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Acinetobacter baumannii regulates its stress responses via the BfmRS two-component regulatory system. J Bacteriol 2021; 204:e0049421. [PMID: 34871031 DOI: 10.1128/jb.00494-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter baumannii is a common nosocomial pathogen that utilizes numerous mechanisms to aid its survival in both the environment and in the host. Coordination of such mechanisms requires an intricate regulatory network. We report here that A. baumannii can directly regulate several stress-related pathways via the two-component regulatory system, BfmRS. Similar to previous studies, results from transcriptomic analysis showed that mutation of the BfmR response regulator causes dysregulation of genes required for the oxidative stress response, the osmotic stress response, the misfolded protein/heat shock response, Csu pili/fimbriae production, and capsular polysaccharide biosynthesis. We also found that the BfmRS system is involved in controlling siderophore biosynthesis and transport, and type IV pili production. We provide evidence that BfmR binds to various stress-related promoter regions and show that BfmR alone can directly activate transcription of some stress-related genes. Additionally, we show that the BfmS sensor kinase acts as a BfmR phosphatase to negatively regulate BfmR activity. This work highlights the importance of the BfmRS system in promoting survival of A. baumannii. Importance Acinetobacter baumannii is a nosocomial pathogen that has extremely high rates of multidrug resistance. This organism's ability to endure stressful conditions is a key part of its ability to spread in the hospital environment and cause infections. Unlike other members of the γ-proteobacteria, A. baumannii does not encode a homolog of the RpoS sigma factor to coordinate its stress response. Here, we demonstrate that the BfmRS two-component system directly controls the expression of multiple stress resistance genes. Our findings suggest that BfmRS is central to a unique scheme of general stress response regulation by A. baumannii.
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Beiranvand S, Doosti A, Mirzaei SA. Putative novel B-cell vaccine candidates identified by reverse vaccinology and genomics approaches to control Acinetobacter baumannii serotypes. INFECTION GENETICS AND EVOLUTION 2021; 96:105138. [PMID: 34793968 DOI: 10.1016/j.meegid.2021.105138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 10/12/2021] [Accepted: 11/09/2021] [Indexed: 11/26/2022]
Abstract
In the last decade, Multi-drug resistance (MDR)-associated infections of Acinetobacter baumannii have grown worldwide. A cost-effective preventative strategy against this bacterium is vaccination. This study has presented five novel vaccine candidates against A. baumannii produced using the reverse vaccinology method. BLASTn was done to identify the most conserved antigens. PSORTb 3.0.2 was run to predict the subcellular localization of the proteins. The initial screening and antigenicity evaluation were performed using Vaxign. The ccSOL omics was also employed to predict protein solubility. The cross-membrane localization of the protein was predicted using PRED-TMBB. B cell epitope prediction was made for immunogenicity using the IEDB and BepiPred-2.0 database. Eventually, BLASTp was done to verify the extent of similarity to the human proteome to exclude the possibility of autoimmunity. Proteins failing to comply with the set parameters were filtered at each step. In silico, potential vaccines against 21 A. baumannii strains were identified using reverse vaccinology and subtractive genomic techniques. Based on the above criteria, out of the initial 15 A. baumannii proteins selected for screening, nine exposed/secreted/membrane proteins, i.e., Pfsr, LptE, OmpH, CarO, CsuB, CdiB, MlaA, FhuE, and were the most promising candidates. Their solubility and antigenicity were also examined and found to be more than 0.45 and 0.6, respectively. Based on the results, LptE was selected with the highest average antigenic score of 1.043 as the best protein, followed by FimF and Pfsr with scores of 1.022 and 1.014, respectively. In the end, five proteins were verified as promising candidates. Overall, the targets identified herein may be utilized in future strategies to control A. baumannii worldwide.
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Affiliation(s)
- Sheida Beiranvand
- Department of Biology, Faculty of Basic Sciences, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
| | - Abbas Doosti
- Biotechnology Research Center, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.
| | - Seyed Abbas Mirzaei
- Department of Biology, Faculty of Basic Sciences, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran; Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences, Shahrekord, Iran
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Roberge N, Neville N, Douchant K, Noordhof C, Boev N, Sjaarda C, Sheth PM, Jia Z. Broad-Spectrum Inhibitor of Bacterial Polyphosphate Homeostasis Attenuates Virulence Factors and Helps Reveal Novel Physiology of Klebsiella pneumoniae and Acinetobacter baumannii. Front Microbiol 2021; 12:764733. [PMID: 34764949 PMCID: PMC8576328 DOI: 10.3389/fmicb.2021.764733] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/04/2021] [Indexed: 12/26/2022] Open
Abstract
Acinetobacter baumannii and Klebsiella pneumoniae currently rank amongst the most antibiotic-resistant pathogens, responsible for millions of infections each year. In the wake of this crisis, anti-virulence therapeutics targeting bacterial polyphosphate (polyP) homeostasis have been lauded as an attractive alternative to traditional antibiotics. In this work, we show that the small molecule gallein, a known G-protein βγ subunit modulator, also recently proven to have dual-specificity polyphosphate kinase (PPK) inhibition in Pseudomonas aeruginosa, in turn exhibits broad-spectrum PPK inhibition in other priority pathogens. Gallein treatment successfully attenuated virulence factors of K. pneumoniae and A. baumannii including biofilm formation, surface associated motility, and offered protection against A. baumannii challenge in a Caenorhabditis elegans model of infection. This was highlighted most importantly in the critically understudied A. baumannii, where gallein treatment phenocopied a ppk1 knockout strain of a previously uncharacterized PPK1. Subsequent analysis revealed a unique instance of two functionally and phenotypically distinct PPK1 isoforms encoded by a single bacterium. Finally, gallein was administered to a defined microbial community comprising over 30 commensal species of the human gut microbiome, demonstrating the non-disruptive properties characteristic of anti-virulence treatments as microbial biodiversity was not adversely influenced. Together, these results emphasize that gallein is a promising avenue for the development of broad-spectrum anti-virulence therapeutics.
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Affiliation(s)
- Nathan Roberge
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Nolan Neville
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Katya Douchant
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada.,Gastrointestinal Disease Research Unit (GIDRU), Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Curtis Noordhof
- Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada.,Gastrointestinal Disease Research Unit (GIDRU), Department of Medicine, Queen's University, Kingston, ON, Canada
| | - Nadejda Boev
- Queen's Genomics Lab at Ongwanada (Q-GLO), Ongwanada Resource Center, Kingston, ON, Canada
| | - Calvin Sjaarda
- Queen's Genomics Lab at Ongwanada (Q-GLO), Ongwanada Resource Center, Kingston, ON, Canada.,Department of Psychiatry, Queen's University, Kingston, ON, Canada
| | - Prameet M Sheth
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada.,Department of Pathology and Molecular Medicine, Queen's University, Kingston, ON, Canada.,Gastrointestinal Disease Research Unit (GIDRU), Department of Medicine, Queen's University, Kingston, ON, Canada.,Division of Microbiology, Kingston Health Science Center, Kingston, ON, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
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Integrating transcriptomics and metabolomics analysis on kojic acid combating Acinetobacter baumannii biofilm and its potential roles. Microbiol Res 2021; 254:126911. [PMID: 34763140 DOI: 10.1016/j.micres.2021.126911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/20/2022]
Abstract
As a major secondary metabolite derived from a dominant marine filamentous fungus A7, kojic acid might confer the strain a competitive advantage in natural colonization. The bioactivities of kojic acid against bacterial growth and biofilm formation were investigated against Acinetobacter baumannii (A. baumannii) ATCC 19606. Then, transcriptomics and metabolomics were integrated to characterize the underlying mechanisms. It turned out that kojic acid exhibited a significantly suppressive impact against biofilm but a weak bacteriostatic activity. Meanwhile, a variety of transcriptional and metabolomic profiles were altered within biofilm formation as a result of kojic acid exposure. The alterations highlighted the mechanisms underlying biofilm formation, comprising of quorum sensing, fimbria assembly, bacterial virulence and metabolic plasticity, which could somewhat be hampered by kojic acid. The present study comprehensively elucidated multifactorial schemes for kojic acid combating biofilm formation of A. baumannii, which might provide mechanistic insights into the development of therapeutic strategies against this notorious pathogen. Meanwhile, our observations might shed new light on the ecological roles of kojic acid, e.g., serving as chemical deterrents for host adaptation to marine niches, which, however, awaits further validation.
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Kumar S, Anwer R, Azzi A. Virulence Potential and Treatment Options of Multidrug-Resistant (MDR) Acinetobacter baumannii. Microorganisms 2021; 9:microorganisms9102104. [PMID: 34683425 PMCID: PMC8541637 DOI: 10.3390/microorganisms9102104] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/18/2021] [Accepted: 09/21/2021] [Indexed: 12/12/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen which is undoubtedly known for a high rate of morbidity and mortality in hospital-acquired infections. A. baumannii causes life-threatening infections, including; ventilator-associated pneumonia (VAP), meningitis, bacteremia, and wound and urinary tract infections (UTI). In 2017, the World Health Organization listed A. baumannii as a priority-1 pathogen. The prevalence of A. baumannii infections and outbreaks emphasizes the direct need for the use of effective therapeutic agents for treating such infections. Available antimicrobials, such as; carbapenems, tigecycline, and colistins have insufficient effectiveness due to the appearance of multidrug-resistant strains, accentuating the need for alternative and novel therapeutic remedies. To understand and overcome this menace, the knowledge of recent discoveries on the virulence factors of A. baumannii is needed. Herein, we summarized the role of various virulence factors, including; outer membrane proteins, efflux pumps, biofilm, penicillin-binding proteins, and siderophores/iron acquisition systems. We reviewed the recent scientific literature on different A. baumannii virulence factors and the effective antimicrobial agents for the treatment and management of bacterial infections.
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Affiliation(s)
- Sunil Kumar
- Department of Biotechnology, Maharishi Markandeshwar (Deemed to Be University), Mullana, Ambala 133207, India;
| | - Razique Anwer
- Department of Pathology, College of Medicine, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13317-4233, Saudi Arabia;
| | - Arezki Azzi
- Department of Biochemistry, College of Medicine, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 13317-4233, Saudi Arabia
- Correspondence:
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Massier S, Robin B, Mégroz M, Wright A, Harper M, Hayes B, Cosette P, Broutin I, Boyce JD, Dé E, Hardouin J. Phosphorylation of Extracellular Proteins in Acinetobacter baumannii in Sessile Mode of Growth. Front Microbiol 2021; 12:738780. [PMID: 34659171 PMCID: PMC8517400 DOI: 10.3389/fmicb.2021.738780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/30/2021] [Indexed: 11/21/2022] Open
Abstract
Acinetobacter baumannii is a problematic nosocomial pathogen owing to its increasing resistance to antibiotics and its great ability to survive in the hospital environment, which is linked to its capacity to form biofilms. Structural and functional investigations of post-translational modifications, such as phosphorylations, may lead to identification of candidates for therapeutic targets against this pathogen. Here, we present the first S/T/Y phosphosecretome of two A. baumannii strains, the reference strain ATCC 17978 and the virulent multi-drug resistant strain AB0057, cultured in two modes of growth (planktonic and biofilm) using TiO2 chromatography followed by high resolution mass spectrometry. In ATCC 17978, we detected a total of 137 (97 phosphoproteins) and 52 (33 phosphoproteins) phosphosites in biofilm and planktonic modes of growth, respectively. Similarly, in AB0057, 155 (119 phosphoproteins) and 102 (74 phosphoproteins) phosphosites in biofilm and planktonic modes of growth were identified, respectively. Both strains in the biofilm mode of growth showed a higher number of phosphosites and phosphoproteins compared to planktonic growth. Several phosphorylated sites are localized in key regions of proteins involved in either drug resistance (β-lactamases), adhesion to host tissues (pilins), or protein secretion (Hcp). Site-directed mutagenesis of the Hcp protein, essential for type VI secretion system-mediated interbacterial competition, showed that four of the modified residues are essential for type VI secretion system activity.
