide antigens. Antisera from A. baumannii infected mice demonstrated reactivity to rAMEV2, and subcutaneous immunization of mice with rAMEV2 produced high antibody titer against the construct as well as peptide components. Immunization results in increased frequency of IL-4-secreting splenocytes indicative of a Th2 response. AMEV2-immunized mice were protected against intranasal challenge with a hypervirulent strain of A. baumannii and demonstrated reduced bacterial burden at 48 h. In contrast, all mock vaccinated mice succumbed to infection within 3 days. Results presented here provide insight into the effectiveness of immunoinformatic-based vaccine design and its potential as an effective strategy to combat the rise of MDR pathogens.
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Affiliation(s)
- Sean Jeffreys
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Megan P. Tompkins
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Jadelynn Aki
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Sara B. Papp
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - James P. Chambers
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - M. Neal Guentzel
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Chiung-Yu Hung
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Jieh-Juen Yu
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
| | - Bernard P. Arulanandam
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA; (S.J.); (M.P.T.); (J.A.); (J.P.C.); (M.N.G.); (C.-Y.H.)
- Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
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Li S, Yang W, Mo J, Wang Y, Lu C, Gao Y, Li Y, Sun K. Adaptive responses and metabolic strategies of Novosphingobium sp. ES2-1-17β-estradiol analyzed through integration of genomic and proteomic approaches. JOURNAL OF HAZARDOUS MATERIALS 2024; 461:132543. [PMID: 37717446 DOI: 10.1016/j.jhazmat.2023.132543] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/03/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023]
Abstract
Environmental 17β-estradiol (E2) can cause potential harm to ecological balance and human health. Novosphingobium sp. ES2-1 is an E2-degrading bacterium previously obtained, which converts E2 to estrone (E1) and then to 4-hydroxyestrone (4-OH-E1) followed by oxidation to form metabolites with long-chain structure during upstream degradation. Herein, we found that intracellular enzymes were the major contributors to E2 biodegradation by strain ES2-1. A total of 243 proteins were dys-expressed under E2 condition, 123 were up-regulated and 120 were down-regulated thereinto. The up-regulated members of ABC transport systems, aromatics degradation, and fatty acid degradation indicated a reinforced transfer and utilization of E2. Cytochrome P450 monooxygenase (EstP1), 2-keto-4-pentenoate hydratase, pyruvate dehydrogenase, acetyl-CoA acetyltransferase, TonB-dependent receptor were involved in E2 catabolism. During downstream degradation, the metabolites with long-chain structure were decomposed adopting β-oxidation pattern and ultimately entered the TCA cycle; 2-keto-4-pentenoic acid might be an emblematic product of such process. Furthermore, E2 converting to E1 was catalyzed by 17β-dehydrogenase probably encoded by IM701_16645 or IM701_16910; 4-OH-E1 meta-cleavage was catalyzed by a dioxygenase encoded by IM701_20340 or IM701_21000 or IM701_09625. Our study provided an in-depth insight into the adaptive responses and metabolic strategies of Novosphingobium to E2.
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Affiliation(s)
- Shunyao Li
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Jiulong Road 111, Hefei 230601, China.
| | - Wei Yang
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Jiulong Road 111, Hefei 230601, China
| | - Jingjing Mo
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Jiulong Road 111, Hefei 230601, China
| | - Yubing Wang
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Jiulong Road 111, Hefei 230601, China
| | - Chao Lu
- National Agricultural Experimental Station for Agricultural Environment, Luhe, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, PR China
| | - Yanzheng Gao
- Institute of Organic Contaminant Control and Soil Remediation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
| | - Yucheng Li
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, Anhui University, Jiulong Road 111, Hefei 230601, China
| | - Kai Sun
- Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, Anhui, China.
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Naka H, Haygood MG. The dual role of TonB genes in turnerbactin uptake and carbohydrate utilization in the shipworm symbiont Teredinibacter turnerae. Appl Environ Microbiol 2023; 89:e0074423. [PMID: 38009998 PMCID: PMC10734418 DOI: 10.1128/aem.00744-23] [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: 05/18/2023] [Accepted: 10/01/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE This study highlights diversity in iron acquisition and regulation in bacteria. The mechanisms of iron acquisition and its regulation in Teredinibacter turnerae, as well as its connection to cellulose utilization, a hallmark phenotype of T. turnerae, expand the paradigm of bacterial iron acquisition. Two of the four TonB genes identified in T. turnerae exhibit functional redundancy and play a crucial role in siderophore-mediated iron transport. Unlike typical TonB genes in bacteria, none of the TonB genes in T. turnerae are clearly iron regulated. This unusual regulation could be explained by another important finding in this study, namely, that the two TonB genes involved in iron transport are also essential for cellulose utilization as a carbon source, leading to the expression of TonB genes even under iron-rich conditions.
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Affiliation(s)
- Hiroaki Naka
- Department of Medicinal Chemistry, The University of Utah, Salt Lake City, Utah, USA
- Division of Genetics, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, USA
| | - Margo G. Haygood
- Department of Medicinal Chemistry, The University of Utah, Salt Lake City, Utah, USA
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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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Braun V, Ratliff AC, Celia H, Buchanan SK. Energization of Outer Membrane Transport by the ExbB ExbD Molecular Motor. J Bacteriol 2023; 205:e0003523. [PMID: 37219427 PMCID: PMC10294619 DOI: 10.1128/jb.00035-23] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023] Open
Abstract
The outer membranes (OM) of Gram-negative bacteria contain a class of proteins (TBDTs) that require energy for the import of nutrients and to serve as receptors for phages and protein toxins. Energy is derived from the proton motif force (pmf) of the cytoplasmic membrane (CM) through the action of three proteins, namely, TonB, ExbB, and ExbD, which are located in the CM and extend into the periplasm. The leaky phenotype of exbB exbD mutants is caused by partial complementation by homologous tolQ tolR. TonB, ExbB, and ExbD are genuine components of an energy transmission system from the CM into the OM. Mutant analyses, cross-linking experiments, and most recently X-ray and cryo-EM determinations were undertaken to arrive at a model that describes the energy transfer from the CM into the OM. These results are discussed in this paper. ExbB forms a pentamer with a pore inside, in which an ExbD dimer resides. This complex harvests the energy of the pmf and transmits it to TonB. TonB interacts with the TBDT at the TonB box, which triggers a conformational change in the TBDT that releases bound nutrients and opens the pore, through which nutrients pass into the periplasm. The structurally altered TBDT also changes the interactions of its periplasmic signaling domain with anti-sigma factors, with the consequence being that the sigma factors initiate transcription.
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Affiliation(s)
- Volkmar Braun
- Max-Planck-Institute for Biology, Department of Protein Evolution, Tübingen, Germany
| | - Anna C. Ratliff
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, NIH, Maryland, Bethesda, USA
| | - Herve Celia
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, NIH, Maryland, Bethesda, USA
| | - Susan K. Buchanan
- Laboratory of Molecular Biology, National Institute of Diabetes & Digestive & Kidney Diseases, NIH, Maryland, Bethesda, USA
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Naka H, Haygood MG. The dual role of TonB genes in turnerbactin uptake and carbohydrate utilization in the shipworm symbiont Teredinibacter turnerae. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.23.529781. [PMID: 36865190 PMCID: PMC9980095 DOI: 10.1101/2023.02.23.529781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Teredinibacter turnerae is an intracellular bacterial symbiont that resides in the gills of shipworms, wood-eating bivalve mollusks. This bacterium produces a catechol siderophore, turnerbactin, required for the survival of this bacterium under iron limiting conditions. The turnerbactin biosynthetic genes are contained in one of the secondary metabolite clusters conserved among T. turnerae strains. However, Fe(III)-turnerbactin uptake mechanisms are largely unknown. Here, we show that the first gene of the cluster, fttA a homologue of Fe(III)-siderophore TonB-dependent outer membrane receptor (TBDR) genes is indispensable for iron uptake via the endogenous siderophore, turnerbactin, as well as by an exogenous siderophore, amphi-enterobactin, ubiquitously produced by marine vibrios. Furthermore, three TonB clusters containing four tonB genes were identified, and two of these genes, tonB1b and tonB2, functioned not only for iron transport but also for carbohydrate utilization when cellulose was a sole carbon source. Gene expression analysis revealed that none of the tonB genes and other genes in those clusters were clearly regulated by iron concentration while turnerbactin biosynthesis and uptake genes were up-regulated under iron limiting conditions, highlighting the importance of tonB genes even in iron rich conditions, possibly for utilization of carbohydrates derived from cellulose.
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Affiliation(s)
- Hiroaki Naka
- Department of Medicinal Chemistry, the University of Utah
- Division of Genetics, Oregon National Primate Research Center, Oregon Health & Science University
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Stracquadanio S, Bonomo C, Marino A, Bongiorno D, Privitera GF, Bivona DA, Mirabile A, Bonacci PG, Stefani S. Acinetobacter baumannii and Cefiderocol, between Cidality and Adaptability. Microbiol Spectr 2022; 10:e0234722. [PMID: 36173300 PMCID: PMC9603721 DOI: 10.1128/spectrum.02347-22] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/07/2022] [Indexed: 01/04/2023] Open
Abstract
Among the bacterial species included in the ESKAPE group, Acinetobacter baumannii is of great interest due to its intrinsic and acquired resistance to many antibiotics and its ability to infect different body regions. Cefiderocol (FDC) is a novel cephalosporin that is active against Gram-negative bacteria, with promising efficacy for A. baumannii infections, but some studies have reported therapeutic failures even in the presence of susceptible strains. This study aims to investigate the interactions between FDC and 10 A. baumannii strains with different susceptibilities to this drug. We confirmed diverse susceptibility profiles, with resistance values close to the EUCAST-proposed breakpoints. The minimal bactericidal concentration (MBC)/MIC ratios demonstrated bactericidal activity of the drug, with ratio values of ≤4 for all of the strains except ATCC 19606; however, bacterial regrowth was evident after exposure to FDC, as were changes in the shapes of colonies and bacterial cells. A switch to a nonsusceptible phenotype in the presence of high FDC concentrations was found in 1 strain as an adaptation mechanism implemented to overcome the cidal activity of this antibiotic, which was confirmed by the presence of heteroresistant, unstable subpopulations in 8/10 samples. Genomic analyses revealed the presence of mutations in penicillin-binding protein 3 (PBP3) and TonB3 that were shared by all of the strains regardless of their resistance phenotype. Because our isolates harbored β-lactamase genes, β-lactamase inhibitors showed the ability to restore the antimicrobial activity of FDC despite the different nonsusceptibility levels of the tested strains. These in vitro results support the concept of using combination therapy to eliminate drug-adapted subpopulations and regain full FDC activity in this difficult-to-treat species. IMPORTANCE This work demonstrates the underrated presence of Acinetobacter baumannii heteroresistant subpopulations after exposure of A. baumannii strains to FDC and its instability. Both A. baumannii and FDC are of great interest for the scientific community, as well as for clinicians; the former represents a major threat to public health due to its resistance to antibiotics, with related costs of prolonged hospitalization, and the latter is a novel, promising cephalosporin currently under the magnifying glass.
