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Grun CN, Jain R, Schniederberend M, Shoemaker CB, Nelson B, Kazmierczak BI. Bacterial cell surface characterization by phage display coupled to high-throughput sequencing. Nat Commun 2024; 15:7502. [PMID: 39209859 PMCID: PMC11362561 DOI: 10.1038/s41467-024-51912-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 08/19/2024] [Indexed: 09/04/2024] Open
Abstract
The remarkable capacity of bacteria to adapt in response to selective pressures drives antimicrobial resistance. Pseudomonas aeruginosa illustrates this point, establishing chronic infections during which it evolves to survive antimicrobials and evade host defenses. Many adaptive changes occur on the P. aeruginosa cell surface but methods to identify these are limited. Here we combine phage display with high-throughput DNA sequencing to create a high throughput, multiplexed technology for surveying bacterial cell surfaces, Phage-seq. By applying phage display panning to hundreds of bacterial genotypes and analyzing the dynamics of the phage display selection process, we capture important biological information about cell surfaces. This approach also yields camelid single-domain antibodies that recognize key P. aeruginosa virulence factors on live cells. These antibodies have numerous potential applications in diagnostics and therapeutics. We propose that Phage-seq establishes a powerful paradigm for studying the bacterial cell surface by identifying and profiling many surface features in parallel.
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Affiliation(s)
- Casey N Grun
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Ruchi Jain
- Department of Medicine, Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT, USA
- Piton Therapeutics, Watertown, MA, USA
| | - Maren Schniederberend
- Department of Medicine, Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT, USA
| | - Charles B Shoemaker
- Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, North Grafton, MA, USA
| | - Bryce Nelson
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
- Orion Corporation, Turku, Finland
| | - Barbara I Kazmierczak
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
- Department of Medicine, Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT, USA.
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2
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Walton B, Abbondante S, Marshall ME, Dobruchowska JM, Alvi A, Gallagher LA, Vallikat N, Zhang Z, Wozniak DJ, Yu EW, Boons GJ, Pearlman E, Rietsch A. A biofilm-tropic Pseudomonas aeruginosa bacteriophage uses the exopolysaccharide Psl as receptor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.12.607380. [PMID: 39185188 PMCID: PMC11343166 DOI: 10.1101/2024.08.12.607380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Bacteria in nature can exist in multicellular communities called biofilms. Biofilms also form in the course of many infections. Pseudomonas aeruginosa infections frequently involve biofilms, which contribute materially to the difficulty to treat these infections with antibiotic therapy. Many biofilm-related characteristics are controlled by the second messenger, cyclic-di-GMP, which is upregulated on surface contact. Among these factors is the exopolysaccharide Psl, which is a critically important component of the biofilm matrix. Here we describe the discovery of a P. aeruginosa bacteriophage, which we have called Clew-1, that directly binds to and uses Psl as a receptor. While this phage does not efficiently infect planktonically growing bacteria, it can disrupt P. aeruginosa biofilms and replicate in biofilm bacteria. We further demonstrate that the Clew-1 can reduce the bacterial burden in a mouse model of P. aeruginosa keratitis, which is characterized by the formation of a biofilm on the cornea. Due to its reliance on Psl for infection, Clew-1 does not actually form plaques on wild-type bacteria under standard in vitro conditions. This argues that our standard isolation procedures likely exclude bacteriophage that are adapted to using biofilm markers for infection. Importantly, the manner in which we isolated Clew-1 can be easily extended to other strains of P. aeruginosa and indeed other bacterial species, which will fuel the discovery of other biofilm-tropic bacteriophage and expand their therapeutic use.
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Hoffman A, Nizet V. The Prospect of Biomimetic Immune Cell Membrane-Coated Nanomedicines for Treatment of Serious Bacterial Infections and Sepsis. J Pharmacol Exp Ther 2024; 389:289-300. [PMID: 38580449 PMCID: PMC11125797 DOI: 10.1124/jpet.123.002095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 02/17/2024] [Accepted: 03/07/2024] [Indexed: 04/07/2024] Open
Abstract
Invasive bacterial infections and sepsis are persistent global health concerns, complicated further by the escalating threat of antibiotic resistance. Over the past 40 years, collaborative endeavors to improve the diagnosis and critical care of septic patients have improved outcomes, yet grappling with the intricate immune dysfunction underlying the septic condition remains a formidable challenge. Anti-inflammatory interventions that exhibited promise in murine models failed to manifest consistent survival benefits in clinical studies through recent decades. Novel therapeutic approaches that target bacterial virulence factors, for example with monoclonal antibodies, aim to thwart pathogen-driven damage and restore an advantage to the immune system. A pioneering technology addressing this challenge is biomimetic nanoparticles-a therapeutic platform featuring nanoscale particles enveloped in natural cell membranes. Borne from the quest for a durable drug delivery system, the original red blood cell-coated nanoparticles showcased a broad capacity to absorb bacterial and environmental toxins from serum. Tailoring the membrane coating to immune cell sources imparts unique characteristics to the nanoparticles suitable for broader application in infectious disease. Their capacity to bind both inflammatory signals and virulence factors assembles the most promising sepsis therapies into a singular, pathogen-agnostic therapeutic. This review explores the ongoing work on immune cell-coated nanoparticle therapeutics for infection and sepsis. SIGNIFICANCE STATEMENT: Invasive bacterial infections and sepsis are a major global health problem made worse by expanding antibiotic resistance, meaning better treatment options are urgently needed. Biomimetic cell-membrane-coated nanoparticles are an innovative therapeutic platform that deploys a multifaceted mechanism to action to neutralize microbial virulence factors, capture endotoxins, and bind excessive host proinflammatory cytokines, seeking to reduce host tissue injury, aid in microbial clearance, and improve patient outcomes.