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Affiliation(s)
- Sébastien Massier
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | - Brandon Robin
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Marianne Mégroz
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Amy Wright
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Marina Harper
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Brooke Hayes
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Pascal Cosette
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
| | | | - John D. Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Emmanuelle Dé
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
| | - Julie Hardouin
- Normandie Univ., UNIROUEN, INSA Rouen, CNRS, Polymers, Biopolymers, Surfaces Laboratory, Rouen, France
- PISSARO Proteomic Facility, IRIB, Mont-Saint-Aignan, France
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Milani ES, Hasani A, Varschochi M, Sadeghi J, Memar MY, Hasani A. Biocide resistance in Acinetobacter baumannii: appraising the mechanisms. J Hosp Infect 2021; 117:135-146. [PMID: 34560167 DOI: 10.1016/j.jhin.2021.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/14/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022]
Abstract
A global upsurge in antibiotic-resistant Acinetobacter baumannii requires supervised selection of biocides and disinfectants to avert nosocomial infections by reducing its spread. Moreover, inadequate and improper biocides have been reported as a contributing factor in antimicrobial resistance. Regardless of the manner of administration, a biocidal concentration that does not kill the target bacteria creates a stress response, propagating the resistance mechanisms. This is an essential aspect of the disinfection programme and the overall bio-contamination management plan. Knowing the mechanisms of action of biocides and resistance modalities may open new avenues to discover novel agents. This review describes the mechanisms of action of some biocides, resistance mechanisms, and approaches to study susceptibility/resistance to these agents.
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Affiliation(s)
- E S Milani
- Infectious and Tropical Diseases Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - A Hasani
- Infectious and Tropical Diseases Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Clinical Research Development Unit, Sina Educational, Research and Treatment Centre, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - M Varschochi
- Infectious and Tropical Diseases Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran
| | - J Sadeghi
- Department of Microbiology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - M Y Memar
- Infectious and Tropical Diseases Research Centre, Tabriz University of Medical Sciences, Tabriz, Iran
| | - A Hasani
- Department of Clinical Biochemistry and Laboratory Sciences, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
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Patil A, Banerji R, Kanojiya P, Saroj SD. Foodborne ESKAPE Biofilms and Antimicrobial Resistance: lessons Learned from Clinical Isolates. Pathog Glob Health 2021; 115:339-356. [PMID: 33851566 PMCID: PMC8592604 DOI: 10.1080/20477724.2021.1916158] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The ESKAPE pathogens (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are identified to be multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR); thereby, imposing severe challenges in the treatment of associated infections. ESKAPE pathogens colonize on various biotic and abiotic surfaces; biofilms formed by these pathogens are a potential source for food contamination. Moreover, biofilms play a pivotal role in the development of antimicrobial-resistant (AMR) strains. Hence, the frequent isolation of antimicrobial-resistant ESKAPE pathogens from food products across the globe imposes a threat to public health. A comprehensive understanding of the adhesion signaling involved in the polymicrobial and single-species biofilm will assist in developing alternative preservation techniques and novel therapeutic strategies to combat ESKAPE pathogens. The review provides a comprehensive overview of the signaling mechanisms that prevail in the ESKAPE pathogens for adhesion to abiotic and biotic surfaces and molecular mechanisms associated with poly-microbial biofilm-assisted AMR in ESKAPE.
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Affiliation(s)
- Amrita Patil
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Symbiosis Knowledge Village, PuneMaharashtra, India
| | - Rajashri Banerji
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Symbiosis Knowledge Village, PuneMaharashtra, India
| | - Poonam Kanojiya
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Symbiosis Knowledge Village, PuneMaharashtra, India
| | - Sunil D. Saroj
- Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Symbiosis Knowledge Village, PuneMaharashtra, India
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Li Z, Ding Z, Liu Y, Jin X, Xie J, Li T, Zeng Z, Wang Z, Liu J. Phenotypic and Genotypic Characteristics of Biofilm Formation in Clinical Isolates of Acinetobacter baumannii. Infect Drug Resist 2021; 14:2613-2624. [PMID: 34262306 PMCID: PMC8274629 DOI: 10.2147/idr.s310081] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/17/2021] [Indexed: 12/14/2022] Open
Abstract
Background Acinetobacter baumannii is an important pathogen in clinical infections, and biofilm formation is an effective way for A. baumannii to survive under external pressures. In this study, the aims were to examine the antimicrobial resistance, biofilm formation, and biofilm-specific resistance in clinical isolates of A. baumannii. Materials and Methods A total of 104 clinical A. baumannii isolates were collected from a large teaching hospital in Southwest China. The antibiotics susceptibilities were tested, and biofilm-forming ability was evaluated by crystal violet staining by confocal laser scanning microscopy (CLSM). Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) of ciprofloxacin, meropenem, and ceftazidime were tested on selected strains by broth microdilution method. Biofilm-associated genes were detected by polymerase chain reaction (PCR), and expression of genes at planktonic stage and biofilm stage were analyzed by real-time reverse transcription PCR (RT-PCR). Results Multidrug-resistant (MDR) isolates accounted for 65.4%, but no strain was resistant to tigecycline and polymyxin B. Moreover, non-MDR strains tended to form stronger biofilms than MDR strains, and a negative correlation between biofilm-forming ability and resistance profiles to each of tested antimicrobials were observed. The MBECs and MBICs of ciprofloxacin, ceftazidime, and meropenem were evidently increased compared with MICs and MBCs among all tested strains. Additionally, the biofilm formation ability of the csuD-positive strains was stronger than that of the csuD-negative strains. The strains in MDR group had higher carrying rate of csuA and csuD genes than non-MDR group, while non-MDR strains possessed more ompA gene than MDR group. Finally, abaI gene was significantly up-regulated after biofilm formation. Conclusion These results revealed valuable data for the negative correlation between antimicrobial resistance and biofilm formation, as well as phenotypic and genotypic characteristics of biofilm formation in A. baumannii.
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Affiliation(s)
- Zhaoyinqian Li
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Zixuan Ding
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Yao Liu
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Xinrui Jin
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Jingling Xie
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Tingting Li
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Zhangrui Zeng
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Zhibin Wang
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
| | - Jinbo Liu
- Department of Laboratory Medicine, the Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, People's Republic of China
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Pompilio A, Scribano D, Sarshar M, Di Bonaventura G, Palamara AT, Ambrosi C. Gram-Negative Bacteria Holding Together in a Biofilm: The Acinetobacter baumannii Way. Microorganisms 2021; 9:microorganisms9071353. [PMID: 34206680 PMCID: PMC8304980 DOI: 10.3390/microorganisms9071353] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 12/24/2022] Open
Abstract
Bacterial biofilms are a serious public-health problem worldwide. In recent years, the rates of antibiotic-resistant Gram-negative bacteria associated with biofilm-forming activity have increased worrisomely, particularly among healthcare-associated pathogens. Acinetobacter baumannii is a critically opportunistic pathogen, due to the high rates of antibiotic resistant strains causing healthcare-acquired infections (HAIs). The clinical isolates of A. baumannii can form biofilms on both biotic and abiotic surfaces; hospital settings and medical devices are the ideal environments for A. baumannii biofilms, thereby representing the main source of patient infections. However, the paucity of therapeutic options poses major concerns for human health infections caused by A. baumannii strains. The increasing number of multidrug-resistant A. baumannii biofilm-forming isolates in association with the limited number of biofilm-eradicating treatments intensify the need for effective antibiofilm approaches. This review discusses the mechanisms used by this opportunistic pathogen to form biofilms, describes their clinical impact, and summarizes the current and emerging treatment options available, both to prevent their formation and to disrupt preformed A. baumannii biofilms.
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Affiliation(s)
- Arianna Pompilio
- Center for Advanced Studies and Technology (CAST), Department of Medical, Oral and Biotechnological Sciences, Service of Clinical Microbiology, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Daniela Scribano
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy;
- Dani Di Giò Foundation-Onlus, 00193 Rome, Italy
| | - Meysam Sarshar
- Research Laboratories, Bambino Gesù Children’s Hospital, IRCCS, 00146 Rome, Italy;
| | - Giovanni Di Bonaventura
- Center for Advanced Studies and Technology (CAST), Department of Medical, Oral and Biotechnological Sciences, Service of Clinical Microbiology, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy; (A.P.); (G.D.B.)
| | - Anna Teresa Palamara
- Department of Infectious Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy;
- Laboratory Affiliated to Institute Pasteur Italia-Cenci Bolognetti Foundation, Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00185 Rome, Italy
| | - Cecilia Ambrosi
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Open University, IRCCS, 00166 Rome, Italy
- Correspondence:
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Antibiofilm and antivirulence potential of silver nanoparticles against multidrug-resistant Acinetobacter baumannii. Sci Rep 2021; 11:10751. [PMID: 34031472 PMCID: PMC8144575 DOI: 10.1038/s41598-021-90208-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 04/26/2021] [Indexed: 11/08/2022] Open
Abstract
We aimed to isolate Acinetobacter baumannii (A. baumannii) from wound infections, determine their resistance and virulence profile, and assess the impact of Silver nanoparticles (AgNPs) on the bacterial growth, virulence and biofilm-related gene expression. AgNPs were synthesized and characterized using TEM, XRD and FTIR spectroscopy. A. baumannii (n = 200) were isolated and identified. Resistance pattern was determined and virulence genes (afa/draBC, cnf1, cnf2, csgA, cvaC, fimH, fyuA, ibeA, iutA, kpsMT II, PAI, papC, PapG II, III, sfa/focDE and traT) were screened using PCR. Biofilm formation was evaluated using Microtiter plate method. Then, the antimicrobial activity of AgNPs was evaluated by the well-diffusion method, growth kinetics and MIC determination. Inhibition of biofilm formation and the ability to disperse biofilms in exposure to AgNPs were evaluated. The effect of AgNPs on the expression of virulence and biofilm-related genes (bap, OmpA, abaI, csuA/B, A1S_2091, A1S_1510, A1S_0690, A1S_0114) were estimated using QRT-PCR. In vitro infection model for analyzing the antibacterial activity of AgNPs was done using a co-culture infection model of A. baumannii with human fibroblast skin cell line HFF-1 or Vero cell lines. A. baumannii had high level of resistance to antibiotics. Most of the isolates harbored the fimH, afa/draBC, cnf1, csgA and cnf2, and the majority of A. baumannii produced strong biofilms. AgNPs inhibited the growth of A. baumannii efficiently with MIC ranging from 4 to 25 µg/ml. A. baumannii showed a reduced growth rate in the presence of AgNPs. The inhibitory activity and the anti-biofilm activity of AgNPs were more pronounced against the weak biofilm producers. Moreover, AgNPs decreased the expression of kpsMII , afa/draBC,bap, OmpA, and csuA/B genes. The in vitro infection model revealed a significant antibacterial activity of AgNPs against extracellular and intracellular A. baumannii. AgNPs highly interrupted bacterial multiplication and biofilm formation. AgNPs downregulated the transcription level of important virulence and biofilm-related genes. Our findings provide an additional step towards understanding the mechanisms by which sliver nanoparticles interfere with the microbial spread and persistence.