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Affiliation(s)
- Stefano Stracquadanio
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Carmelo Bonomo
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Andrea Marino
- Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Dafne Bongiorno
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Grete Francesca Privitera
- Department of Clinical and Experimental Medicine, Bioinformatics Unit, University of Catania, Catania, Italy
| | - Dalida Angela Bivona
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Alessia Mirabile
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Paolo Giuseppe Bonacci
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
| | - Stefania Stefani
- Biomedical and Biotechnological Sciences Department, University of Catania, Catania, Italy
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A pyrF-Based Efficient Genetic Manipulation Platform in Acinetobacter baumannii To Explore the Vital DNA Components of Adaptive Immunity for I-F CRISPR-Cas. Microbiol Spectr 2022; 10:e0195722. [PMID: 36047802 PMCID: PMC9602844 DOI: 10.1128/spectrum.01957-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acinetobacter baumannii is an important pathogenic bacterium with multidrug resistance which causes infections with high mortality rates. In-depth genetic analysis of A. baumannii virulence and drug-resistant genes is highly desirable. In this study, we utilized the conserved pyrF-flanking fragment to rapidly generate uracil auxotrophy hosts with pyrF deleted in model and clinical A. baumannii strains and then introduced the pyrF gene as the selectable and counterselectable marker to establish a series of gene manipulation vectors. For gene deletion with the suicide pyrF-based plasmid, the second-crossover colonies screened with the pyrF/5-fluoroorotic acid (5-FOA) system were obtained more quickly and efficiently than those screened with the sacB/sucrose system. By using the replicative plasmid, the recognized protospacer-adjacent motif (PAM) bias for type I-F CRISPR was experimentally revealed in A. baumannii AYE. Interestingly, interference recognized only the PAM-CC sequence, whereas adaptation priming tolerates 4 PAM sequences. Furthermore, we also performed a rapid and extensive modification of the I-F CRISPR-Cas elements and revealed that the role of double-nucleotide sequence mutants at the end of the repeat could be critical during both CRISPR interference and priming; we also found strong biases for A and demonstrated that adaptation could tolerate certain sequence and size variations of the leader in A. baumannii. In conclusion, this pyrF-based genetic manipulation system was readily applicable and efficient for exploring the genetic characteristics of A. baumannii. IMPORTANCE In this study, we developed the widely applicable and efficient pyrF-based selection and counterselection system in A. baumannii for gene manipulation. In most cases, this pyrF/5-FOA genetic manipulation system was very effective and enabled us to obtain marker-free mutants in a very short period of time. Utilizing this system and the separate mechanism of interference and/or primed adaptation, our experiments revealed some recognition mechanism differences for the key DNA elements of PAM, leader, and repeat in the priming adaptation process of the I-F CRISPR-Cas systems of A. baumannii, which provided some new and original insights for the study of the molecular mechanisms of these processes and laid a foundation for further studies.
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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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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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Hu Y, Zheng J, Zhang J. Natural Transformation in Acinetobacter baumannii W068: A Genetic Analysis Reveals the Involvements of the CRP, XcpV, XcpW, TsaP, and TonB2. Front Microbiol 2022; 12:738034. [PMID: 35126321 PMCID: PMC8811193 DOI: 10.3389/fmicb.2021.738034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 12/14/2021] [Indexed: 01/25/2023] Open
Abstract
Acinetobacter baumannii is a serious threat to public health, and there is increasing attention to the development of antibiotic resistance in this bacterium. Natural transformation is a major horizontal gene transfer mechanism that can lead to antibiotic resistance. To better understand the mechanism of natural transformation in A. baumannii, we selected a clinical isolate that was transformable but had no visible extracellular type IV pili (T4P) filaments and then examined the effects of multiple single-gene knockouts on natural plasmid transformation. Among 33 candidate genes, 28 knockout mutants had severely or completely impaired transformability. Some of these genes had established roles in T4P biogenesis; DNA transfer across the outer membrane, periplasm, or inner membrane; and protection of intracellular single-stranded DNA (ssDNA). Other genes had no previously reported roles in natural transformation of A. baumannii, including competence activator cAMP receptor protein (CRP), a periplasmic protein that may function in T4P assembly (TonB2), a T4P secretin-associated protein (TsaP), and two type II secretion system (T2SS) minor pseudopilus assembly prime complex competent proteins (XcpV and XcpW). The deletion of the T2SS assembly platform protein X had no effect on transformation, and the minor pseudopilins were capable of initiating major pilin assembly. Thus, we speculate that XcpV and XcpW may function in DNA uptake with major pilin assembly, a non-T2SS-dependent mechanism and that a competence pseudopilus similar to T4P constituted the central part of the DNA uptake complex. These results may help guide future research on the alarming increase of antibiotic resistance in this pathogen.
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Affiliation(s)
- Yuan Hu
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Junjie Zheng
- The Fifth Medical Center of Chinese PLA General Hospital, Beijing, China
| | - Jianzhong Zhang
- State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- *Correspondence: Jianzhong Zhang,
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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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14
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Analysis of six tonB gene homologs in Bacteroides fragilis revealed that tonB3 is essential for survival in experimental intestinal colonization and intra-abdominal infection. Infect Immun 2021; 90:e0046921. [PMID: 34662212 DOI: 10.1128/iai.00469-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The opportunistic, anaerobic pathogen and commensal of the human large intestinal tract, Bacteroides fragilis strain 638R, contains six predicted TonB proteins, termed TonB1-6, four ExbBs orthologs, ExbB1-4, and five ExbDs orthologs, ExbD1-5. The inner membrane TonB/ExbB/ExbD complex harvests energy from the proton motive force (Δp) and the TonB C-terminal domain interacts with and transduces energy to outer membrane TonB-dependent transporters (TBDTs). However, TonB's role in activating nearly one hundred TBDTs for nutrient acquisition in B. fragilis during intestinal colonization and extraintestinal infection has not been established. In this study, we show that growth was abolished in the ΔtonB3 mutant when heme, vitamin B12, Fe(III)-ferrichrome, starch, mucin-glycans, or N-linked glycans were used as a substrate for growth in vitro. Genetic complementation of the ΔtonB3 mutant with the tonB3 gene restored growth on these substrates. The ΔtonB1, ΔtonB2, ΔtonB4, ΔtonB5, and ΔtonB6 single mutants did not show a growth defect. This indicates that there was no functional compensation for the lack of TonB3, and it demonstrates that TonB3, alone, drives the TBDTs involved in the transport of essential nutrients. The ΔtonB3 mutant had a severe growth defect in a mouse model of intestinal colonization compared to the parent strain. This intestinal growth defect was enhanced in the ΔtonB3 ΔtonB6 double mutant strain which completely lost its ability to colonize the mouse intestinal tract compared to the parent strain. The ΔtonB1, ΔtonB2, ΔtonB4, and ΔtonB5 mutants did not significantly affect intestinal colonization. Moreover, the survival of the ΔtonB3 mutant strain was completely eradicated in a rat model of intra-abdominal infection. Taken together, these findings show that TonB3 was essential for survival in vivo. The genetic organization of tonB1, tonB2, tonB4, tonB5, and tonB6 gene orthologs indicates that they may interact with periplasmic and nonreceptor outer membrane proteins, but the physiological relevance of this has not been defined. Because anaerobic fermentation metabolism yields a lower Δp than aerobic respiration and B. fragilis has a reduced redox state in its periplasmic space - in contrast to an oxidative environment in aerobes - it remains to be determined if the diverse system of TonB/ExbB/ExbD orthologs encoded by B. fragilis have an increased sensitivity to PMF (relative to aerobic bacteria) to allow for the harvesting of energy under anaerobic conditions.
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15
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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: 58] [Impact Index Per Article: 19.3] [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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16
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Kraut-Cohen J, Shapiro OH, Dror B, Cytryn E. Pectin Induced Colony Expansion of Soil-Derived Flavobacterium Strains. Front Microbiol 2021; 12:651891. [PMID: 33889143 PMCID: PMC8056085 DOI: 10.3389/fmicb.2021.651891] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/22/2021] [Indexed: 11/20/2022] Open
Abstract
The genus Flavobacterium is characterized by the capacity to metabolize complex organic compounds and a unique gliding motility mechanism. Flavobacteria are often abundant in root microbiomes of various plants, but the factors contributing to this high abundance are currently unknown. In this study, we evaluated the effect of various plant-associated poly- and mono-saccharides on colony expansion of two Flavobacterium strains. Both strains were able to spread on pectin and other polysaccharides such as microcrystalline cellulose. However, only pectin (but not pectin monomers), a component of plant cell walls, enhanced colony expansion on solid surfaces in a dose- and substrate-dependent manner. On pectin, flavobacteria exhibited bi-phasic motility, with an initial phase of rapid expansion, followed by growth within the colonized area. Proteomic and gene expression analyses revealed significant induction of carbohydrate metabolism related proteins when flavobacteria were grown on pectin, including selected SusC/D, TonB-dependent glycan transport operons. Our results show a positive correlation between colony expansion and the upregulation of proteins involved in sugar uptake, suggesting an unknown linkage between specific operons encoding for glycan uptake and metabolism and flavobacterial expansion. Furthermore, within the context of flavobacterial-plant interactions, they suggest that pectin may facilitate flavobacterial expansion on plant surfaces in addition to serving as an essential carbon source.
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Affiliation(s)
- Judith Kraut-Cohen
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Orr H Shapiro
- Institute of Postharvest and Food Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
| | - Barak Dror
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel.,Department of Plant Pathology and Microbiology, The R.H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Eddie Cytryn
- Institute of Soil, Water and Environmental Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel
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17
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Chiu CH, Lee YT, Lin YC, Kuo SC, Yang YS, Wang YC, Liu YH, Lin JC, Chang FY, Chen TL. Bacterial membrane vesicles from Acinetobacter baumannii induced by ceftazidime are more virulent than those induced by imipenem. Virulence 2021; 11:145-158. [PMID: 32043433 PMCID: PMC7051140 DOI: 10.1080/21505594.2020.1726593] [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] [Indexed: 11/24/2022] Open
Abstract
Patients with Acinetobacter baumannii bacteremia treated with antipseudomonal cephalosporins showed higher 14-day mortality than patients treated with antipseudomonal carbapenems. We hypothesized that the bacterial membrane vesicles (BMVs) induced by antipseudomonal cephalosporins are more virulent than BMVs induced by antipseudomonal carbapenems. To simulate the clinical condition with inadequate antimicrobial treatment, carbapenem-resistant A. baumannii was treated with ceftazidime (an antipseudomonal cephalosporin) or imipenem (an antipseudomonal carbapenem) at 1/2 the minimum inhibitory concentration. BMVs and BMV-carried lipopolysaccharide were measured by nanoparticle tracking analysis and western blotting, respectively. Cytokine expression in RAW264.7 macrophages or mice serum induced by the BMVs was determined by ELISA, fluorescent bead-based immunoassay or western blotting. The virulence of the BMVs was assessed in mice. Liquid chromatography tandem-mass spectrometry was used to determine the protein contents of the BMVs. We found that ceftazidime induced a higher number of BMVs (CAZ-BMV), which carried more LPS, and induced higher expression levels of iNOS, IL-1β, and IL-6 in macrophages, higher expression of many cytokines in mice, more neutrophil infiltration in lung interstitium, and higher mortality in mice than imipenem-induced BMVs (IMP-BMV). When adjusted to same amount of LPS, CAZ-BMV still led to higher mortality than IMP-BMV. Proteomic analysis revealed different protein contents in CAZ-BMV and IMP-BMV. In conclusion, A. baumannii BMVs induced by ceftazidime are more virulent than BMVs induced by imipenem.