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Reales-Calderón JA, Sun Z, Mascaraque V, Pérez-Navarro E, Vialás V, Deutsch EW, Moritz RL, Gil C, Martínez JL, Molero G. A wide-ranging Pseudomonas aeruginosa PeptideAtlas build: A useful proteomic resource for a versatile pathogen. J Proteomics 2021; 239:104192. [PMID: 33757883 PMCID: PMC8668395 DOI: 10.1016/j.jprot.2021.104192] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/17/2021] [Accepted: 03/10/2021] [Indexed: 01/05/2023]
Abstract
Pseudomonas aeruginosa is an important opportunistic human pathogen with high prevalence in nosocomial infections. This microorganism is a good model for understanding biological processes such as the quorum-sensing response, the metabolic integration of virulence, the mechanisms of global regulation of bacterial physiology, and the evolution of antibiotic resistance. Till now, P. aeruginosa proteomic data, although available in several on-line repositories, were dispersed and difficult to access. In the present work, proteomes of the PAO1 strain grown under different conditions and from diverse cellular compartments have been joined to build the Pseudomonas PeptideAtlas. This resource is a comprehensive mass spectrometry-derived peptide and inferred protein database with 71.3% coverage of the total predicted proteome of P. aeruginosa PAO1, the highest coverage among bacterial PeptideAtlas datasets. The proteins included cover 89% of metabolic proteins, 72% of proteins involved in genetic information processing, 83% of proteins responsible for environmental information processing, more than 88% of the ones related to quorum sensing and biofilm formation, and 89% of proteins responsible for antimicrobial resistance. It exemplifies a necessary tool for targeted proteomics studies, system-wide observations, and cross-species observational studies. The manuscript describes the building of the PeptideAtlas and the contribution of the different proteomic data used. SIGNIFICANCE: Pseudomonas aeruginosa is among the most versatile human bacterial pathogens. Studies of its proteome are very important as they can reveal virulence factors and mechanisms of antibiotic resistance. The construction of a proteomic resource such as the PeptideAtlas enables targeted proteomics studies, system-wide observations, and cross-species observational studies.
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Affiliation(s)
- J A Reales-Calderón
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
| | - Z Sun
- Institute for Systems Biology, Seattle, WA, USA
| | - V Mascaraque
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
| | - E Pérez-Navarro
- Unidad de Proteómica de la Universidad Complutense de Madrid, Spain
| | - V Vialás
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain
| | - E W Deutsch
- Institute for Systems Biology, Seattle, WA, USA
| | - R L Moritz
- Institute for Systems Biology, Seattle, WA, USA
| | - C Gil
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain; Unidad de Proteómica de la Universidad Complutense de Madrid, Spain
| | - J L Martínez
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - G Molero
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad Complutense de Madrid, Spain.
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González-Montalvo MA, Tavares-Carreón F, González GM, Villanueva-Lozano H, García-Romero I, Zomosa-Signoret VC, Valvano MA, Andrade A. Defining chaperone-usher fimbriae repertoire in Serratia marcescens. Microb Pathog 2021; 154:104857. [PMID: 33762200 DOI: 10.1016/j.micpath.2021.104857] [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: 01/06/2021] [Accepted: 03/12/2021] [Indexed: 11/28/2022]
Abstract
Chaperone-usher (CU) fimbriae are surface organelles particularly prevalent among the Enterobacteriaceae. Mainly associated to their adhesive properties, CU fimbriae play key roles in biofilm formation and host cell interactions. Little is known about the fimbriome composition of the opportunistic human pathogen Serratia marcescens. Here, by using a search based on consensus fimbrial usher protein (FUP) sequences, we identified 421 FUPs across 39 S. marcescens genomes. Further analysis of the FUP-containing loci allowed us to classify them into 20 conserved CU operons, 6 of which form the S. marcescens core CU fimbriome. A new systematic nomenclature is proposed according to FUP sequence phylogeny. We also established an in vivo transcriptional assay comparing CU promoter expression between an environmental and a clinical isolate of S. marcescens, which revealed that promoters from 3 core CU operons (referred as fgov, fpo, and fps) are predominantly expressed in the two strains and might represent key core adhesion appendages contributing to S. marcescens pathogenesis.
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Affiliation(s)
- Martín A González-Montalvo
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Faviola Tavares-Carreón
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, Nuevo León, 66455, Mexico
| | - Gloria M González
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Hiram Villanueva-Lozano
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico
| | - Inmaculada García-Romero
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Viviana C Zomosa-Signoret
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Bioquímica y Medicina Molecular, Monterrey, Nuevo León, 64460, Mexico
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, United Kingdom
| | - Angel Andrade
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Departamento de Microbiología, Monterrey, Nuevo León, 64460, Mexico.
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64
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Shi J, Wu D, Su Y, Xie B. Selective enrichment of antibiotic resistance genes and pathogens on polystyrene microplastics in landfill leachate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 765:142775. [PMID: 33082042 DOI: 10.1016/j.scitotenv.2020.142775] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/30/2020] [Accepted: 09/30/2020] [Indexed: 05/11/2023]
Abstract
Landfill leachate is an important reservoir of antibiotic resistance genes (ARGs) and microplastics (MPs). However, the enrichment characteristics of ARGs on MPs and the effect of MPs' presence on ARGs in surrounding leachates are little studied. Therefore, we investigated the differences of ARGs, mobile genetic elements (MGEs), bacterial communities and pathogens on polystyrene MPs, in MPs-surrounding leachate and in control (leachate with the absence of MPs). The results revealed that ARGs were selectively enriched on MPs, which was similar in three types of leachate environments. The genes strB and blaTEM were maximally enriched and mefA, ermB, tetM and tetQ were slightly enriched on MPs, and the degree of ARGs enrichment increased with time during the 60 days of the experiment. Furthermore, compared to the leachate, MPs were observed to have the higher abundances of MGEs and distinct bacterial communities, both of which were closely associated with ARGs on MPs. Pathogens were distinct and more abundant on MPs compared to that in leachate, and 11 pathogens were identified as potential hosts for ARGs on MPs. Additionally, the presence of MPs (500 mg/L) induced few changes in ARGs' abundances, MGEs' abundances and bacterial communities in MP-surrounding leachate within 60 days. Overall, this study suggested that MPs could selectively enrich ARGs and pathogens from the surrounding environments, which promoted the understanding of the combined pollution properties of MPs and ARGs.
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Affiliation(s)
- Jianhong Shi
- Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Dong Wu
- Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Yinglong Su
- Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, East China Normal University, Shanghai 200241, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Bing Xie
- Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste, Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, East China Normal University, Shanghai 200241, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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65
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López-Martín M, Dubern JF, Alexander MR, Williams P. AbaM Regulates Quorum Sensing, Biofilm Formation, and Virulence in Acinetobacter baumannii. J Bacteriol 2021; 203:e00635-20. [PMID: 33495249 PMCID: PMC8088503 DOI: 10.1128/jb.00635-20] [Citation(s) in RCA: 30] [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: 11/17/2020] [Accepted: 01/08/2021] [Indexed: 12/31/2022] Open
Abstract
Acinetobacter baumannii possesses a single divergent luxR/luxRI-type quorum-sensing (QS) locus named abaR/abaI This locus also contains a third gene located between abaR and abaI, which we term abaM, that codes for an uncharacterized member of the RsaM protein family known to regulate N-acylhomoserine lactone (AHL)-dependent QS in other beta- and gammaproteobacteria. Here, we show that disruption of abaM via a T26 insertion in A. baumannii strain AB5075 resulted in increased production of N-(3-hydroxydodecanoyl)-l-homoserine lactone and enhanced surface motility and biofilm formation. In contrast to the wild type and the abaI::T26 mutant, the virulence of the abaM::T26 mutant was completely attenuated in a Galleria mellonella infection model. Transcriptomic analysis of the abaM::T26 mutant revealed that AbaM differentially regulates at least 76 genes, including the csu pilus operon and the acinetin 505 lipopeptide biosynthetic operon, that are involved in surface adherence, biofilm formation and virulence. A comparison of the wild type, abaM::T26 and abaI::T26 transcriptomes, indicates that AbaM regulates ∼21% of the QS regulon including the csu operon. Moreover, the QS genes (abaI and abaR) were among the most upregulated in the abaM::T26 mutant. A. baumanniilux-based abaM reporter gene fusions revealed that abaM expression is positively regulated by QS but negatively autoregulated. Overall, the data presented in this work demonstrates that AbaM plays a central role in regulating A. baumannii QS, virulence, surface motility, and biofilm formation.IMPORTANCEAcinetobacter baumannii is a multiantibiotic-resistant pathogen of global health care importance. Understanding Acinetobacter virulence gene regulation could aid the development of novel anti-infective strategies. In A. baumannii, the abaR and abaI genes that code for the receptor and synthase components of an N-acylhomoserine (AHL) lactone-dependent quorum sensing system (QS) are separated by abaM Here, we show that although mutation of abaM increased AHL production, surface motility, and biofilm development, it resulted in the attenuation of virulence. AbaM was found to control both QS-dependent and QS-independent genes. The significance of this work lies in the identification of AbaM, an RsaM ortholog known to control virulence in plant pathogens, as a modulator of virulence in a human pathogen.
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Affiliation(s)
- Mario López-Martín
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jean-Frédéric Dubern
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Morgan R Alexander
- Advanced Materials and Healthcare Technologies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Paul Williams
- Biodiscovery Institute, National Biofilms Innovation Centre, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
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66
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Acinetobacter baumannii Antibiotic Resistance Mechanisms. Pathogens 2021; 10:pathogens10030373. [PMID: 33808905 PMCID: PMC8003822 DOI: 10.3390/pathogens10030373] [Citation(s) in RCA: 190] [Impact Index Per Article: 63.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/16/2021] [Accepted: 03/18/2021] [Indexed: 12/11/2022] Open
Abstract
Acinetobacter baumannii is a Gram-negative ESKAPE microorganism that poses a threat to public health by causing severe and invasive (mostly nosocomial) infections linked with high mortality rates. During the last years, this pathogen displayed multidrug resistance (MDR), mainly due to extensive antibiotic abuse and poor stewardship. MDR isolates are associated with medical history of long hospitalization stays, presence of catheters, and mechanical ventilation, while immunocompromised and severely ill hosts predispose to invasive infections. Next-generation sequencing techniques have revolutionized diagnosis of severe A. baumannii infections, contributing to timely diagnosis and personalized therapeutic regimens according to the identification of the respective resistance genes. The aim of this review is to describe in detail all current knowledge on the genetic background of A. baumannii resistance mechanisms in humans as regards beta-lactams (penicillins, cephalosporins, carbapenems, monobactams, and beta-lactamase inhibitors), aminoglycosides, tetracyclines, fluoroquinolones, macrolides, lincosamides, streptogramin antibiotics, polymyxins, and others (amphenicols, oxazolidinones, rifamycins, fosfomycin, diaminopyrimidines, sulfonamides, glycopeptide, and lipopeptide antibiotics). Mechanisms of antimicrobial resistance refer mainly to regulation of antibiotic transportation through bacterial membranes, alteration of the antibiotic target site, and enzymatic modifications resulting in antibiotic neutralization. Virulence factors that may affect antibiotic susceptibility profiles and confer drug resistance are also being discussed. Reports from cases of A. baumannii coinfection with SARS-CoV-2 during the COVID-19 pandemic in terms of resistance profiles and MDR genes have been investigated.
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67
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Investigation of antibiofilm activity, antibacterial activity, and mechanistic studies of an amphiphilic peptide against Acinetobacter baumannii. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183600. [PMID: 33675719 DOI: 10.1016/j.bbamem.2021.183600] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 02/12/2021] [Accepted: 02/27/2021] [Indexed: 12/15/2022]
Abstract
Biofilm-producing pathogens, such as Acinetobacter baumannii, have aroused escalating attention. Because these bacteria could secrete mixture with close-knit architecture and complicated components to resist traditional antibiotics. Here, we reported an amphiphilic peptide denoted as zp3 (GIIAGIIIKIKK-NH2), which showed favorable bioactivity against Acinetobacter baumannii ATCC 19606 (minimal inhibitory concentration, MIC = 4 μM) and low cytotoxicity to mammalian cells Vero (half maximal inhibitory concentration, IC50 > 100 μM). Importantly, zp3 could inhibit the formation of biofilm at micromole level and eliminate around 50% preformed biofilm at 32 μM after 6 h treatment. This peptide was able to bind with biofilm while maintaining a helical structure in a mimic biofilm-rich environment. In vivo test demonstrated that zp3 rescued 33.3% of larvae after 48 h infection and reduced 1 log live bacteria inside the animal body after 6 h treatment. The bactericidal mode for zp3 was attributed to the combination of influencing ions balance at low concentration and inducing permeability alteration and pore formation on the Acinetobacter baumannii membrane at high concentration. Application on medical textiles also proved that zp3 could perform a good antibacterial activity in practice.
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68
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Mea HJ, Yong PVC, Wong EH. An overview of Acinetobacter baumannii pathogenesis: Motility, adherence and biofilm formation. Microbiol Res 2021; 247:126722. [PMID: 33618061 DOI: 10.1016/j.micres.2021.126722] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/13/2022]
Abstract
The Gram-negative opportunistic pathogen Acinetobacter baumannii has gain notoriety in recent decades, primarily due to its propensity to cause nosocomial infections in critically ill patients. Its global spread, multi-drug resistance features and plethora of virulence factors make it a serious threat to public health worldwide. Though much effort has been expended in uncovering its successes, it continues to confound researchers due to its highly adaptive nature, mutating to meet the needs of a given environment. Its persistence in the clinical setting allows it to be in close proximity to a potential host, where contact can be made facilitating infection and colonization. In this article, we aim to provide a current overview of the bacterial virulence factors, specifically focusing on factors involved in the initial stages of infection, highlighting the role of adaptation facilitated by two-component systems and biofilm formation. Finally, the study of host-pathogen interactions using available animal models, their suitability, notable findings and some perspectives moving forward are also discussed.
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Affiliation(s)
- Hing Jian Mea
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Phelim Voon Chen Yong
- School of Biosciences, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia
| | - Eng Hwa Wong
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University Lakeside Campus, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia.
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69
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Salisbury AM, Mullin M, Foulkes L, Chen R, Percival SL. The Ability of a Concentrated Surfactant Gel to Reduce an Aerobic, Anaerobic and Multispecies Bacterial Biofilm In Vitro. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1323:149-157. [PMID: 33433854 DOI: 10.1007/5584_2020_609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biofilm formation in wounds can lead to increased inflammation, infection and delayed wound healing. Additionally, biofilms show increased recalcitrance to antimicrobials compared to their planktonic counterparts making them difficult to manage and treat. Biofilms are frequently polymicrobial, consisting of aerobic and anaerobic bacteria, as well as fungi and yeasts. The aim of this study was to evaluate the effects of a concentrated surfactant gel with antibacterial preservative agents (CSG) against wound relevant opportunistic pathogens, including an aerobic biofilm, anaerobic biofilm and multispecies biofilm. The CSG was added to a 48 h anaerobic biofilm of Bacteroides fragilis, a 24 h multispecies biofilm of Acinetobacter baumannii, Staphylococcus aureus and Staphylococcus epidermidis and a 24 h biofilm of Pseudomonas aeruginosa grown in an in vitro wound relevant environment. Following a contact time of 24 h with the CSG, the bacterial cell density of the biofilms was reduced by 2-4 log in comparison to an untreated control. The results demonstrate the ability of the CSG to disrupt wound relevant biofilms and support the use of the CSG in the clinic to treat wounds caused by biofilm related infections.
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Affiliation(s)
- Anne-Marie Salisbury
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool, UK.
| | - Marc Mullin
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool, UK
| | - Lauren Foulkes
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool, UK
| | - Rui Chen
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool, UK
| | - Steven L Percival
- 5D Health Protection Group Ltd, Centre of Excellence in Biofilm Science (CEBS), Liverpool, UK
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70
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Kim M, Park J, Park W. Genomic and phenotypic analyses of multidrug-resistant Acinetobacter baumannii NCCP 16007 isolated from a patient with a urinary tract infection. Virulence 2020; 12:150-164. [PMID: 33372826 PMCID: PMC7781626 DOI: 10.1080/21505594.2020.1867421] [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: 11/02/2022] Open
Abstract
Polymyxin B (PMB) is increasingly used as a last-line antibiotic; however, the emergence of PMB resistance is a serious threat to global health. Here, a total of 40 Acinetobacter baumannii clinical isolates were collected to screen for PMB-resistant strains. Several clinical isolates including NCCP 16007 were far more resistant to PMB (MIC: 128-256 μg/ml) than the ATCC 17978 strain (MIC: 2 μg/ml) and appeared to possess resistance to broad-spectrum antibiotics including meropenem and 12 others. Four highly PMB-resistant strains possessed point mutations in the histidine kinase PmrB, leading to an increased expression of pmrC encoding a phosphoethanolamine transferase. Whole-genome analyses revealed that the NCCP 16007 stain had acquired two additional copies of the pmrC gene with phage integrase and 13 antibiotic resistance genes (ARGs) from other pathogens, including Klebsiella pneumoniae and Pseudomonas aeruginosa. The GC ratios of the ARGs (50-60%) were higher than that of the chromosomal backbone (39.06%), further supporting the horizontal gene transfer of ARGs. Comparative genomics with other multidrug-resistant A. baumannii strains revealed that the NCCP 16007 strain has many additional ARGs and has lost several virulence factors including Csu pili and heme oxygenase but exhibited high pathogenicity in Galleria mellonella-infection models. The observation of condensed biofilm through confocal and scanning electron microscopy suggested that the NCCP 16007 strain may possess high adhesion capacity during urinary tract infection. Therefore, our genomic and phenotypic analyses suggested that the multidrug-resistant A. baumannii NCCP 16007 strain possesses high genome plasticity, natural transformation ability, and pathogenicity.
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Affiliation(s)
- Misung Kim
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University , Seoul, Republic of Korea
| | - Jaeeun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University , Seoul, Republic of Korea
| | - Woojun Park
- Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University , Seoul, Republic of Korea
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71
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Recent Advances in the Pursuit of an Effective Acinetobacter baumannii Vaccine. Pathogens 2020; 9:pathogens9121066. [PMID: 33352688 PMCID: PMC7766458 DOI: 10.3390/pathogens9121066] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/22/2022] Open
Abstract
Acinetobacter baumannii has been a major cause of nosocomial infections for decades. The absence of an available vaccine coupled with emerging multidrug resistance has prevented the medical community from effectively controlling this human pathogen. Furthermore, the ongoing pandemic caused by SARS-CoV-2 has increased the risk of hospitalized patients developing ventilator-associated pneumonia caused by bacterial opportunists including A. baumannii. The shortage of antibiotics in the development pipeline prompted the World Health Organization to designate A. baumannii a top priority for the development of new medical countermeasures, such as a vaccine. There are a number of important considerations associated with the development of an A. baumannii vaccine, including strain characteristics, diverse disease manifestations, and target population. In the past decade, research efforts have revealed a number of promising new immunization strategies that could culminate in a safe and protective vaccine against A. baumannii. In this review, we highlight the recent progress in the development of A. baumannii vaccines, discuss potential challenges, and propose future directions to achieve an effective intervention against this human pathogen.
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72
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Gallagher P, Baker S. Developing new therapeutic approaches for treating infections caused by multi-drug resistant Acinetobacter baumannii. J Infect 2020; 81:857-861. [DOI: 10.1016/j.jinf.2020.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 10/21/2020] [Indexed: 12/23/2022]
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73
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Kurihara MNL, de Sales RO, da Silva KE, Maciel WG, Simionatto S. Multidrug-resistant Acinetobacter baumannii outbreaks: a global problem in healthcare settings. Rev Soc Bras Med Trop 2020; 53:e20200248. [PMID: 33174956 PMCID: PMC7670754 DOI: 10.1590/0037-8682-0248-2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 09/02/2020] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION The increase in the prevalence of multidrug-resistant Acinetobacter baumannii infections in hospital settings has rapidly emerged worldwide as a serious health problem. METHODS This review synthetizes the epidemiology of multidrug-resistant A. baumannii, highlighting resistance mechanisms. CONCLUSIONS Understanding the genetic mechanisms of resistance as well as the associated risk factors is critical to develop and implement adequate measures to control and prevent acquisition of nosocomial infections, especially in an intensive care unit setting.