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Affiliation(s)
- Chun-Hsiang Chiu
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Tzu Lee
- Emergency Department, Taipei Veterans General Hospital, Taipei, Taiwan.,School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Chun Lin
- Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.,Department of Graduate Institute of Pathology and Parasitology, National Defense Medical Center, Taipei, Taiwan
| | - Shu-Chen Kuo
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli County, Taiwan
| | - Ya-Sung Yang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yung-Chih Wang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Han Liu
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Jung-Chung Lin
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Feng-Yee Chang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Te-Li Chen
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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18
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Hamidian M, Blasco L, Tillman LN, To J, Tomas M, Myers GSA. Analysis of Complete Genome Sequence of Acinetobacter baumannii Strain ATCC 19606 Reveals Novel Mobile Genetic Elements and Novel Prophage. Microorganisms 2020; 8:E1851. [PMID: 33255319 PMCID: PMC7760358 DOI: 10.3390/microorganisms8121851] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/18/2020] [Accepted: 11/21/2020] [Indexed: 11/16/2022] Open
Abstract
Acinetobacter baumannii isolate ATCC 19606 was recovered in the US prior to 1948. It has been used as a reference and model organism in many studies involving antibiotic resistance and pathogenesis of A. baumannii, while, until recently, a complete genome of this strain was not available. Here, we present an analysis of the complete 3.91-Mbp genome sequence, generated via a combination of short-read sequencing (Illumina) and long-read sequencing (MinION), and show it contains two small cryptic plasmids and a novel complete prophage of size 41.2 kb. We also characterised several regions of the ATCC 19606 genome, leading to the identification of a novel cadmium/mercury transposon, which was named Tn6551. ATCC 19606 is an antibiotic-sensitive strain, but a comparative analysis of all publicly available ST52 strains predicts a resistance to modern antibiotics by the accumulation of antibiotic-resistance genes via plasmids in recent isolates that belong to this sequence type.
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Affiliation(s)
- Mohammad Hamidian
- The iThree Institute, University of Technology Sydney, Ultimo 2007, NSW, Australia; (L.N.T.); (J.T.); (G.S.A.M.)
| | - Lucia Blasco
- Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15495 A Coruña, Spain; (L.B.); (M.T.)
| | - Lauren N. Tillman
- The iThree Institute, University of Technology Sydney, Ultimo 2007, NSW, Australia; (L.N.T.); (J.T.); (G.S.A.M.)
| | - Joyce To
- The iThree Institute, University of Technology Sydney, Ultimo 2007, NSW, Australia; (L.N.T.); (J.T.); (G.S.A.M.)
| | - María Tomas
- Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15495 A Coruña, Spain; (L.B.); (M.T.)
| | - Garry S. A. Myers
- The iThree Institute, University of Technology Sydney, Ultimo 2007, NSW, Australia; (L.N.T.); (J.T.); (G.S.A.M.)
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19
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Proteomic and Systematic Functional Profiling Unveils Citral Targeting Antibiotic Resistance, Antioxidant Defense, and Biofilm-Associated Two-Component Systems of Acinetobacter baumannii To Encumber Biofilm and Virulence Traits. mSystems 2020; 5:5/6/e00986-20. [PMID: 33203690 PMCID: PMC7677002 DOI: 10.1128/msystems.00986-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a nosocomial-infection-causing bacterium and also possesses multidrug resistance to a wide range of conventional antibiotics. The biofilm-forming ability of A. baumannii plays a major role in its resistance and persistence. There is an alarming need for novel treatment strategies to control A. baumannii biofilm-associated issues. The present study demonstrated the strong antibiofilm and antivirulence efficacy of citral against A. baumannii. In addition, proteomic analysis revealed the multitarget potential of citral against A. baumannii. Furthermore, citral treatment enhances the susceptibility of A. baumannii to the host innate immune system and reactive oxygen species (ROS). Cytotoxicity analysis revealed the nonfatal effect of citral on human PBMCs. Therefore, citral could be the safest therapeutic compound and can be taken for further clinical evaluation for the treatment of biofilm-associated infections by A. baumannii. Acinetobacter baumannii has been reported as a multidrug-resistant bacterium due to biofilms and antimicrobial resistance mechanisms. Hence, novel therapeutic strategies are necessary to overcome A. baumannii infections. This study revealed that citral at 200 μg/ml attenuated A. baumannii biofilms by up to 90% without affecting viability. Furthermore, microscopic analyses and in vitro assays confirmed the antibiofilm efficacy of citral. The global effect of citral on A. baumannii was evaluated by proteomic, transcriptional, and in silico approaches. Two-dimensional (2D) gel electrophoresis and matrix-assisted laser desorption ionization–time of flight/time of flight (MALDI-TOF/TOF) analyses were used to assess the effect of citral on the A. baumannii cellular proteome. Quantitative real-time PCR (qPCR) analysis was done to validate the proteomic data and identify the differentially expressed A. baumannii genes. Protein-protein interactions, gene enrichment, and comparative gene network analyses were performed to explore the interactions and functional attributes of differentially expressed proteins of A. baumannii. Global omics-based analyses revealed that citral targeted various mechanisms such as biofilm formation, antibiotic resistance, antioxidant defense, iron acquisition, and type II and type IV secretion systems. The results of antioxidant analyses and antibiotic sensitivity, blood survival, lipase, and hemolysis assays validated the proteomic results. Cytotoxicity analysis showed a nontoxic effect of citral on peripheral blood mononuclear cells (PBMCs). Overall, the current study unveiled that citral has multitarget efficacy to inhibit the biofilm formation and virulence of A. baumannii. IMPORTANCEAcinetobacter baumannii is a nosocomial-infection-causing bacterium and also possesses multidrug resistance to a wide range of conventional antibiotics. The biofilm-forming ability of A. baumannii plays a major role in its resistance and persistence. There is an alarming need for novel treatment strategies to control A. baumannii biofilm-associated issues. The present study demonstrated the strong antibiofilm and antivirulence efficacy of citral against A. baumannii. In addition, proteomic analysis revealed the multitarget potential of citral against A. baumannii. Furthermore, citral treatment enhances the susceptibility of A. baumannii to the host innate immune system and reactive oxygen species (ROS). Cytotoxicity analysis revealed the nonfatal effect of citral on human PBMCs. Therefore, citral could be the safest therapeutic compound and can be taken for further clinical evaluation for the treatment of biofilm-associated infections by A. baumannii.
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20
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Wang Y, Lu J, Engelstädter J, Zhang S, Ding P, Mao L, Yuan Z, Bond PL, Guo J. Non-antibiotic pharmaceuticals enhance the transmission of exogenous antibiotic resistance genes through bacterial transformation. THE ISME JOURNAL 2020; 14:2179-2196. [PMID: 32424247 PMCID: PMC7367833 DOI: 10.1038/s41396-020-0679-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/19/2022]
Abstract
Antibiotic resistance is a serious global threat for public health. Considering the high abundance of cell-free DNA encoding antibiotic resistance genes (ARGs) in both clinical and environmental settings, natural transformation is an important horizontal gene transfer pathway to transmit antibiotic resistance. It is acknowledged that antibiotics are key drivers for disseminating antibiotic resistance, yet the contributions of non-antibiotic pharmaceuticals on transformation of ARGs are overlooked. In this study, we report that some commonly consumed non-antibiotic pharmaceuticals, at clinically and environmentally relevant concentrations, significantly facilitated the spread of antibiotic resistance through the uptake of exogenous ARGs. This included nonsteroidal anti-inflammatories, ibuprofen, naproxen, diclofenac, the lipid-lowering drug, gemfibrozil, and the β-blocker propranolol. Based on the results of flow cytometry, whole-genome RNA sequencing and proteomic analysis, the enhanced transformation of ARGs was affiliated with promoted bacterial competence, enhanced stress levels, over-produced reactive oxygen species and increased cell membrane permeability. In addition, a mathematical model was proposed and calibrated to predict the dynamics of transformation during exposure to non-antibiotic pharmaceuticals. Given the high consumption of non-antibiotic pharmaceuticals, these findings reveal new concerns regarding antibiotic resistance dissemination exacerbated by non-antibiotic pharmaceuticals.
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Affiliation(s)
- Yue Wang
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ji Lu
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Shuai Zhang
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Pengbo Ding
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Likai Mao
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Philip L Bond
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia.
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21
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Colquhoun JM, Rather PN. Insights Into Mechanisms of Biofilm Formation in Acinetobacter baumannii and Implications for Uropathogenesis. Front Cell Infect Microbiol 2020; 10:253. [PMID: 32547965 PMCID: PMC7273844 DOI: 10.3389/fcimb.2020.00253] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 04/30/2020] [Indexed: 01/10/2023] Open
Abstract
Multidrug resistant Acinetobacter baumannii is a serious healthcare threat. In fact, the Center for Disease Control recently reported that carbapenem-resistant A. baumannii is responsible for more than 8,500 infections, 700 deaths, and $281 million in healthcare costs annually in the United States with few, if any, treatment options available, leading to its designation as a pathogen of urgent concern and a priority for novel antimicrobial development. It is hypothesized that biofilms are, at least in part, responsible for the high prevalence of A. baumannii nosocomial and recurrent infections because they frequently contaminate hospital surfaces and patient indwelling devices; therefore, there has been a recent push for mechanistic understanding of biofilm formation, maturation and dispersal. However, most research has focused on A. baumannii pneumonia and bloodstream infections, despite a recent retrospective study showing that 17.1% of A. baumannii isolates compiled from clinical studies over the last two decades were obtained from urinary samples. This highlights that A. baumannii is an underappreciated uropathogen. The following minireview will examine our current understanding of A. baumannii biofilm formation and how this influences urinary tract colonization and pathogenesis.
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Affiliation(s)
- Jennifer M Colquhoun
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, United States
| | - Philip N Rather
- Department of Microbiology and Immunology, Emory University, Atlanta, GA, United States.,Research Service, Atlanta VA Healthcare System, Decatur, GA, United States
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22
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Nguyen LP, Pinto NA, Vu TN, Lee H, Cho YL, Byun JH, D’Souza R, Yong D. In Vitro Activity of a Novel Siderophore-Cephalosporin, GT-1 and Serine-Type β-Lactamase Inhibitor, GT-055, against Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. Panel Strains. Antibiotics (Basel) 2020; 9:antibiotics9050267. [PMID: 32443875 PMCID: PMC7277296 DOI: 10.3390/antibiotics9050267] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/13/2020] [Accepted: 05/19/2020] [Indexed: 11/16/2022] Open
Abstract
This study investigates GT-1 (also known as LCB10-0200), a novel-siderophore cephalosporin, inhibited multidrug-resistant (MDR) Gram-negative pathogen, via a Trojan horse strategy exploiting iron-uptake systems. We investigated GT-1 activity and the role of siderophore uptake systems, and the combination of GT-1 and a non-β-lactam β-lactamase inhibitor (BLI) of diazabicyclooctane, GT-055, (also referred to as LCB18-055) against molecularly characterised resistant Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. isolates. GT-1 and GT-1/GT-055 were tested in vitro against comparators among three different characterised panel strain sets. Bacterial resistome and siderophore uptake systems were characterised to elucidate the genetic basis for GT-1 minimum inhibitory concentrations (MICs). GT-1 exhibited in vitro activity (≤2 μg/mL MICs) against many MDR isolates, including extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing E. coli and K. pneumoniae and oxacillinase (OXA)-producing Acinetobacter spp. GT-1 also inhibited strains with mutated siderophore transporters and porins. Although BLI GT-055 exhibited intrinsic activity (MIC 2-8 μg/mL) against most E. coli and K. pneumoniae isolates, GT-055 enhanced the activity of GT-1 against many GT-1-resistant strains. Compared with CAZ-AVI, GT-1/GT-055 exhibited lower MICs against E. coli and K. pneumoniae isolates. GT-1 demonstrated potent in vitro activity against clinical panel strains of E. coli, K. pneumoniae and Acinetobacter spp. GT-055 enhanced the in vitro activity of GT-1 against many GT-1-resistant strains.
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Affiliation(s)
- Le Phuong Nguyen
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul 03722, Korea
| | - Naina Adren Pinto
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul 03722, Korea
| | - Thao Nguyen Vu
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul 03722, Korea
| | - Hyunsook Lee
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul 03722, Korea
| | | | - Jung-Hyun Byun
- Department of Laboratory Medicine, Gyeongsang National University College of Medicine, Gyeongsang National University Hospital, Jinju 52727, Korea;
| | - Roshan D’Souza
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- J. Craig Venter Institute, Rockville, MD 20850, USA
- Correspondence: (R.D.); (D.Y.); Tel.: +1-301-795-7342 (R.D.); +82-2-2228-2442 (D.Y.); Fax: +82-2-364-1583 (D.Y.)
| | - Dongeun Yong
- Department of Laboratory Medicine and Research Institute of Bacterial Resistance, College of Medicine, Yonsei University, Seoul 03722, Korea; (L.P.N.); (N.A.P.); (T.N.V.); (H.L.)
- Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul 03722, Korea
- Correspondence: (R.D.); (D.Y.); Tel.: +1-301-795-7342 (R.D.); +82-2-2228-2442 (D.Y.); Fax: +82-2-364-1583 (D.Y.)
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The Acinetobacter baumannii Znu System Overcomes Host-Imposed Nutrient Zinc Limitation. Infect Immun 2019; 87:IAI.00746-19. [PMID: 31548324 DOI: 10.1128/iai.00746-19] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen capable of causing a variety of infections, including pneumonia, sepsis, wound, and burn infections. A. baumannii is an increasing threat to public health due to the prevalence of multidrug-resistant strains, leading the World Health Organization to declare A. baumannii a "Priority 1: Critical" pathogen, for which the development of novel antimicrobials is desperately needed. Zinc (Zn) is an essential nutrient that pathogenic bacteria, including A. baumannii, must acquire from their hosts in order to survive. Consequently, vertebrate hosts have defense mechanisms to sequester Zn from invading bacteria through a process known as nutritional immunity. Here, we describe a Zn uptake (Znu) system that enables A. baumannii to overcome this host-imposed Zn limitation. The Znu system consists of an inner membrane ABC transporter and an outer membrane TonB-dependent receptor. Strains of A. baumannii lacking any individual Znu component are unable to grow in Zn-starved conditions, including in the presence of the host nutritional immunity protein calprotectin. The Znu system contributes to Zn-limited growth by aiding directly in the uptake of Zn into A. baumannii cells and is important for pathogenesis in murine models of A. baumannii infection. These results demonstrate that the Znu system allows A. baumannii to subvert host nutritional immunity and acquire Zn during infection.
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New Shuttle Vectors for Real-Time Gene Expression Analysis in Multidrug-Resistant Acinetobacter Species: In Vitro and In Vivo Responses to Environmental Stressors. Appl Environ Microbiol 2019; 85:AEM.01334-19. [PMID: 31324623 DOI: 10.1128/aem.01334-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 07/06/2019] [Indexed: 11/20/2022] Open
Abstract
The Acinetobacter genus includes species of opportunistic pathogens and harmless saprophytes. The type species, Acinetobacter baumannii, is a nosocomial pathogen renowned for being multidrug resistant (MDR). Despite the clinical relevance of infections caused by MDR A. baumannii and a few other Acinetobacter spp., the regulation of their pathogenicity remains elusive due to the scarcity of adequate genetic tools, including vectors for gene expression analysis. Here, we report the generation and testing of a series of Escherichia coli-Acinetobacter promoter-probe vectors suitable for gene expression analysis in Acinetobacter spp. These vectors, named pLPV1Z, pLPV2Z, and pLPV3Z, carry both gentamicin and zeocin resistance markers and contain lux, lacZ, and green fluorescent protein (GFP) reporter systems downstream of an extended polylinker, respectively. The presence of a toxin-antitoxin gene system and the high copy number allow pLPV plasmids to be stably maintained even without antibiotic selection. The pLPV plasmids can easily be introduced by electroporation into MDR A. baumannii belonging to the major international lineages as well as into species of the Acinetobacter calcoaceticus-A. baumannii complex. The pLPV vectors have successfully been employed to study the regulation of stress-responsive A. baumannii promoters, including the DNA damage-inducible uvrABC promoter, the ethanol-inducible adhP and yahK promoters, and the iron-repressible promoter of the acinetobactin siderophore biosynthesis gene basA A lux-tagged A. baumannii ATCC 19606T strain, carrying the iron-responsive pLPV1Z::PbasA promoter fusion, allowed in vivo and ex vivo monitoring of the bacterial burden in the Galleria mellonella infection model.IMPORTANCE The short-term adaptive response to environmental cues greatly contributes to the ecological success of bacteria, and profound alterations in bacterial gene expression occur in response to physical, chemical, and nutritional stresses. Bacteria belonging to the Acinetobacter genus are ubiquitous inhabitants of soil and water though some species, such as Acinetobacter baumannii, are pathogenic and cause serious concern due to antibiotic resistance. Understanding A. baumannii pathobiology requires adequate genetic tools for gene expression analysis, and to this end we developed user-friendly shuttle vectors to probe the transcriptional responses to different environmental stresses. Vectors were constructed to overcome the problem of antibiotic selection in multidrug-resistant strains and were equipped with suitable reporter systems to facilitate signal detection. By means of these vectors, the transcriptional response of A. baumannii to DNA damage, ethanol exposure, and iron starvation was investigated both in vitro and in vivo, providing insights into A. baumannii adaptation during stress and infection.
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Pires S, Parker D. Innate Immune Responses to Acinetobacter baumannii in the Airway. J Interferon Cytokine Res 2019; 39:441-449. [PMID: 31013462 DOI: 10.1089/jir.2019.0008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acinetobacter baumannii is an emerging opportunistic pathogen that has risen to become a serious global threat, prevalent in health care settings and the community, which results in high morbidity and mortality rates. Its alarming expansion of antibiotic resistance is one of the most problematic traits of A. baumannii and as so, this bacterium has been classified as a serious threat and high priority target by the CDC. The most common types of infections induced by this pathogen include pneumonia (both hospital and community acquired), bacteremia, skin and soft tissue, urinary tract infections, endocarditis, and meningitis. Nosocomial pneumonia is the most prevalent of these. This review summarizes the current state of the signaling and innate immune components activated in response to A. baumannii infection in the airway.
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Affiliation(s)
- Sílvia Pires
- Department of Pathology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Dane Parker
- Department of Pathology and Laboratory Medicine, Center for Immunity and Inflammation, Rutgers New Jersey Medical School, Newark, New Jersey
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Contribution of Active Iron Uptake to Acinetobacter baumannii Pathogenicity. Infect Immun 2019; 87:IAI.00755-18. [PMID: 30718286 DOI: 10.1128/iai.00755-18] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/25/2019] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen. Mechanisms that allow A. baumannii to cause human infection are still poorly understood. Iron is an essential nutrient for bacterial growth in vivo, and the multiplicity of iron uptake systems in A. baumannii suggests that iron acquisition contributes to the ability of A. baumannii to cause infection. In Gram-negative bacteria, active transport of ferrisiderophores and heme relies on the conserved TonB-ExbB-ExbD energy-transducing complex, while active uptake of ferrous iron is mediated by the Feo system. The A. baumannii genome invariably contains three tonB genes (tonB1, tonB2, and tonB3), whose role in iron uptake is poorly understood. Here, we generated A. baumannii mutants with knockout mutations in the feo and/or tonB gene. We report that tonB3 is essential for A. baumannii growth under iron-limiting conditions, whereas tonB1, tonB2, and feoB appear to be dispensable for ferric iron uptake. tonB3 deletion resulted in reduced intracellular iron content despite siderophore overproduction, supporting a key role of TonB3 in iron uptake. In contrast to the case for tonB1 and tonB2, the promoters of tonB3 and feo contain functional Fur boxes and are upregulated in iron-poor media. Both TonB3 and Feo systems are required for growth in complement-free human serum and contribute to resistance to the bactericidal activity of normal human serum, but only TonB3 appears to be essential for virulence in insect and mouse models of infection. Our findings highlight a central role of the TonB3 system for A. baumannii pathogenicity. Hence, TonB3 represents a promising target for novel antibacterial therapies and for the generation of attenuated vaccine strains.
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Traglia G, Chiem K, Quinn B, Fernandez JS, Montaña S, Almuzara M, Mussi MA, Tolmasky ME, Iriarte A, Centrón D, Ramírez MS. Genome sequence analysis of an extensively drug-resistant Acinetobacter baumannii indigo-pigmented strain depicts evidence of increase genome plasticity. Sci Rep 2018; 8:16961. [PMID: 30446709 PMCID: PMC6240043 DOI: 10.1038/s41598-018-35377-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 10/29/2018] [Indexed: 01/02/2023] Open
Abstract
Acinetobacter baumannii is a multidrug resistant nosocomial pathogen that shows an outstanding ability to undergo genetic exchange, thereby acquiring different traits that contribute to its success. In this work, we identified genetic features of an indigo-pigmented A. baumannii strain (Ab33405) that belongs to the clonal complex CC113B/CC79P. Ab33405 possesses a high number of genes coding for antibiotic resistance and virulence factors that may contribute to its survival, not only in the human host, but also in the hospital environment. Thirteen genes conferring resistance to different antibiotic families (trimethoprim, florfenicol, β-lactams, aminoglycosides and sulfonamide) as well as the adeIJK genes and the capsule locus (KL) and outer core locus (OCL) were identified. Ab33405 includes 250 unique genes and a significant number of elements associated with Horizontal Gene Transfer, such as insertion sequences and transposons, genomic islands and prophage sequences. Also, the indigo-pigmented uncommon phenotype that could be associated with the monooxygenase or dioxygenase enzyme coded for by the iacA gene within the iac cluster was probably conferred by insertion of a 18-kb DNA fragment into the iacG gene belonging to this cluster. The Ab33405 genome includes all type VI secretion system genes and killing assays showed the ability of Ab33045 to kill Escherichia coli. In addition, Ab33405 can modulate susceptibility antibiotics when exposed to blue light.