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Affiliation(s)
| | - Romário Oliveira de Sales
- Universidade Federal da Grande Dourados, Laboratório de Pesquisa
em Ciências da Saúde, Dourados, MS, Brasil
| | - Késia Esther da Silva
- Universidade Federal da Grande Dourados, Laboratório de Pesquisa
em Ciências da Saúde, Dourados, MS, Brasil
| | - Wirlaine Glauce Maciel
- Universidade Federal da Grande Dourados, Laboratório de Pesquisa
em Ciências da Saúde, Dourados, MS, Brasil
| | - Simone Simionatto
- Universidade Federal da Grande Dourados, Laboratório de Pesquisa
em Ciências da Saúde, Dourados, MS, Brasil
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74
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Copy Number of an Integron-Encoded Antibiotic Resistance Locus Regulates a Virulence and Opacity Switch in Acinetobacter baumannii AB5075. mBio 2020; 11:mBio.02338-20. [PMID: 33024041 PMCID: PMC7542366 DOI: 10.1128/mbio.02338-20] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acinetobacter baumannii remains a leading cause of hospital-acquired infections. Widespread multidrug resistance in this species has prompted the WHO to name carbapenem-resistant A. baumannii as its top priority for research and development of new antibiotics. Many strains of A. baumannii undergo a high-frequency virulence switch, which is an attractive target for new therapeutics targeting this pathogen. This study reports a novel mechanism controlling the frequency of switching in strain AB5075. The rate of switching from the virulent opaque (VIR-O) to the avirulent translucent (AV-T) variant is positively influenced by the copy number of an antibiotic resistance locus encoded on a plasmid-borne composite integron. Our data suggest that this locus encodes a small RNA that regulates opacity switching. Low-switching opaque variants, which harbor a single copy of this locus, also exhibit decreased virulence. This study increases our understanding of this critical phenotypic switch, while also identifying potential targets for virulence-based A. baumannii treatments. We describe a novel genetic mechanism in which tandem amplification of a plasmid-borne integron regulates virulence, opacity variation, and global gene expression by altering levels of a putative small RNA (sRNA) in Acinetobacter baumannii AB5075. Copy number of this amplified locus correlated with the rate of switching between virulent opaque (VIR-O) and avirulent translucent (AV-T) cells. We found that prototypical VIR-O colonies, which exhibit high levels of switching and visible sectoring with AV-T cells by 24 h of growth, harbor two copies of this locus. However, a subset of opaque colonies that did not form AV-T sectors within 24 h were found to harbor only one copy. The colonies with decreased sectoring to AV-T were designated low-switching opaque (LSO) variants and were found to exhibit a 3-log decrease in switching relative to that of the VIR-O. Overexpression studies revealed that the element regulating switching was localized to the 5′ end of the aadB gene within the amplified locus. Northern blotting indicated that an sRNA of approximately 300 nucleotides (nt) is encoded in this region and is likely responsible for regulating switching to AV-T. Copy number of the ∼300-nt sRNA was also found to affect virulence, as the LSO variant exhibited decreased virulence during murine lung infections. Global transcriptional profiling revealed that >100 genes were differentially expressed between VIR-O and LSO variants, suggesting that the ∼300-nt sRNA may act as a global regulator. Several virulence genes exhibited decreased expression in LSO cells, potentially explaining their decreased virulence.
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Abirami G, Durgadevi R, Velmurugan P, Ravi AV. Gene expressing analysis indicates the role of Pyrogallol as a novel antibiofilm and antivirulence agent against Acinetobacter baumannii. Arch Microbiol 2020; 203:251-260. [PMID: 32918098 DOI: 10.1007/s00203-020-02026-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/14/2020] [Accepted: 09/02/2020] [Indexed: 11/28/2022]
Abstract
Acinetobacter baumannii has emerged worldwide as a leading cause of hospital-acquired infections. Although A. baumannii was initially regarded to as a low-grade pathogen, evidence has been accumulated suggesting that A. baumannii infections are associated with increased mortality in critically ill patients. Here, we describe the efficacy of pyrogallol, a polyphenolic organic compound found in the galls and barks of various trees, which shows anti-biofilm and anti-virulence potential against A. baumannii. Pyrogallol shows concentration-based biofilm inhibition, as evidenced through light and confocal laser scanning microscopic analysis. The other virulence factors are protease, swarming motility, and extracellular polymeric substances that are also inhibited by pyrogallol. Through real-time PCR, it was found that pyrogallol downregulates expression of the biofilm and virulence-related ompA, bap, csuA/B, katE, pgaA, and pgaC genes. Furthermore, pyrogallol moderately inhibited the mature biofilms of A. baumannii in a concentration-dependent manner (5, 10, and 20 µg/ml). The present study reports that the anti-biofilm and anti-virulence potential of pyrogallol disrupts the biofilm formation, adherence of cells, and cell-to-cell signaling mechanism of A. baumannii. Thus, pyrogallol is a promising therapeutic agent for A. baumannii-related infections.
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Affiliation(s)
- Gurusamy Abirami
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Ravindran Durgadevi
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Palanivel Velmurugan
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India
| | - Arumugam Veera Ravi
- Department of Biotechnology, Alagappa University, Science Campus, Karaikudi, Tamilnadu, 630003, India.
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Jiang W, Ubhayasekera W, Breed MC, Norsworthy AN, Serr N, Mobley HLT, Pearson MM, Knight SD. MrpH, a new class of metal-binding adhesin, requires zinc to mediate biofilm formation. PLoS Pathog 2020; 16:e1008707. [PMID: 32780778 PMCID: PMC7444556 DOI: 10.1371/journal.ppat.1008707] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 08/21/2020] [Accepted: 06/16/2020] [Indexed: 12/14/2022] Open
Abstract
Proteus mirabilis, a Gram-negative uropathogen, is a major causative agent in catheter-associated urinary tract infections (CAUTI). Mannose-resistant Proteus-like fimbriae (MR/P) are crucially important for P. mirabilis infectivity and are required for biofilm formation and auto-aggregation, as well as for bladder and kidney colonization. Here, the X-ray crystal structure of the MR/P tip adhesin, MrpH, is reported. The structure has a fold not previously described and contains a transition metal center with Zn2+ coordinated by three conserved histidine residues and a ligand. Using biofilm assays, chelation, metal complementation, and site-directed mutagenesis of the three histidines, we show that an intact metal binding site occupied by zinc is essential for MR/P fimbria-mediated biofilm formation, and furthermore, that P. mirabilis biofilm formation is reversible in a zinc-dependent manner. Zinc is also required for MR/P-dependent agglutination of erythrocytes, and mutation of the metal binding site renders P. mirabilis unfit in a mouse model of UTI. The studies presented here provide important clues as to the mechanism of MR/P-mediated biofilm formation and serve as a starting point for identifying the physiological MR/P fimbrial receptor. Many bacteria use fimbriae to adhere to surfaces, and this function is often essential for pathogens to gain a foothold in the host. In this study, we examine the major virulence-associated fimbrial protein, MrpH, of the bacterial urinary tract pathogen Proteus mirabilis. This species is particularly known for causing catheter-associated urinary tract infections, in which it forms damaging urinary stones and crystalline biofilms that can block the flow of urine through indwelling catheters. MrpH resides at the tip of mannose-resistant Proteus-like (MR/P) fimbriae and is required for MR/P-dependent adherence to surfaces. Although MR/P belongs to a well-known class of adhesive fimbriae encoded by the chaperone-usher pathway, we found that MrpH has a dramatically different structure compared with other tip-located adhesins in this family. Unexpectedly, MrpH was found to bind a zinc cation, which we show is essential for MR/P-mediated biofilm formation and adherence to red blood cells. Furthermore, MR/P-mediated adherence can be modified by controlling zinc levels. These findings have the potential to aid development of better anti-biofilm urinary catheters or other methods to prevent P. mirabilis infection of the urinary tract.
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Affiliation(s)
- Wangshu Jiang
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Wimal Ubhayasekera
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
| | - Michael C. Breed
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Allison N. Norsworthy
- Department of Microbiology, New York University School of Medicine, New York, NY, United States of America
| | - Nina Serr
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Harry L. T. Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
| | - Melanie M. Pearson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, United States of America
- * E-mail: (MMP); (SDK)
| | - Stefan D. Knight
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Uppsala, Sweden
- * E-mail: (MMP); (SDK)
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Monem S, Furmanek-Blaszk B, Łupkowska A, Kuczyńska-Wiśnik D, Stojowska-Swędrzyńska K, Laskowska E. Mechanisms Protecting Acinetobacter baumannii against Multiple Stresses Triggered by the Host Immune Response, Antibiotics and Outside-Host Environment. Int J Mol Sci 2020; 21:E5498. [PMID: 32752093 PMCID: PMC7432025 DOI: 10.3390/ijms21155498] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii is considered one of the most persistent pathogens responsible for nosocomial infections. Due to the emergence of multidrug resistant strains, as well as high morbidity and mortality caused by this pathogen, A. baumannii was placed on the World Health Organization (WHO) drug-resistant bacteria and antimicrobial resistance research priority list. This review summarizes current studies on mechanisms that protect A. baumannii against multiple stresses caused by the host immune response, outside host environment, and antibiotic treatment. We particularly focus on the ability of A. baumannii to survive long-term desiccation on abiotic surfaces and the population heterogeneity in A. baumannii biofilms. Insight into these protective mechanisms may provide clues for the development of new strategies to fight multidrug resistant strains of A. baumannii.
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Affiliation(s)
- Soroosh Monem
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Beata Furmanek-Blaszk
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland;
| | - Adrianna Łupkowska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Dorota Kuczyńska-Wiśnik
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Karolina Stojowska-Swędrzyńska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
| | - Ewa Laskowska
- Department of General and Medical Biochemistry, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308 Gdansk, Poland; (S.M.); (A.Ł.); (D.K.-W.); (K.S.-S.)
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In vitro Edwardsiella piscicida CK108 Transcriptome Profiles with Subinhibitory Concentrations of Phenol and Formalin Reveal New Insights into Bacterial Pathogenesis Mechanisms. Microorganisms 2020; 8:microorganisms8071068. [PMID: 32709101 PMCID: PMC7409036 DOI: 10.3390/microorganisms8071068] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 12/20/2022] Open
Abstract
Phenol and formalin are major water pollutants that are frequently discharged into the aquatic milieu. These chemicals can affect broad domains of life, including microorganisms. Aquatic pollutants, unlike terrestrial pollutants, are easily diluted in water environments and exist at a sub-inhibitory concentration (sub-IC), thus not directly inhibiting bacterial growth. However, they can modulate gene expression profiles. The sub-IC values of phenol and formalin were measured by minimal inhibitory concentration (MIC) assay to be 0.146% (1.3 mM) and 0.0039% (0.38 mM), respectively, in Edwardsiella piscicida CK108, a Gram-negative fish pathogen. We investigated the differentially expressed genes (DEG) by RNA-seq when the cells were exposed to the sub-ICs of phenol and formalin. DEG analyses revealed that genes involved in major virulence factors (type I fimbriae, flagella, type III and type VI secretion system) and various cellular pathways (energy production, amino acid synthesis, carbohydrate metabolism and two-component regulatory systems) were up- or downregulated by both chemicals. The genome-wide gene expression data corresponded to the results of a quantitative reverse complementary-PCR and motility assay. This study not only provides insight into how a representative fish pathogen, E. piscicida CK108, responds to the sub-ICs of phenol and formalin but also shows the importance of controlling chemical pollutants in aquatic environments.
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Ramezanalizadeh F, Owlia P, Rasooli I. Type I pili, CsuA/B and FimA induce a protective immune response against Acinetobacter baumannii. Vaccine 2020; 38:5436-5446. [DOI: 10.1016/j.vaccine.2020.06.052] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 06/02/2020] [Accepted: 06/18/2020] [Indexed: 12/13/2022]
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Muhammad MH, Idris AL, Fan X, Guo Y, Yu Y, Jin X, Qiu J, Guan X, Huang T. Beyond Risk: Bacterial Biofilms and Their Regulating Approaches. Front Microbiol 2020; 11:928. [PMID: 32508772 PMCID: PMC7253578 DOI: 10.3389/fmicb.2020.00928] [Citation(s) in RCA: 270] [Impact Index Per Article: 67.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/20/2020] [Indexed: 12/24/2022] Open
Abstract
Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs. Bacterial biofilm formation is a complex process and can be described in five main phases: (i) reversible attachment phase, where bacteria non-specifically attach to surfaces; (ii) irreversible attachment phase, which involves interaction between bacterial cells and a surface using bacterial adhesins such as fimbriae and lipopolysaccharide (LPS); (iii) production of extracellular polymeric substances (EPS) by the resident bacterial cells; (iv) biofilm maturation phase, in which bacterial cells synthesize and release signaling molecules to sense the presence of each other, conducing to the formation of microcolony and maturation of biofilms; and (v) dispersal/detachment phase, where the bacterial cells depart biofilms and comeback to independent planktonic lifestyle. Biofilm formation is detrimental in healthcare, drinking water distribution systems, food, and marine industries, etc. As a result, current studies have been focused toward control and prevention of biofilms. In an effort to get rid of harmful biofilms, various techniques and approaches have been employed that interfere with bacterial attachment, bacterial communication systems (quorum sensing, QS), and biofilm matrixs. Biofilms, however, also offer beneficial roles in a variety of fields including applications in plant protection, bioremediation, wastewater treatment, and corrosion inhibition amongst others. Development of beneficial biofilms can be promoted through manipulation of adhesion surfaces, QS and environmental conditions. This review describes the events involved in bacterial biofilm formation, lists the negative and positive aspects associated with bacterial biofilms, elaborates the main strategies currently used to regulate establishment of harmful bacterial biofilms as well as certain strategies employed to encourage formation of beneficial bacterial biofilms, and highlights the future perspectives of bacterial biofilms.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Tianpei Huang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & Key Laboratory of Biopesticide and Chemical Biology of Ministry of Education, College of Life Sciences & College of Plant Protection & International College, Fujian Agriculture and Forestry University, Fuzhou, China
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81
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Glycosphingolipids Recognized by Acinetobacter baumannii. Microorganisms 2020; 8:microorganisms8040612. [PMID: 32340400 PMCID: PMC7232171 DOI: 10.3390/microorganisms8040612] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/15/2020] [Accepted: 04/19/2020] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen associated with hospital-acquired infections, including pneumonia, meningitis, bacteremia, urinary tract infection, and wound infections. Recognition of host cell surface carbohydrates plays a crucial role in adhesion and enables microbes to colonize different host niches. Here the potential glycosphingolipid receptors of A. baumannii were examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. Thereby a selective interaction with two non-acid glycosphingolipids of human and rabbit small intestine was found. The binding-active glycosphingolipids were isolated and, on the basis of mass spectrometry, identified as neolactotetraosylceramide (Galβ4GlcNAcβ3Galβ4Glcβ1Cer) and lactotetraosylceramide (Galβ3GlcNAcβ3Galβ4Glcβ1Cer). Further binding assays using reference glycosphingolipids showed that A. baumannii also bound to lactotriaosylceramide (GlcNAcβ3Galβ4Glcβ1Cer) demonstrating that GlcNAc was the basic element recognized. In addition, the bacteria occasionally bound to galactosylceramide, lactosylceramide with phytosphingosine and/or hydroxy fatty acids, isoglobotriaosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide, in analogy with binding patterns that previously have been described for other bacteria classified as “lactosylceramide-binding”. Finally, by isolation and characterization of glycosphingolipids from human skin, the presence of neolactotetraosylceramide was demonstrated in this A. baumannii target tissue.
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A Cyclic-di-GMP signalling network regulates biofilm formation and surface associated motility of Acinetobacter baumannii 17978. Sci Rep 2020; 10:1991. [PMID: 32029764 PMCID: PMC7005169 DOI: 10.1038/s41598-020-58522-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/16/2020] [Indexed: 11/30/2022] Open
Abstract
Acinetobacter baumannii has emerged as an increasing multidrug-resistant threat in hospitals and a common opportunistic nosocomial pathogen worldwide. However, molecular details of the pathogenesis and physiology of this bacterium largely remain to be elucidated. Here we identify and characterize the c-di-GMP signalling network and assess its role in biofilm formation and surface associated motility. Bioinformatic analysis revealed eleven candidate genes for c-di-GMP metabolizing proteins (GGDEF/EAL domain proteins) in the genome of A. baumannii strain 17978. Enzymatic activity of the encoded proteins was assessed by molecular cloning and expression in the model organisms Salmonella typhimurium and Vibrio cholerae. Ten of the eleven GGDEF/EAL proteins altered the rdar morphotype of S. typhimurium and the rugose morphotype of V. cholerae. The over expression of three GGDEF proteins exerted a pronounced effect on colony formation of A. baumannii on Congo Red agar plates. Distinct panels of GGDEF/EAL proteins were found to alter biofilm formation and surface associated motility of A. baumannii upon over expression. The GGDEF protein A1S_3296 appeared as a major diguanylate cyclase regulating macro-colony formation, biofilm formation and the surface associated motility. AIS_3296 promotes Csu pili mediated biofilm formation. We conclude that a functional c-di-GMP signalling network in A. baumannii regulates biofilm formation and surface associated motility of this increasingly important opportunistic bacterial pathogen.
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83
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Tomar JS, Hosur RV. Polyamine acetylation and substrate-induced oligomeric states in histone acetyltransferase of multiple drug resistant Acinetobacter baumannii. Biochimie 2019; 168:268-276. [PMID: 31786230 DOI: 10.1016/j.biochi.2019.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 11/25/2019] [Indexed: 11/16/2022]
Abstract
Histone acetyltransferase (Hpa2) is an unusual acetyltransferase, with a wide range of substrates; including histones, polyamines and aminoglycosides antibiotic. Hpa2 belongs to GNAT superfamily and GNATs are well known for the formation of homo-oligomers. However, the reason behind their oligomerization remained unexplored. Here, oligomeric states of Hpa2 were explored, to understand the functional significance of oligomerization. Biochemical analysis suggests that Hpa2 exists as dimer in solution and self-assembles into tetramer in the spermine, spermidine and kanamycin bound form. Stability analysis with denaturants concludes that homo-oligomerization of Hpa2 relies on bound substrate and not on experimental conditions. Homo-oligomerization in Hpa2 depicts direct correlation with its polyamine acetylating capacity. This correlation and in silico model structures suggest that oligomerization of Hpa2 is associated with the hastening of acetylation process. Interestingly, polyamine acetylation down regulates biofilms formation in E. coli BL21/Hpa2-transformants cells. Therefore, we propose that Hpa2 manipulates survival strategies of the bacterium via polyamines and antibiotics acetylation.
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Affiliation(s)
- Jyoti Singh Tomar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India.
| | - Ramakrishna Vijayacharya Hosur
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India; UM-DAE Centre for Excellence in Basic Sciences, University Campus Mumbai, India.
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84
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Penesyan A, Nagy SS, Kjelleberg S, Gillings MR, Paulsen IT. Rapid microevolution of biofilm cells in response to antibiotics. NPJ Biofilms Microbiomes 2019; 5:34. [PMID: 31728201 PMCID: PMC6834608 DOI: 10.1038/s41522-019-0108-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/03/2019] [Indexed: 02/08/2023] Open
Abstract
Infections caused by Acinetobacter baumannii are increasingly antibiotic resistant, generating a significant public health problem. Like many bacteria, A. baumannii adopts a biofilm lifestyle that enhances its antibiotic resistance and environmental resilience. Biofilms represent the predominant mode of microbial life, but research into antibiotic resistance has mainly focused on planktonic cells. We investigated the dynamics of A. baumannii biofilms in the presence of antibiotics. A 3-day exposure of A. baumannii biofilms to sub-inhibitory concentrations of antibiotics had a profound effect, increasing biofilm formation and antibiotic resistance in the majority of biofilm dispersal isolates. Cells dispersing from biofilms were genome sequenced to identify mutations accumulating in their genomes, and network analysis linked these mutations to their phenotypes. Transcriptomics of biofilms confirmed the network analysis results, revealing novel gene functions of relevance to both resistance and biofilm formation. This approach is a rapid and objective tool for investigating resistance dynamics of biofilms.
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Affiliation(s)
- Anahit Penesyan
- 1Department of Molecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109 Australia.,2School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052 Australia
| | - Stephanie S Nagy
- 1Department of Molecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109 Australia
| | - Staffan Kjelleberg
- 3Singapore Centre for Environmental Life Sciences Engineering, 60 Nanyang Drive, SBS-01N-27, Singapore, 637551 Singapore.,4School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore.,5School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 Australia
| | - Michael R Gillings
- 6Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109 Australia
| | - Ian T Paulsen
- 1Department of Molecular Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109 Australia
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85
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Salisbury AM, Mullin M, Chen R, Percival SL. Efficacy of Poloxamer-Based Wound Dressings on Acinetobacter baumanni Biofilms. Adv Wound Care (New Rochelle) 2019; 8:463-468. [PMID: 31456903 DOI: 10.1089/wound.2018.0854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/15/2019] [Indexed: 12/17/2022] Open
Abstract
Objective: This study evaluated the antimicrobial and antibiofilm activity of a concentrated surfactant gel preserved with antimicrobials and a concentrated surfactant gel with 1% silver sulfadiazine (SSD) against 12 clinical strains of Acinetobacter baumannii and the type strain A. baumannii ATCC 19606. Approach: The biofilm-forming potential of the A. baumannii isolates was investigated using a crystal violet assay and classifying the isolates as "non-adherent," "weak," "moderate," or "strong" biofilm formers. The antimicrobial activity was determined using the zone of inhibition (ZOI) method. The antibiofilm activity was evaluated against A. baumannii ATCC 19606 using the Center for Disease Control bioreactor model. Results: A. baumannii readily forms biofilms with 8 out of the 12 clinical isolates being classified as strong biofilm formers (OD570 > 0.4). The concentrated surfactant gel with 1% SSD demonstrated antimicrobial activity against all isolates with a ZOI of 7.2-14 mm. Antibiofilm activity against a 24 h biofilm of A. baumannii ATCC 19606 was found, with a ≥7 log decrease in bacterial cell density following 24 h treatment with the concentrated surfactant gel with 1% SSD. The concentrated surfactant gel preserved with antimicrobials also showed some biofilm disruption with ∼3 log decrease in bacterial cell density being found. Innovation: The concentrated surfactant gel with 1% SSD used in this study showed antimicrobial and antibiofilm activity against A. baumannii. Conclusion: The concentrated surfactant gel with 1% SSD used in this study showed efficacy against A. baumannii, a common cause of wound infections, and should be considered for treatment of wounds infected with A. baumannii in health care settings.
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Affiliation(s)
- Anne-Marie Salisbury
- 5D Health Protection Group Ltd., Centre of Excellence in Biofilm Science, Liverpool Bio-Innovation Hub, Liverpool, United Kingdom
| | - Marc Mullin
- 5D Health Protection Group Ltd., Centre of Excellence in Biofilm Science, Liverpool Bio-Innovation Hub, Liverpool, United Kingdom
| | - Rui Chen
- 5D Health Protection Group Ltd., Centre of Excellence in Biofilm Science, Liverpool Bio-Innovation Hub, Liverpool, United Kingdom
| | - Steven L. Percival
- 5D Health Protection Group Ltd., Centre of Excellence in Biofilm Science, Liverpool Bio-Innovation Hub, Liverpool, United Kingdom
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Geisinger E, Huo W, Hernandez-Bird J, Isberg RR. Acinetobacter baumannii: Envelope Determinants That Control Drug Resistance, Virulence, and Surface Variability. Annu Rev Microbiol 2019; 73:481-506. [DOI: 10.1146/annurev-micro-020518-115714] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acinetobacter baumannii has emerged as an important nosocomial pathogen, particularly for patients in intensive care units and with invasive indwelling devices. The most recent clinical isolates are resistant to several classes of clinically important antibiotics, greatly restricting the ability to effectively treat critically ill patients. The bacterial envelope is an important driver of A. baumannii disease, both at the level of battling against antibiotic therapy and at the level of protecting from host innate immune function. This review provides a comprehensive overview of key features of the envelope that interface with both the host and antimicrobial therapies. Carbohydrate structures that contribute to protecting from the host are detailed, and mutations that alter these structures, resulting in increased antimicrobial resistance, are explored. In addition, protein complexes involved in both intermicrobial and host-microbe interactions are described. Finally we discuss regulatory mechanisms that control the nature of the cell envelope and its impact on host innate immune function.