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Affiliation(s)
- German Traglia
- Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Kevin Chiem
- Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, USA
| | - Brettni Quinn
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, USA
| | - Jennifer S Fernandez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, USA
| | - Sabrina Montaña
- Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marisa Almuzara
- Laboratorio de Bacteriología, Hospital Interzonal de Agudos Eva Perón, San Martín Buenos Aires, Argentina
| | - María Alejandra Mussi
- Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI- CONICET), Rosario, Argentina
| | - Marcelo E Tolmasky
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, USA
| | - Andres Iriarte
- Laboratorio de Biología Computacional, Dpto. de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Daniela Centrón
- Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, California State University Fullerton, Fullerton, CA, USA.
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Quinn B, Rodman N, Jara E, Fernandez JS, Martinez J, Traglia GM, Montaña S, Cantera V, Place K, Bonomo RA, Iriarte A, Ramírez MS. Human serum albumin alters specific genes that can play a role in survival and persistence in Acinetobacter baumannii. Sci Rep 2018; 8:14741. [PMID: 30282985 PMCID: PMC6170387 DOI: 10.1038/s41598-018-33072-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 09/21/2018] [Indexed: 01/13/2023] Open
Abstract
In the past few decades Acinetobacter baumannii has emerged as a notorious nosocomial pathogen because of its ability to acquire genetic material and persist in extreme environments. Recently, human serum albumin (HSA) was shown to significantly increase natural transformation frequency in A. baumannii. This observation led us to perform transcriptomic analysis of strain A118 under HSA induction to identify genes that are altered by HSA. Our results revealed the statistically significant differential expression of 296 protein-coding genes, including those associated with motility, biofilm formation, metabolism, efflux pumps, capsule synthesis, and transcriptional regulation. Phenotypic analysis of these traits showed an increase in surface-associated motility, a decrease in biofilm formation, reduced activity of a citric acid cycle associated enzyme, and increased survival associated with zinc availability. Furthermore, the expression of genes known to play a role in pathogenicity and antibiotic resistance were altered. These genes included those associated with RND-type efflux pumps, the type VI secretion system, iron acquisition/metabolism, and ß-lactam resistance. Together, these results illustrate how human products, in particular HSA, may play a significant role in both survival and persistence of A. baumannii.
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Affiliation(s)
- Brettni Quinn
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Nyah Rodman
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Eugenio Jara
- Área Genética, Facultad de Veterinaria, Universidad de la República, Montevideo, Uruguay
| | - Jennifer S Fernandez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Jasmine Martinez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - German M Traglia
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
| | - Sabrina Montaña
- Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos, Aires, Argentina
| | - Virginia Cantera
- Laboratorio de Biología Computacional, Dpto. de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR, Montevideo, Uruguay
| | - Kori Place
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA
| | - Robert A Bonomo
- Medical Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA.,Departments of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry, Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.,CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - Andres Iriarte
- Laboratorio de Biología Computacional, Dpto. de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR, Montevideo, Uruguay
| | - María Soledad Ramírez
- Center for Applied Biotechnology Studies, Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, California, USA.
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29
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Uppuluri P, Lin L, Alqarihi A, Luo G, Youssef EG, Alkhazraji S, Yount NY, Ibrahim BA, Bolaris MA, Edwards JE, Swidergall M, Filler SG, Yeaman MR, Ibrahim AS. The Hyr1 protein from the fungus Candida albicans is a cross kingdom immunotherapeutic target for Acinetobacter bacterial infection. PLoS Pathog 2018; 14:e1007056. [PMID: 29746596 PMCID: PMC5963808 DOI: 10.1371/journal.ppat.1007056] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/22/2018] [Accepted: 04/26/2018] [Indexed: 11/21/2022] Open
Abstract
Different pathogens share similar medical settings and rely on similar virulence strategies to cause infections. We have previously applied 3-D computational modeling and bioinformatics to discover novel antigens that target more than one human pathogen. Active and passive immunization with the recombinant N-terminus of Candida albicans Hyr1 (rHyr1p-N) protect mice against lethal candidemia. Here we determine that Hyr1p shares homology with cell surface proteins of the multidrug resistant Gram negative bacterium, Acinetobacter baumannii including hemagglutinin (FhaB) and outer membrane protein A (OmpA). The A. baumannii OmpA binds to C. albicans Hyr1p, leading to a mixed species biofilm. Deletion of HYR1, or blocking of Hyr1p using polyclonal antibodies, significantly reduce A. baumannii binding to C. albicans hyphae. Furthermore, active vaccination with rHyr1p-N or passive immunization with polyclonal antibodies raised against specific peptide motifs of rHyr1p-N markedly improve survival of diabetic or neutropenic mice infected with A. baumannii bacteremia or pneumonia. Antibody raised against one particular peptide of the rHyr1p-N sequence (peptide 5) confers majority of the protection through blocking A. baumannii invasion of host cells and inducing death of the bacterium by a putative iron starvation mechanism. Anti-Hyr1 peptide 5 antibodies also mitigate A. baumannii /C. albicans mixed biofilm formation in vitro. Consistent with our bioinformatic analysis and structural modeling of Hyr1p, anti-Hyr1p peptide 5 antibodies bound to A. baumannii FhaB, OmpA, and an outer membrane siderophore binding protein. Our studies highlight the concept of cross-kingdom vaccine protection against high priority human pathogens such as A. baumannii and C. albicans that share similar ecological niches in immunocompromised patients.
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Affiliation(s)
- Priya Uppuluri
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Lin Lin
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Abdullah Alqarihi
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Guanpingsheng Luo
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Eman G. Youssef
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Biotechnology and Life Sciences, Faculty of Postgraduate Studies for Advanced Sciences (PSAS), Beni-Suef University, Beni-Suef, Egypt
| | - Sondus Alkhazraji
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Nannette Y. Yount
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Belal A. Ibrahim
- Portola High School, Irvine, California, United States of America
| | - Michael Anthony Bolaris
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - John E. Edwards
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Marc Swidergall
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
| | - Scott G. Filler
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Michael R. Yeaman
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
| | - Ashraf S. Ibrahim
- Department of Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California at Los Angeles (UCLA) Medical Center, Torrance, California, United States of America
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
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30
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An in silico structural and physicochemical characterization of TonB-dependent copper receptor in A. baumannii. Microb Pathog 2018. [DOI: 10.1016/j.micpath.2018.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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31
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Abdollahi S, Rasooli I, Mousavi Gargari SL. The role of TonB-dependent copper receptor in virulence of Acinetobacter baumannii. INFECTION GENETICS AND EVOLUTION 2018; 60:181-190. [PMID: 29505819 DOI: 10.1016/j.meegid.2018.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 02/11/2018] [Accepted: 03/01/2018] [Indexed: 12/15/2022]
Abstract
Acinetobacter baumannii is an opportunistic gram negative pathogen that can adhere to different surfaces and cause different nosocomial infections. To investigate the role of TonB-dependent copper receptor, an outer membrane protein, in virulence of A. baumannii, we deleted this receptor from A. baumannii chromosome. There was a significant decrease in biofilm formation by copper receptor deficient mutant strain. Similarly, the adherence to human epithelial cell and the hydrophobicity were declined. The survival rate of the mutant strain in human sera was reduced while no change was observed in motility of strains. In murine pneumonia model, the bacterial lethal dose 0 (LD0), LD50 and LD100 were increased for mutant strain. Moreover, in vivo and in vitro experiments revealed changes in growth rate and dissemination of mutant strain; so that the bacterial load of the mutant was significantly reduced in the spleen and lung. The findings suggest a critical role for TonB-dependent copper receptor in virulence of A. baumannii.
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Affiliation(s)
| | - Iraj Rasooli
- Department of Biology, Shahed University, Tehran, Iran; Molecular Microbiology Research Center, Shahed University, Tehran, Iran.
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32
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Abdelhamed H, Lawrence ML, Karsi A. The Role of TonB Gene in Edwardsiella ictaluri Virulence. Front Physiol 2017; 8:1066. [PMID: 29326601 PMCID: PMC5741614 DOI: 10.3389/fphys.2017.01066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/04/2017] [Indexed: 11/13/2022] Open
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen that causes enteric septicemia in catfish (ESC). Stress factors including poor water quality, poor diet, rough handling, overcrowding, and water temperature fluctuations increase fish susceptibility to ESC. The TonB energy transducing system (TonB-ExbB-ExbD) and TonB-dependent transporters of Gram-negative bacteria support active transport of scarce resources including iron, an essential micronutrient for bacterial virulence. Deletion of the tonB gene attenuates virulence in several pathogenic bacteria. In the current study, the role of TonB (NT01EI_RS07425) in iron acquisition and E. ictaluri virulence were investigated. To accomplish this, the E. ictaluri tonB gene was in-frame deleted. Growth kinetics, iron utilization, and virulence of the EiΔtonB mutant were determined. Loss of TonB caused a significant reduction in bacterial growth in iron-depleted medium (p > 0.05). The EiΔtonB mutant grew similarly to wild-type E. ictaluri when ferric iron was added to the iron-depleted medium. The EiΔtonB mutant was significantly attenuated in catfish compared with the parent strain (21.69 vs. 46.91% mortality). Catfish surviving infection with EiΔtonB had significant protection against ESC compared with naïve fish (100 vs. 40.47% survival). These findings indicate that TonB participates in pathogenesis of ESC and is an important E. ictaluri virulence factor.
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Affiliation(s)
- Hossam Abdelhamed
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Mark L Lawrence
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Attila Karsi
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges. Clin Microbiol Rev 2017; 30:409-447. [PMID: 27974412 DOI: 10.1128/cmr.00058-16] [Citation(s) in RCA: 634] [Impact Index Per Article: 90.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)-Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed.
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Lean SS, Yeo CC. Small, Enigmatic Plasmids of the Nosocomial Pathogen, Acinetobacter baumannii: Good, Bad, Who Knows? Front Microbiol 2017; 8:1547. [PMID: 28861061 PMCID: PMC5559437 DOI: 10.3389/fmicb.2017.01547] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has become a serious healthcare concern within a span of two decades due to its ability to rapidly acquire resistance to all classes of antimicrobial compounds. One of the key features of the A. baumannii genome is an open pan genome with a plethora of plasmids, transposons, integrons, and genomic islands, all of which play important roles in the evolution and success of this clinical pathogen, particularly in the acquisition of multidrug resistance determinants. An interesting genetic feature seen in majority of A. baumannii genomes analyzed is the presence of small plasmids that usually ranged from 2 to 10 kb in size, some of which harbor antibiotic resistance genes and homologs of plasmid mobilization genes. These plasmids are often overlooked when compared to their larger, conjugative counterparts that harbor multiple antibiotic resistance genes and transposable elements. In this mini-review, we will examine our current knowledge of these small A. baumannii plasmids and look into their genetic diversity and phylogenetic relationships. Some of these plasmids, such as the Rep-3 superfamily group and the pRAY-type, which has no recognizable replicase genes, are quite widespread among diverse A. baumannii clinical isolates worldwide, hinting at their usefulness to the lifestyle of this pathogen. Other small plasmids especially those from the Rep-1 superfamily are truly enigmatic, encoding only hypothetical proteins of unknown function, leading to the question of whether these small plasmids are “good” or “bad” to their host A. baumannii.
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Affiliation(s)
- Soo Sum Lean
- Saw Swee Hock School of Public Health, National University of SingaporeSingapore, Singapore
| | - Chew Chieng Yeo
- Faculty of Medicine, Biomedical Research Centre, Universiti Sultan Zainal AbidinKuala Terengganu, Malaysia
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Rumbo-Feal S, Pérez A, Ramelot TA, Álvarez-Fraga L, Vallejo JA, Beceiro A, Ohneck EJ, Arivett BA, Merino M, Fiester SE, Kennedy MA, Actis LA, Bou G, Poza M. Contribution of the A. baumannii A1S_0114 Gene to the Interaction with Eukaryotic Cells and Virulence. Front Cell Infect Microbiol 2017; 7:108. [PMID: 28421168 PMCID: PMC5376624 DOI: 10.3389/fcimb.2017.00108] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 03/17/2017] [Indexed: 11/29/2022] Open
Abstract
Genetic and functional studies showed that some components of the Acinetobacter baumannii ATCC 17978 A1S_0112-A1S_0119 gene cluster are critical for biofilm biogenesis and surface motility. Recently, our group has shown that the A1S_0114 gene was involved in biofilm formation, a process related with pathogenesis. Confirming our previous results, microscopy images revealed that the ATCC 17978 Δ0114 derivative lacking this gene was unable to form a mature biofilm structure. Therefore, other bacterial phenotypes were analyzed to determine the role of this gene in the pathogenicity of A. baumannii ATCC 17978. The interaction of the ATCC 17978 parental strain and the Δ0114 mutant with A549 human alveolar epithelial cells was quantified revealing that the A1S_0114 gene was necessary for proper attachment to A549 cells. This dependency correlates with the negative effect of the A1S_0114 deletion on the expression of genes coding for surface proteins and pili-assembly systems, which are known to play a role in adhesion. Three different experimental animal models, including vertebrate and invertebrate hosts, confirmed the role of the A1S_0114 gene in virulence. All of the experimental infection assays indicated that the virulence of the ATCC 17978 was significantly reduced when this gene was inactivated. Finally, we discovered that the A1S_0114 gene was involved in the production of a small lipopeptide-like compound herein referred to as acinetin 505 (Ac-505). Ac-505 was isolated from ATCC 17978 spent media and its chemical structure was interpreted by mass spectrometry. Overall, our observations provide novel information on the role of the A1S_0114 gene in A. baumannii's pathobiology and lay the foundation for future work to determine the mechanisms by which Ac-505, or possibly an Ac-505 precursor, could execute critical functions as a secondary metabolite.
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Affiliation(s)
- Soraya Rumbo-Feal
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Astrid Pérez
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain.,Departamento de Microbiología y Parasitología, Universidad de Santiago de CompostelaSantiago de Compostela, Spain.,Department of Microbiology, Miami UniversityOxford, OH, USA
| | - Theresa A Ramelot
- Department of Chemistry and Biochemistry, Miami UniversityOxford, OH, USA
| | - Laura Álvarez-Fraga
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Juan A Vallejo
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Alejandro Beceiro
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Emily J Ohneck
- Department of Microbiology, Miami UniversityOxford, OH, USA
| | | | - María Merino
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | | | - Michael A Kennedy
- Department of Chemistry and Biochemistry, Miami UniversityOxford, OH, USA
| | - Luis A Actis
- Department of Microbiology, Miami UniversityOxford, OH, USA
| | - Germán Bou
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
| | - Margarita Poza
- Departamento de Microbiología, Instituto de Investigación Biomédica, Complejo Hospitalario Universitario (CHUAC), Universidad de A Coruña (UDC)A Coruña, Spain
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Structure and Function of the PiuA and PirA Siderophore-Drug Receptors from Pseudomonas aeruginosa and Acinetobacter baumannii. Antimicrob Agents Chemother 2017; 61:AAC.02531-16. [PMID: 28137795 DOI: 10.1128/aac.02531-16] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/27/2017] [Indexed: 01/06/2023] Open
Abstract
The outer membrane of Gram-negative bacteria presents an efficient barrier to the permeation of antimicrobial molecules. One strategy pursued to circumvent this obstacle is to hijack transport systems for essential nutrients, such as iron. BAL30072 and MC-1 are two monobactams conjugated to a dihydroxypyridone siderophore that are active against Pseudomonas aeruginosa and Acinetobacter baumannii Here, we investigated the mechanism of action of these molecules in A. baumannii We identified two novel TonB-dependent receptors, termed Ab-PiuA and Ab-PirA, that are required for the antimicrobial activity of both agents. Deletion of either piuA or pirA in A. baumannii resulted in 4- to 8-fold-decreased susceptibility, while their overexpression in the heterologous host P. aeruginosa increased susceptibility to the two siderophore-drug conjugates by 4- to 32-fold. The crystal structures of PiuA and PirA from A. baumannii and their orthologues from P. aeruginosa were determined. The structures revealed similar architectures; however, structural differences between PirA and PiuA point to potential differences between their cognate siderophore ligands. Spontaneous mutants, selected upon exposure to BAL30072, harbored frameshift mutations in either the ExbD3 or the TonB3 protein of A. baumannii, forming the cytoplasmic-membrane complex providing the energy for the siderophore translocation process. The results of this study provide insight for the rational design of novel siderophore-drug conjugates against problematic Gram-negative pathogens.
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A medically relevant capsular polysaccharide in Acinetobacter baumannii is a potential vaccine candidate. Vaccine 2017; 35:1440-1447. [DOI: 10.1016/j.vaccine.2017.01.060] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/19/2017] [Accepted: 01/20/2017] [Indexed: 11/20/2022]
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Xu J, Zhang L, Hou J, Wang X, Liu H, Zheng D, Liang R. iTRAQ-based quantitative proteomic analysis of the global response to 17β-estradiol in estrogen-degradation strain Pseudomonas putida SJTE-1. Sci Rep 2017; 7:41682. [PMID: 28155874 PMCID: PMC5290480 DOI: 10.1038/srep41682] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 12/23/2016] [Indexed: 11/28/2022] Open
Abstract
Microorganism degradation is efficient to remove the steroid hormones like 17β-estradiol (E2); but their degradation mechanism and metabolic network to these chemicals are still not very clear. Here the global responses of the estrogen-degradation strain Pseudomonas putida SJTE-1 to 17β-estradiol and glucose were analyzed and compared using the iTRAQ (isobaric tags for relative and absolute quantization) strategy combined with LC-MS/MS (liquid chromatography-tandem mass spectrometry). 78 proteins were identified with significant changes in expression; 45 proteins and 33 proteins were up-regulated and down-regulated, respectively. These proteins were mainly involved in the processes of stress response, energy metabolism, transportation, chemotaxis and cell motility, and carbon metabolism, considered probably responding to 17β-estradiol and playing a role in its metabolism. The up-regulated proteins in electron transfer, energy generation and transport systems were thought crucial for efficient uptake, translocation and transformation of 17β-estradiol. The over-expression of carbon metabolism proteins indicated cells may activate related pathway members to utilize 17β-estradiol. Meanwhile, proteins functioning in glucose capture and metabolism were mostly down-regulated. These findings provide important clues to reveal the 17β-estradiol degradation mechanism in P. putida and promote its bioremediation applications.
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Affiliation(s)
- Jing Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lei Zhang
- School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jingli Hou
- Instrumental Analysis Center of Shanghai Jiaotong University, 800 Dong-Chuan Road, Shanghai 200240, China
| | - Xiuli Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Huan Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Daning Zheng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Rubing Liang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
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Kröger C, Kary SC, Schauer K, Cameron ADS. Genetic Regulation of Virulence and Antibiotic Resistance in Acinetobacter baumannii. Genes (Basel) 2016; 8:genes8010012. [PMID: 28036056 PMCID: PMC5295007 DOI: 10.3390/genes8010012] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/18/2016] [Accepted: 12/20/2016] [Indexed: 01/14/2023] Open
Abstract
Multidrug resistant microorganisms are forecast to become the single biggest challenge to medical care in the 21st century. Over the last decades, members of the genus Acinetobacter have emerged as bacterial opportunistic pathogens, in particular as challenging nosocomial pathogens because of the rapid evolution of antimicrobial resistances. Although we lack fundamental biological insight into virulence mechanisms, an increasing number of researchers are working to identify virulence factors and to study antibiotic resistance. Here, we review current knowledge regarding the regulation of virulence genes and antibiotic resistance in Acinetobacter baumannii. A survey of the two-component systems AdeRS, BaeSR, GacSA and PmrAB explains how each contributes to antibiotic resistance and virulence gene expression, while BfmRS regulates cell envelope structures important for pathogen persistence. A. baumannii uses the transcription factors Fur and Zur to sense iron or zinc depletion and upregulate genes for metal scavenging as a critical survival tool in an animal host. Quorum sensing, nucleoid-associated proteins, and non-classical transcription factors such as AtfA and small regulatory RNAs are discussed in the context of virulence and antibiotic resistance.
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Affiliation(s)
- Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
| | - Stefani C Kary
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
| | - Kristina Schauer
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim 85764, Germany.
| | - Andrew D S Cameron
- Department of Biology, University of Regina, Regina, SK S4S 042, Canada.
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Pérez A, Merino M, Rumbo-Feal S, Álvarez-Fraga L, Vallejo JA, Beceiro A, Ohneck EJ, Mateos J, Fernández-Puente P, Actis LA, Poza M, Bou G. The FhaB/FhaC two-partner secretion system is involved in adhesion of Acinetobacter baumannii AbH12O-A2 strain. Virulence 2016; 8:959-974. [PMID: 27858524 DOI: 10.1080/21505594.2016.1262313] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii is a hospital-acquired pathogen that shows an extraordinary capacity to stay in the hospital environment. Adherence of the bacteria to eukaryotic cells or to abiotic surfaces is the first step for establishing an infection. The A. baumannii strain AbH12O-A2 showed an exceptional ability to adhere to A549 epithelial cells. The AbFhaB/FhaC 2-partner secretion (TPS) system involved in adhesion was discovered after the screening of the recently determined A. baumannii AbH12O-A2 strain genome (CP009534.1). The AbFhaB is a large exoprotein which transport to the bacterial surface is mediated by the AbFhaC protein. In the present study, the role of this TPS system in the AbH12O-A2 adherence phenotype was investigated. The functional inactivation of this 2-partner secretion system was addressed by analyzing the outer membrane vesicles (OMV) proteomic profile from the wild-type strain and its derivative mutant AbH12O-A2ΔfhaC demonstrating that AbFhaB is no longer detected in the absence of AbFhaC. Scanning electron microscopy (SEM) and adhesion experiments demonstrated that inactivation of the AbFhaB/FhaC system significantly decreases bacterial attachment to A549 alveolar epithelial cells. Moreover, it has been demonstrated that this 2-partner secretion system is involved in fibronectin-mediated adherence of the A. baumannii AbH12O-A2 isolate. Finally, we report that the AbFhaB/FhaC system is involved in virulence when tested using invertebrate and vertebrate hosts. These data suggest the potential role that this AbFhaB/FhaC secretion system could play in the pathobiology of A. baumannii.