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Affiliation(s)
- Edward Geisinger
- Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA
| | - Wenwen Huo
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
| | - Juan Hernandez-Bird
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
| | - Ralph R. Isberg
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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Raorane CJ, Lee JH, Kim YG, Rajasekharan SK, García-Contreras R, Lee J. Antibiofilm and Antivirulence Efficacies of Flavonoids and Curcumin Against Acinetobacter baumannii. Front Microbiol 2019; 10:990. [PMID: 31134028 PMCID: PMC6517519 DOI: 10.3389/fmicb.2019.00990] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/18/2019] [Indexed: 01/08/2023] Open
Abstract
Acinetobacter baumannii is well adapted to hospital environments, and the persistence of its chronic infections is mainly due to its ability to form biofilms resistant to conventional antibiotics and host immune systems. Hence, the inhibitions of biofilm formation and virulence characteristics provide other means of addressing infections. In this study, the antibiofilm activities of twelve flavonoids were initially investigated. Three most active flavonoids, namely, fisetin, phloretin, and curcumin, dose-dependently inhibited biofilm formation by a reference A. baumannii strain and by several clinical isolates, including four multidrug-resistant isolates. Furthermore, the antibiofilm activity of curcumin (the most active flavonoid) was greater than that of the well-known biofilm inhibitor gallium nitrate. Curcumin inhibited pellicle formation and the surface motility of A. baumannii. Interestingly, curcumin also showed antibiofilm activity against Candida albicans and mixed cultures of C. albicans and A. baumannii. In silico molecular docking of the biofilm response regulator BfmR showed that the binding efficacy of flavonoids with BfmR was correlated with antibiofilm efficacy. In addition, curcumin treatment diminished A. baumannii virulence in an in vivo Caenorhabditis elegans model without cytotoxicity. The study shows curcumin and other flavonoids have potential for controlling biofilm formation by and the virulence of A. baumannii.
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Affiliation(s)
| | - Jin-Hyung Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | - Yong-Guy Kim
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
| | | | - Rodolfo García-Contreras
- Department of Microbiology and Parasitology, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, South Korea
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88
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Navidifar T, Amin M, Rashno M. Effects of sub-inhibitory concentrations of meropenem and tigecycline on the expression of genes regulating pili, efflux pumps and virulence factors involved in biofilm formation by Acinetobacter baumannii. Infect Drug Resist 2019; 12:1099-1111. [PMID: 31190904 PMCID: PMC6512781 DOI: 10.2147/idr.s199993] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/16/2019] [Indexed: 12/25/2022] Open
Abstract
Background: Sub-minimal inhibitory concentrations of antibiotics have been indicated to affect the biofilm formation in pathogens of nosocomial infections. This study aimed to investigate the effects of meropenem and tigecycline at their sub-minimum inhibitory concentrations (MICs) on the biofilm formation capacity of Acinetobacter baumannii (A. baumannii), as well as the expression levels of genes involved in biofilm formation, quorum sensing, pili assembly and efflux pumps. Materials and methods: In this study, four non-clonal strains (AB10, AB13, AB32 and AB55), which were different from the aspects of antibiotic susceptibility and biofilm formation from each other were selected for the evaluation of antimicrobial susceptibility, biofilm inducibility at sub-MICs of meropenem and tigecycline and the gene expression levels (the abaI, abaR, bap, pgaA, csuE, bfmS, bfmR, ompA, adeB, adeJ and adeG genes). Result: A significant increase in the MICs of all antibiotics was demonstrated in the biofilm cells in each four strains. The biofilm formation was significantly decreased in all the representative strains exposed to tigecycline. However, the biofilm inducibility at sub-MICs of meropenem was dependent on strain genotype. In concordance with these results, Pearson correlation analysis indicated a positive significant correlation between the biofilm formation capacity and the mRNA levels of genes encoding efflux pumps except adeJ, the genes involved in biofilm formation, pili assembly and quorum sensing following exposure to meropenem and tigecycline at their sub-MICs. Conclusion: These results revealed valuable data into the correlation between the gene transcription levels and biofilm formation, as well as quorum sensing and their regulation at sub-MICs of meropenem and tigecycline.
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Affiliation(s)
- Tahereh Navidifar
- Cellular and Molecular Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mansour Amin
- Department of Microbiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Health Research Institute, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Mohammad Rashno
- Department of Immunology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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89
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Fu YY, Zhang L, Yang Y, Liu CW, He YN, Li P, Yu X. Synergistic antibacterial effect of ultrasound microbubbles combined with chitosan-modified polymyxin B-loaded liposomes on biofilm-producing Acinetobacter baumannii. Int J Nanomedicine 2019; 14:1805-1815. [PMID: 30880981 PMCID: PMC6413752 DOI: 10.2147/ijn.s186571] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Purpose Resistant strains of Acinetobacter baumannii (AB) that can form biofilms are resistant to polymyxin. Therefore, effective and safe polymyxin preparations against biofilm-producing AB are urgently needed. This study aims to prepare chitosan-modified polymyxin B-loaded liposomes (CLPs) and ultrasound microbubbles (USMBs) and then explore the synergistic antibacterial effects of USMBs combined with CLPs in vitro. Methods CLPs were prepared using a modified injection method, and microbubbles were prepared using a simple mechanical vibration method. Minimal biofilm inhibitory concentration (MBIC) of CLPs against resistant biofilm-producing AB was determined. Antibacterial activities of CLPs with or without USMBs were analyzed by crystal violet staining and resazurin assays to evaluate biofilm mass and viable counts, respectively. Then, the anti-biofilm effects of CLPs with or without USMBs on biofilm-producing AB were confirmed via scanning electron microscopy (SEM) analysis. Results We prepared CLPs that were 225.17±17.85 nm in size and carried positive charges of 12.64±1.44 mV. These CLPs, with higher encapsulation efficiency and drug loading, could exhibit a sustained release effect. We prepared microbubbles that were 2.391±0.052 µm in size and carried negative charges of −4.32±0.43 mV. The MBICs of the CLPs on the biofilm-producing AB was 8±2 µg/mL, while that of polymyxin B was 32±2 µg/mL. USMBs in combination with 2 µg/mL of polymyxin B could completely eliminate the biofilm-producing AB and achieve the maximum antimicrobial effects (P>0.05 vs sterile blank control). SEM imaging revealed some scattered bacteria without a biofilm structure in the USMB combined with the CLP group, confirming that this combination has the greatest anti-biofilm effects. Conclusion In this research, we successfully prepared USMBs and CLPs that have a more significant antibacterial effect on biofilm-forming AB than polymyxin B alone. Experiments in vitro indicate that the synergistic antibacterial effect of combining USMBs with CLPs containing as little as 2 µg/mL of polymyxin B is sufficient to almost eliminate drug-resistant biofilm-producing AB.
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Affiliation(s)
- Yu-Ying Fu
- Phase I Clinical Trial Center, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China,
| | - Liang Zhang
- Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging, Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Yi Yang
- Phase I Clinical Trial Center, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China,
| | - Cheng-Wei Liu
- State Key Laboratory of Infectious Diseases and Parasites, First Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Ying-Na He
- Department of Pharmacy, Hebei University of Chinese Medicine, Shijiazhuang, China
| | - Pan Li
- Chongqing Key Laboratory of Ultrasound Molecular Imaging, Institute of Ultrasound Imaging, Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
| | - Xian Yu
- Phase I Clinical Trial Center, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China,
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90
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Rajamani S, Sandy R, Kota K, Lundh L, Gomba G, Recabo K, Duplantier A, Panchal RG. Robust biofilm assay for quantification and high throughput screening applications. J Microbiol Methods 2019; 159:179-185. [PMID: 30826440 DOI: 10.1016/j.mimet.2019.02.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/27/2019] [Accepted: 02/27/2019] [Indexed: 01/29/2023]
Abstract
Bacterial biofilms are populations of bacteria within a self-produced adherent extracellular matrix that are notoriously resistant to treatment. Existing methods for biofilm quantification are often limited in their dynamic range of detection (signal-to-background), throughput, and require modifications to the protocol depending on the bacterial species. To address these limitations, a broad utility, high-throughput (HTP) method was required. Using a fluorescent dye, FM1-43, we stained the biofilm, followed by solvent extraction and quantitation of biofilm employing a fluorescent plate reader. Utilizing eight different bacterial pathogens, we demonstrate that this method is widely applicable for biofilm quantification. Depending on the species, this biofilm assay offered a large dynamic range of 8-146 fold change compared to 2-22 fold for crystal violet staining under similar conditions. In addition to routine biofilm quantification using this new assay, as a proof-of-concept, 1200 compounds were screened against two different bacterial species to identify biofilm inhibitors. In our HTP screens we successfully identified compounds rifabutin and ethavarine as potential biofilm inhibitors of Burkholderia pseudomallei Bp82 and Acinetobacter baumannii biofilm production respectively. This newly validated biofilm assay is robust and can be readily adapted for antibiofilm screening campaigns and can supplant other less sensitive and low throughput methods.
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Affiliation(s)
- Sathish Rajamani
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA; General Dynamics Information Technology, Frederick, MD, USA.
| | - Reuel Sandy
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA
| | - Krishna Kota
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA
| | - Linnea Lundh
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA
| | - Glenn Gomba
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA
| | - Katlin Recabo
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA
| | - Allen Duplantier
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA; Cherokee Nation Assurance, Frederick, MD, USA
| | - Rekha G Panchal
- US Army Medical Research Institute of Infectious Diseases, 1425 Porter Street, Ft. Detrick, Frederick, MD 21702, USA.
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91
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Fuqua C, Filloux A, Ghigo JM, Visick KL. Biofilms 2018: A diversity of microbes and mechanisms. J Bacteriol 2019; 201:JB.00118-19. [PMID: 30782638 PMCID: PMC6707918 DOI: 10.1128/jb.00118-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The 8th ASM Conference on Biofilms was held in Washington D.C. on October 7-11, 2018. This very highly subscribed meeting represented a wide breadth of current research in biofilms, and included over 500 attendees, 12 sessions with 64 oral presentations, and four poster sessions with about 400 posters.