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Affiliation(s)
- A Pérez
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain.,b Departamento de Microbiología y Parasitología , Universidad de Santiago de Compostela (USC) , Santiago de Compostela , Spain.,c Department of Microbiology , Miami University , Oxford , OH , USA
| | - M Merino
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - S Rumbo-Feal
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - L Álvarez-Fraga
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - J A Vallejo
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - A Beceiro
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - E J Ohneck
- c Department of Microbiology , Miami University , Oxford , OH , USA
| | - J Mateos
- d Grupo de Proteómica-ProteoRed/Plataforma PBR2-ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complejo Hospitalario Universitario de A Coruña (CHUAC), Universidade da Coruña (UDC) , A Coruña , Spain.,e Marine Research Institute, Consejo Superior de Investigaciones Científicas (CSIC) , Vigo , Spain
| | - P Fernández-Puente
- d Grupo de Proteómica-ProteoRed/Plataforma PBR2-ISCIII, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complejo Hospitalario Universitario de A Coruña (CHUAC), Universidade da Coruña (UDC) , A Coruña , Spain
| | - L A Actis
- c Department of Microbiology , Miami University , Oxford , OH , USA
| | - M Poza
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
| | - G Bou
- a Departamento de Microbiología , Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario (CHUAC), Universidad da Coruña (UDC) , A Coruña , Spain
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41
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Rumbo C, Vallejo JA, Cabral MP, Martínez-Guitián M, Pérez A, Beceiro A, Bou G. Assessment of antivirulence activity of several d-amino acids against Acinetobacter baumannii and Pseudomonas aeruginosa. J Antimicrob Chemother 2016; 71:3473-3481. [PMID: 27605598 DOI: 10.1093/jac/dkw342] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 07/11/2016] [Accepted: 07/25/2016] [Indexed: 12/27/2022] Open
Abstract
OBJECTIVES Biofilm formation and bacterial adherence are important requirements for persistence, multidrug resistance and infection. The d-amino acids play a role as modulators of bacterial growth and persistence, though their ability to inhibit biofilms is much debated. In this study, we analysed the effects of 18 different d-amino acids on the pathogens Acinetobacter baumannii and Pseudomonas aeruginosa. METHODS In vitro assays were carried out to analyse the effect of d-amino acids on bacterial growth, biofilm formation/disassembly, capacity to attach to eukaryotic cells and cellular death. In addition, in vivo assays were performed in mice, using experimental models of sepsis and pneumonia. RESULTS Biofilm formation was inhibited in A. baumannii by d-His, d-Cys and d-Trp (35%-86%) at 2 mM and in P. aeruginosa by d-Cys, d-Trp and d-Tyr (10%-30%) at 4 mM. Attachment to the A549 human alveolar cells was reduced in A. baumannii by d-Cys, d-His, d-Met, d-Val and d-Ser, and in P. aeruginosa by d-Arg and d-Trp. Growth was inhibited in A. baumannii by d-Cys and d-Trp, and in P. aeruginosa by d-Trp. In virulence assays, incubation of alveolar cells infected with P. aeruginosa with d-Cys, d-Trp and d-Arg reduced cell death (56%-45%). However, no significant effect of d-amino acids was observed in vivo. CONCLUSIONS Some d-amino acids can inhibit bacterial growth, biofilm formation and adherence to eukaryotic cells in A. baumannii and P. aeruginosa, and showed a protective effect against infection of alveolar cells with P. aeruginosa. Despite the fact that some considerable protection was observed in mice, survival differences between treated and control groups were not statistically significant.
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Affiliation(s)
- C Rumbo
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - J A Vallejo
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - M P Cabral
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - M Martínez-Guitián
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - A Pérez
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - A Beceiro
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
| | - G Bou
- Servicio de Microbiología-Instituto de Investigación Biomédica (INIBIC), Complejo Hospitalario Universitario A Coruña (CHUAC) As Xubias, 15006 A Coruña, Spain
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Montaña S, Schramm STJ, Traglia GM, Chiem K, Parmeciano Di Noto G, Almuzara M, Barberis C, Vay C, Quiroga C, Tolmasky ME, Iriarte A, Ramírez MS. The Genetic Analysis of an Acinetobacter johnsonii Clinical Strain Evidenced the Presence of Horizontal Genetic Transfer. PLoS One 2016; 11:e0161528. [PMID: 27548264 PMCID: PMC4993456 DOI: 10.1371/journal.pone.0161528] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/08/2016] [Indexed: 02/08/2023] Open
Abstract
Acinetobacter johnsonii rarely causes human infections. While most A. johnsonii isolates are susceptible to virtually all antibiotics, strains harboring a variety of β-lactamases have recently been described. An A. johnsonii Aj2199 clinical strain recovered from a hospital in Buenos Aires produces PER-2 and OXA-58. We decided to delve into its genome by obtaining the whole genome sequence of the Aj2199 strain. Genome comparison studies on Aj2199 revealed 240 unique genes and a close relation to strain WJ10621, isolated from the urine of a patient in China. Genomic analysis showed evidence of horizontal genetic transfer (HGT) events. Forty-five insertion sequences and two intact prophages were found in addition to several resistance determinants such as blaPER-2, blaOXA-58, blaTEM-1, strA, strB, ereA, sul1, aacC2 and a new variant of blaOXA-211, called blaOXA-498. In particular, blaPER-2 and blaTEM-1 are present within the typical contexts previously described in the Enterobacteriaceae family. These results suggest that A. johnsonii actively acquires exogenous DNA from other bacterial species and concomitantly becomes a reservoir of resistance genes.
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Affiliation(s)
- Sabrina Montaña
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Sareda T. J. Schramm
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States of America
| | - German Matías Traglia
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Kevin Chiem
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States of America
| | - Gisela Parmeciano Di Noto
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Marisa Almuzara
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
| | - Claudia Barberis
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
| | - Carlos Vay
- Laboratorio de Bacteriología Clínica, Departamento de Bioquímica Clínica, Hospital de Clínicas José de San Martín, Facultad de Farmacia y Bioquímica, Buenos Aires, Argentina
| | - Cecilia Quiroga
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
| | - Marcelo E. Tolmasky
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States of America
| | - Andrés Iriarte
- Departamento de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR, Montevideo, Uruguay
| | - María Soledad Ramírez
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Buenos Aires, Argentina
- Department of Biological Science, California State University Fullerton, Fullerton, CA, United States of America
- * E-mail:
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In vivo validation of the immunogenicity of recombinant Baumannii Acinetobactin Utilization A protein (rBauA). Microb Pathog 2016; 98:77-81. [PMID: 27374893 DOI: 10.1016/j.micpath.2016.06.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 06/27/2016] [Accepted: 06/28/2016] [Indexed: 11/20/2022]
Abstract
Acinetobacter baumannii has become a tremendous challenge to modern healthcare as an antimicrobial resistant. Replication and persistence of A. baumannii within eukaryotes is based on iron acquisition functions including siderophore biosynthesis. Iron transport into the cytosol is mediated by specific membrane receptors which recognize the iron-siderophore complexes. Expression of this acinetobactin mediated Iron uptake system is vital for intracellular growth of A. baumannii. Baumannii acinetobactin utilization (BauA), is an outer membrane protein, acting out the siderophore-ferric complex receptor. This study was aimed at analysis of immunogenicity and specificity of BauA. The genomic bauA was amplified via PCR method and after digestion, bauA was ligated into pET28a. The recombinant gene was expressed in Escherichia coli BL21(DE3) and the product was analyzed by SDS-PAGE and purified by Ni-NTA affinity chromatography method. The recombinant BauA (rBauA) was confirmed by western blot analysis using anti-His antibodies and its immunogenicity was assessed by injecting the rBauA to BALB/c mice. Antibodies produced therein could effectively recognize and bind rBauA. The immunized mice challenged with bacterial doses higher than LD50 survived. The antibodies were highly specific to A. baumannii and its clinical isolates. Passive immunization using serum raised against BauA protected mice from infection. BauA can be nominated as an immunogen against A. baumannii.
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Feng Y, Ruan Z, Shu J, Chen CL, Chiu CH. A glimpse into evolution and dissemination of multidrug-resistant Acinetobacter baumannii isolates in East Asia: a comparative genomics study. Sci Rep 2016; 6:24342. [PMID: 27072398 PMCID: PMC4829828 DOI: 10.1038/srep24342] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/02/2016] [Indexed: 01/27/2023] Open
Abstract
Clonal dissemination is characteristic of the important nosocomial pathogen Acinetobacter baumannii, as revealed by previous multi-locus sequence typing (MLST) studies. However, the disseminated phyletic unit is actually MLST sequence type instead of real bacterial clone. Here we sequenced the genomes of 13 multidrug-resistant (MDR) A. baumannii strains from Taiwan, and compared them with that of A. baumannii from other East Asian countries. Core-genome phylogenetic tree divided the analyzed strains into three major clades. Among them, one ST455 clade was a hybrid between the ST208 clade and the other ST455 clade. Several strains showed nearly identical genome sequence, but their isolation sources differed by over 2,500 km and 10 years apart, suggesting a wide dissemination of the phyletic units, which were much smaller than the sequence type. Frequent structural variation was detected even between the closely related strains in antimicrobial resistance elements such as AbaRI, class I integron, indicating strong selection pressure brought by antimicrobial use. In conclusion, wide clonal dissemination and frequent genomic variation simultaneously characterize the clinical MDR A. baumannii in East Asia.
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Affiliation(s)
- Ye Feng
- Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhi Ruan
- Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianfeng Shu
- Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China
| | - Chyi-Liang Chen
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Cheng-Hsun Chiu
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan.,Department of Pediatrics, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
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45
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Lean SS, Yeo CC, Suhaili Z, Thong KL. Comparative Genomics of Two ST 195 Carbapenem-Resistant Acinetobacter baumannii with Different Susceptibility to Polymyxin Revealed Underlying Resistance Mechanism. Front Microbiol 2016; 6:1445. [PMID: 26779129 PMCID: PMC4700137 DOI: 10.3389/fmicb.2015.01445] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 12/03/2015] [Indexed: 01/19/2023] Open
Abstract
Acinetobacter baumannii is a Gram-negative nosocomial pathogen of importance due to its uncanny ability to acquire resistance to most antimicrobials. These include carbapenems, which are the drugs of choice for treating A. baumannii infections, and polymyxins, the drugs of last resort. Whole genome sequencing was performed on two clinical carbapenem-resistant A. baumannii AC29 and AC30 strains which had an indistinguishable ApaI pulsotype but different susceptibilities to polymyxin. Both genomes consisted of an approximately 3.8 Mbp circular chromosome each and several plasmids. AC29 (susceptible to polymyxin) and AC30 (resistant to polymyxin) belonged to the ST195 lineage and are phylogenetically clustered under the International Clone II (IC-II) group. An AbaR4-type resistance island (RI) interrupted the comM gene in the chromosomes of both strains and contained the bla OXA-23 carbapenemase gene and determinants for tetracycline and streptomycin resistance. AC29 harbored another copy of bla OXA-23 in a large (~74 kb) conjugative plasmid, pAC29b, but this gene was absent in a similar plasmid (pAC30c) found in AC30. A 7 kb Tn1548::armA RI which encodes determinants for aminoglycoside and macrolide resistance, is chromosomally-located in AC29 but found in a 16 kb plasmid in AC30, pAC30b. Analysis of known determinants for polymyxin resistance in AC30 showed mutations in the pmrA gene encoding the response regulator of the two-component pmrAB signal transduction system as well as in the lpxD, lpxC, and lpsB genes that encode enzymes involved in the biosynthesis of lipopolysaccharide (LPS). Experimental evidence indicated that impairment of LPS along with overexpression of pmrAB may have contributed to the development of polymyxin resistance in AC30. Cloning of a novel variant of the bla AmpC gene from AC29 and AC30, and its subsequent expression in E. coli also indicated its likely function as an extended-spectrum cephalosporinase.
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Affiliation(s)
- Soo-Sum Lean
- Faulty of Science, Institute of Biological Sciences, Universiti Malaya Kuala Lumpur, Malaysia
| | - Chew Chieng Yeo
- Faculty of Medicine, Biomedical Research Centre, Universiti Sultan Zainal Abidin Kuala Terengganu, Malaysia
| | - Zarizal Suhaili
- Faculty of Bioresources and Food Industry, Universiti Sultan Zainal Abidin Kuala Terengganu, Malaysia
| | - Kwai-Lin Thong
- Faulty of Science, Institute of Biological Sciences, Universiti Malaya Kuala Lumpur, Malaysia
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Liao H, Liu M, Cheng X, Zhu D, Wang M, Jia R, Chen S, Sun K, Yang Q, Biville F, Cheng A. The Detection of Hemin-Binding Proteins in Riemerella anatipestifer CH-1. Curr Microbiol 2015; 72:152-158. [PMID: 26542531 DOI: 10.1007/s00284-015-0932-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/21/2015] [Indexed: 10/22/2022]
Abstract
Riemerella anatipestifer (R. anatipestifer) is among the most prevalent duck pathogens, causing acute or chronic septicemia characterized by serositis. Riemerella anatipestifer can be grown on blood-enriched media, in vitro, which provides a hemin source essential for the sustainment of R. anatipestifer and activation of hemin-uptake systems. However, the genes associated with hemin uptake cannot be identified exclusively through genome sequence analysis. Here, we show that R. anatipestifer encodes outer-membrane hemin-binding proteins. Hemin-binding proteins were identified in the cytoplasm with apparent molecular mass of ~45/37/33/23/20/13 kDa, and outer membrane with apparent molecular mass of ~90/70/60/50/15 kDa by batch affinity chromatography and hemin-blotting assays. Our results indicate that these proteins are involved in hemin acquisition. Finally, hemin-binding assay further showed that R. anatipestifer can bind hemin and this capability is increased in iron limited medium, indicating the hemin-uptake system of R. anatipestifer was regulated by iron.
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Affiliation(s)
- Hebin Liao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China. .,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China. .,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.
| | - Xingjun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Dekang Zhu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Kunfeng Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China
| | - Francis Biville
- Unité des Infections Bactériennes Invasives, Département Infection et Epidémiologie, Institut Pasteur, Paris, France
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China. .,Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46# Xinkang Road, Ya'an, Sichuan, 625014, P.R. China. .,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, P.R. China.
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A novel method of consensus pan-chromosome assembly and large-scale comparative analysis reveal the highly flexible pan-genome of Acinetobacter baumannii. Genome Biol 2015. [PMID: 26195261 PMCID: PMC4507327 DOI: 10.1186/s13059-015-0701-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Background Infections by pan-drug resistant Acinetobacter baumannii plague military and civilian healthcare systems. Previous A. baumannii pan-genomic studies used modest sample sizes of low diversity and comparisons to a single reference genome, limiting our understanding of gene order and content. A consensus representation of multiple genomes will provide a better framework for comparison. A large-scale comparative study will identify genomic determinants associated with their diversity and adaptation as a successful pathogen. Results We determine draft-level genomic sequence of 50 diverse military isolates and conduct the largest bacterial pan-genome analysis of 249 genomes. The pan-genome of A. baumannii is open when the input genomes are normalized for diversity with 1867 core proteins and a paralog-collapsed pan-genome size of 11,694 proteins. We developed a novel graph-based algorithm and use it to assemble the first consensus pan-chromosome, identifying both the order and orientation of core genes and flexible genomic regions. Comparative genome analyses demonstrate the existence of novel resistance islands and isolates with increased numbers of resistance island insertions over time, from single insertions in the 1950s to triple insertions in 2011. Gene clusters responsible for carbon utilization, siderophore production, and pilus assembly demonstrate frequent gain or loss among isolates. Conclusions The highly variable and dynamic nature of the A. baumannii genome may be the result of its success in rapidly adapting to both abiotic and biotic environments through the gain and loss of gene clusters controlling fitness. Importantly, some archaic adaptation mechanisms appear to have reemerged among recent isolates. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0701-6) contains supplementary material, which is available to authorized users.
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Liao H, Cheng X, Zhu D, Wang M, Jia R, Chen S, Chen X, Biville F, Liu M, Cheng A. TonB Energy Transduction Systems of Riemerella anatipestifer Are Required for Iron and Hemin Utilization. PLoS One 2015; 10:e0127506. [PMID: 26017672 PMCID: PMC4446302 DOI: 10.1371/journal.pone.0127506] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/16/2015] [Indexed: 12/13/2022] Open
Abstract
Riemerella anatipestifer (R. anatipestifer) is one of the most important pathogens in ducks. The bacteria causes acute or chronic septicemia characterized by fibrinous pericarditis and meningitis. The R. anatipestifer genome encodes multiple iron/hemin-uptake systems that facilitate adaptation to iron-limited host environments. These systems include several TonB-dependent transporters and three TonB proteins responsible for energy transduction. These three tonB genes are present in all the R. anatipestifer genomes sequenced so far. Two of these genes are contained within the exbB-exbD-tonB1 and exbB-exbD-exbD-tonB2 operons. The third, tonB3, forms a monocistronic transcription unit. The inability to recover derivatives deleted for this gene suggests its product is essential for R. anatipestifer growth. Here, we show that deletion of tonB1 had no effect on hemin uptake of R. anatipestifer, though disruption of tonB2 strongly decreases hemin uptake, and disruption of both tonB1 and tonB2 abolishes the transport of exogenously added hemin. The ability of R. anatipestifer to grow on iron-depleted medium is decreased by tonB2 but not tonB1 disruption. When expressed in an E. coli model strain, the TonB1 complex, TonB2 complex, and TonB3 protein from R. anatipestifer cannot energize heterologous hemin transporters. Further, only the TonB1 complex can energize a R. anatipestifer hemin transporter when co-expressed in an E. coli model strain.
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Affiliation(s)
- HeBin Liao
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - XingJun Cheng
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - DeKang Zhu
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - MingShu Wang
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - RenYong Jia
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - Shun Chen
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - XiaoYue Chen
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
| | - Francis Biville
- Unité des Infections Bactériennes Invasives, Institut Pasteur, Paris, France
| | - MaFeng Liu
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- * E-mail: (ML); (AC)
| | - AnChun Cheng
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Ya’an, Sichuan, People’s Republic of China
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, People’s Republic of China
- * E-mail: (ML); (AC)
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Xu S, Pan X, Luo J, Wu J, Zhou Z, Liang X, He Y, Zhou M. Effects of phenazine-1-carboxylic acid on the biology of the plant-pathogenic bacterium Xanthomonas oryzae pv. oryzae. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2015; 117:39-46. [PMID: 25619910 DOI: 10.1016/j.pestbp.2014.10.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 09/10/2014] [Accepted: 10/06/2014] [Indexed: 05/21/2023]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) is the casual agent of bacterial blight, which is one of the most serious diseases of rice. The antibiotic phenazine-1-carboxylic acid (PCA), which is primarily produced by Pseudomonas spp., was found and previously reported very effective against Xoo. However, the biological effects of PCA on Xoo remain unclear. In this study, we found that PCA increased the accumulation of reactive oxygen species (ROS) and reduced the activities of catalase (CAT) and superoxide dismutase (SOD) in Xoo. Xoo was more sensitive to H2O2 than Xanthomonas oryzae pv. oryzicola (Xoc), and had a much lower expression of CAT genes. In addition, proteomic analysis indicated that PCA inhibited carbohydrate metabolism and nutrient uptake in Xoo, and analysis of carbon source utilization further confirmed that carbohydrate metabolism in Xoo was repressed by PCA. In conclusion, PCA acted as a redox-cycling agent that disturbed the redox balance in Xoo and reduced CAT and SOD activities, resulting in higher accumulation of ROS, altered carbohydrate metabolism, and lower energy production and nutrient uptake. Moreover, a deficient antioxidant system in Xoo made it very sensitive to PCA.
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Affiliation(s)
- Shu Xu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Xiayan Pan
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Jianying Luo
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Jian Wu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Zehua Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Xiaoyu Liang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China
| | - Yawen He
- State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Mingguo Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Pesticide, Nanjing Agricultural University, Jiangsu Province, China.
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50
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Jacobs AC, Thompson MG, Gebhardt M, Corey BW, Yildirim S, Shuman HA, Zurawski DV. Genetic Manipulation of Acinetobacter baumannii. ACTA ACUST UNITED AC 2014; 35:6G.2.1-11. [PMID: 25367274 DOI: 10.1002/9780471729259.mc06g02s35] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Acinetobacter baumannii is a Gram-negative nosocomial pathogen of clinical importance. A lack of genetic tools has hindered the research of this organism in the past; however, recently, various methods have been designed, modified, and optimized to facilitate the genetic manipulation of A. baumannii. This unit describes some of the recent genetic advances and new recombinant tools developed for this pathogen, including standard transformation and conjugation techniques specifically developed for the bacteria. As the need to understand the basic biology of A. baumannii increases with the prospect of developing new therapeutics, the use of the basic genetic methods herein can provide the critical first step to identify genes required for infection.
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Affiliation(s)
- Anna C Jacobs
- Walter Reed Army Institute of Research, Department of Wound Infections, Silver Spring, Maryland
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