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Affiliation(s)
- Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College, London, United Kingdom
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Karen L. Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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92
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De Silva PM, Kumar A. Signal Transduction Proteins in Acinetobacter baumannii: Role in Antibiotic Resistance, Virulence, and Potential as Drug Targets. Front Microbiol 2019; 10:49. [PMID: 30761101 PMCID: PMC6363711 DOI: 10.3389/fmicb.2019.00049] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 01/14/2019] [Indexed: 12/16/2022] Open
Abstract
Acinetobacter baumannii is a notorious pathogen in health care settings around the world, primarily due to high resistance to antibiotics. A. baumannii also shows an impressive capability to adapt to harsh conditions in clinical settings, which contributes to its persistence in such conditions. Following their traditional role, the Two Component Systems (TCSs) present in A. baumannii play a crucial role in sensing and adapting to the changing environmental conditions. This provides A. baumannii with a greater chance of survival even in unfavorable conditions. Since all the TCSs characterized to date in A. baumannii play a role in its antibiotic resistance and virulence, understanding the underlying molecular mechanisms behind TCSs can help with a better understanding of the pathways that regulate these phenotypes. This can also guide efforts to target TCSs as novel drug targets. In this review, we discuss the roles of TCSs in A. baumannii, their molecular mechanisms, and most importantly, the potential of using small molecule inhibitors of TCSs as potential novel drug targets.
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Affiliation(s)
- P Malaka De Silva
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada.,Manitoba Chemosensory Biology Group, University of Manitoba, Winnipeg, MB, Canada
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93
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Skerniškytė J, Krasauskas R, Péchoux C, Kulakauskas S, Armalytė J, Sužiedėlienė E. Surface-Related Features and Virulence Among Acinetobacter baumannii Clinical Isolates Belonging to International Clones I and II. Front Microbiol 2019; 9:3116. [PMID: 30671029 PMCID: PMC6331429 DOI: 10.3389/fmicb.2018.03116] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 12/03/2018] [Indexed: 01/07/2023] Open
Abstract
Acinetobacter baumannii currently represents one of the most important nosocomial infection agent due to its multidrug-resistance and a propensity for the epidemic spread. The A. baumannii strains belonging to the international clonal lineages I (IC I) and II (IC II) are associated with the hospital outbreaks and a high virulence. However, the intra and inter lineage-specific features of strains belonging to these most worldwide spread A. baumannii clones are not thoroughly explored. In this study we have investigated a set of cell surface-related features of A. baumannii IC I (n = 20) and IC II (n = 16) lineage strains, representing 30 distinct pulsed-field gel electrophoresis types in the collection of clinical isolates obtained in Lithuanian tertiary care hospitals. We show that A. baumannii IC II strains are non-motile, do not form pellicle and display distinct capsular polysaccharide profile compared with the IC I strains. Moreover, in contrast to the overall highly hydrophobic IC I strains, IC II strains showed a greater variation in cell surface hydrophobicity. Within the IC II lineage, hydrophilic strains demonstrated reduced ability to form biofilm and adhere to the abiotic surfaces, also possessed twofold thicker cell wall and exhibited higher resistance to desiccation. Furthermore, these strains showed increased adherence to the lung epithelial cells and were more virulent in nematode and mouse infection model compared with the hydrophobic IC II strains. According to the polymerase chain reaction-based locus-typing, the reduction in hydrophobicity of IC II strains was not capsule or lipooligosaccharide locus type-dependent. Hence, this study shows that the most widespread A. baumannii clonal lineages I and II markedly differ in the series of cell surface-related phenotypes including the considerable phenotypic diversification of IC II strains at the intra-lineage level. These findings suggest that the genotypically related A. baumannii strains might evolve the features which could provide an advantage at the specific conditions outside or within the host.
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Affiliation(s)
- Jūratė Skerniškytė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Renatas Krasauskas
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | | | - Saulius Kulakauskas
- INRA, MICALIS Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Julija Armalytė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Edita Sužiedėlienė
- Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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94
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El-Badawy MF, Abdelwahab SF, Alghamdi SA, Shohayeb MM. Characterization of phenotypic and genotypic traits of carbapenem-resistant Acinetobacter baumannii clinical isolates recovered from a tertiary care hospital in Taif, Saudi Arabia. Infect Drug Resist 2019; 12:3113-3124. [PMID: 31632100 PMCID: PMC6781848 DOI: 10.2147/idr.s206691] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/30/2019] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND AND OBJECTIVE Acinetobacter baumannii (A. baumannii) is a common nosocomial pathogen, which developed multi-drug-resistance to different classes of antibiotics including carbapenems. This study examined ten common carbapenemase genes among 32 carbapenem-resistant A. baumannii clinical isolates recovered from Taif, Saudi Arabia. METHODS Isolates were phenotypically identified to the genus level by Vitek®2 and API 20NE®. The species level was confirmed by the amplification of bla OXA-51. The susceptibility for 21 different antibiotics was performed by Vitek 2 and modified Kirby-Bauer method. Isolates were genetically screened for 10 carbapenemases. Phylogenetic relatedness between isolates was determined by ERIC-PCR. RESULTS Genotypically identified A. baumannii represented 100% of the total phenotypically identified Acinetobacter spp. All the carbapenem-resistant isolates were sensitive to polymyxin B and colistin. Among the other antibiotics, ampicillin/sulbactam and tigecycline were the most effective agents. 90.8% of the isolates were resistant to all ten investigated β-lactams. bla OXA-51, bla IPM, bla NDM and bla OXA-23 were detected in 100%, 87.5%, 62.5% and 59.4% of isolates, respectively. Also, bla VIM and bla OXA-40 were less prevalent and were detected in 9.3% and 3.1% of the isolates, respectively. In addition, bla KPC, bla OXA-48, bla OXA-58, bla OXA-181 were not detected in any isolate. The A. baumannii isolates were categorised into ten genotypes on the basis of the detected carbapenemase genes and ERIC-PCR revealed a remarkable clonal diversity among these isolates. CONCLUSION Class A and class D carbapenemase genes were the most commonly detected among carbapenem resistant A. baumannii (CRAB) clinical isolates.
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Affiliation(s)
- Mohamed F El-Badawy
- Division of Pharmaceutical Microbiology, Department of Pharmaceutics and Industrial Pharmacy, College of Pharmacy, Taif University, Taif21974, Kingdom of Saudi Arabia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Misr University for Science and Technology, 6th of October City12568, Egypt
| | - Sayed F Abdelwahab
- Division of Pharmaceutical Microbiology, Department of Pharmaceutics and Industrial Pharmacy, College of Pharmacy, Taif University, Taif21974, Kingdom of Saudi Arabia
- Department of Microbiology and Immunology, Faculty of Medicine, Minia University, Minia61511, Egypt
| | - Saleh A Alghamdi
- Medical Genetics, Clinical Laboratory Department, College of Applied Medical Sciences, Taif University, Taif21974, Kingdom of Saudi Arabia
| | - Mohamed M Shohayeb
- Division of Pharmaceutical Microbiology, Department of Pharmaceutics and Industrial Pharmacy, College of Pharmacy, Taif University, Taif21974, Kingdom of Saudi Arabia
- Department of Microbiology and Biotechnology, Faculty of Pharmacy, Delta University for Science and Technology, Gamasa35712, Egypt
- Correspondence: Mohamed M Shohayeb Division of Pharmaceutical Microbiology, Department of Pharmaceutics and Industrial Pharmacy, College of Pharmacy, Taif University, Taif21974, Kingdom of Saudi ArabiaTel +20 106 147 9097 Email
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95
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Ronish LA, Lillehoj E, Fields JK, Sundberg EJ, Piepenbrink KH. The structure of PilA from Acinetobacter baumannii AB5075 suggests a mechanism for functional specialization in Acinetobacter type IV pili. J Biol Chem 2018; 294:218-230. [PMID: 30413536 DOI: 10.1074/jbc.ra118.005814] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/19/2018] [Indexed: 11/06/2022] Open
Abstract
Type IV pili (T4P) are bacterial appendages composed of protein subunits, called pilins, noncovalently assembled into helical fibers. T4P are essential, in many bacterial species, for processes as diverse as twitching motility, natural competence, biofilm or microcolony formation, and host cell adhesion. The genes encoding type IV pili are found universally in the Gram-negative, aerobic, nonflagellated, and pathogenic coccobacillus Acinetobacter baumannii, but there is considerable variation in PilA, the major protein subunit, both in amino acid sequence and in glycosylation patterns. Here we report the X-ray crystal structure of PilA from AB5075, a recently characterized, highly virulent isolate, at 1.9 Å resolution and compare it to homologues from A. baumannii strains ACICU and BIDMC57, which are C-terminally glycosylated. These structural comparisons revealed that PilAAB5075 exhibits a distinctly electronegative surface chemistry. To understand the functional consequences of this change in surface electrostatics, we complemented a ΔpilA knockout strain with divergent pilA genes from ACICU, BIDMC57, and AB5075. The resulting transgenic strains showed differential twitching motility and biofilm formation while maintaining the ability to adhere to epithelial cells. PilAAB5075 and PilAACICU, although structurally similar, promote different characteristics, favoring twitching motility and biofilm formation, respectively. These results support a model in which differences in pilus electrostatics affect the equilibrium of microcolony formation, which in turn alters the balance between motility and biofilm formation in Acinetobacter.
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Affiliation(s)
- Leslie A Ronish
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Erik Lillehoj
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - James K Fields
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Eric J Sundberg
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland 21201; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland 21201; Departments of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland 21201
| | - Kurt H Piepenbrink
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Departments of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Nebraska Food for Health Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588; Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska 68588.
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96
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Pakharukova N, McKenna S, Tuittila M, Paavilainen S, Malmi H, Xu Y, Parilova O, Matthews S, Zavialov AV. Archaic and alternative chaperones preserve pilin folding energy by providing incomplete structural information. J Biol Chem 2018; 293:17070-17080. [PMID: 30228191 DOI: 10.1074/jbc.ra118.004170] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 09/14/2018] [Indexed: 11/06/2022] Open
Abstract
Adhesive pili are external component of fibrous adhesive organelles and help bacteria attach to biotic or abiotic surfaces. The biogenesis of adhesive pili via the chaperone-usher pathway (CUP) is independent of external energy sources. In the classical CUP, chaperones transport assembly-competent pilins in a folded but expanded conformation. During donor-strand exchange, pilins subsequently collapse, producing a tightly packed hydrophobic core and releasing the necessary free energy to drive fiber formation. Here, we show that pilus biogenesis in non-classical, archaic, and alternative CUPs uses a different source of conformational energy. High-resolution structures of the archaic Csu-pili system from Acinetobacter baumannii revealed that non-classical chaperones employ a short donor strand motif that is insufficient to fully complement the pilin fold. This results in chaperone-bound pilins being trapped in a substantially unfolded intermediate. The exchange of this short motif with the longer donor strand from adjacent pilin provides the full steric information essential for folding, and thereby induces a large unfolded-to-folded conformational transition to drive assembly. Our findings may inform the development of anti-adhesion drugs (pilicides) to combat bacterial infections.
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Affiliation(s)
- Natalia Pakharukova
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
| | - Sophie McKenna
- the Department of Life Sciences, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Minna Tuittila
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
| | - Sari Paavilainen
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
| | - Henri Malmi
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
| | - Yingqi Xu
- the Department of Life Sciences, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Olena Parilova
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
| | - Steve Matthews
- the Department of Life Sciences, Imperial College London, South Kensington Campus, London SW72AZ, United Kingdom
| | - Anton V Zavialov
- From the Department of Chemistry, University of Turku, Joint Biotechnology Laboratory (JBL), Arcanum, Vatselankatu 2, Turku FIN-20500, Finland and
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