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Affiliation(s)
- Alexandria Hoffman
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California (A.H., V.N.); and Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, California (V.N.)
| | - Victor Nizet
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, California (A.H., V.N.); and Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, La Jolla, California (V.N.)
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Fakhkhari P, Tajeddin E, Azimirad M, Salmanzadeh-Ahrabi S, Abdi-Ali A, Nikmanesh B, Eshrati B, Gouya MM, Owlia P, Zali MR, Alebouyeh M. Involvement of Pseudomonas aeruginosa in the occurrence of community and hospital acquired diarrhea, and its virulence diversity among the stool and the environmental samples. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2022; 32:61-71. [PMID: 32073302 DOI: 10.1080/09603123.2020.1726300] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Transmission of Pseudomonas aeruginosa along the food chain could cause gastrointestinal infections. To show this involvement, the prevalence, putative virulence genotype, and antibiotic resistance phenotype of P. aeruginosa isolates from stool of 1482 patients with community and hospital acquired diarrhea were compared with 87 isolates from the environmental samples. The results showed infection with P. aeruginosa in 3.4% of the cases, while 57.4% of vegetable samples were contaminated. Significantly higher frequency of lasB (98%), aprA (98%), exoY (98%), and exoS (90%), but lower rate of exoT (39.2%), was detected among the stool isolates. Multi-drug resistance (MDR) phenotype was detected in 25.5% and 4% of the stool and vegetable isolates, respectively. A higher rate of studied virulence genes was detected among the MDR strains vs non-MDR strains. These results indicate P. aeruginosa as a causative agent of diarrhea either among the hospitalized patients and those with community-acquired diarrhea.
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Affiliation(s)
- Parisa Fakhkhari
- Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Elahe Tajeddin
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoumeh Azimirad
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | | | - Ahya Abdi-Ali
- Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran
| | - Bahram Nikmanesh
- Department of Medical Laboratory Sciences, School of Allied Medical Sciences, Tehran University of Medical Sciences, Tehran, Iran
| | - Babak Eshrati
- Center for Communicable Disease Control, Ministry of Health and Medical Education, Tehran, Iran
| | - Mohammad Mehdi Gouya
- Center for Communicable Disease Control, Ministry of Health and Medical Education, Tehran, Iran
| | - Parviz Owlia
- Molecular Microbiology Research Center (MMRC), Shahed University, Tehran, Iran
| | - Mohammad Reza Zali
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoud Alebouyeh
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Pediatric Infections Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Pont S, Blanc-Potard AB. Zebrafish Embryo Infection Model to Investigate Pseudomonas aeruginosa Interaction With Innate Immunity and Validate New Therapeutics. Front Cell Infect Microbiol 2021; 11:745851. [PMID: 34660345 PMCID: PMC8515127 DOI: 10.3389/fcimb.2021.745851] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
The opportunistic human pathogen Pseudomonas aeruginosa is responsible for a variety of acute infections and is a major cause of mortality in chronically infected patients with cystic fibrosis (CF). Considering the intrinsic and acquired resistance of P. aeruginosa to currently used antibiotics, new therapeutic strategies against this pathogen are urgently needed. Whereas virulence factors of P. aeruginosa are well characterized, the interplay between P. aeruginosa and the innate immune response during infection remains unclear. Zebrafish embryo is now firmly established as a potent vertebrate model for the study of infectious human diseases, due to strong similarities of its innate immune system with that of humans and the unprecedented possibilities of non-invasive real-time imaging. This model has been successfully developed to investigate the contribution of bacterial and host factors involved in P. aeruginosa pathogenesis, as well as rapidly assess the efficacy of anti-Pseudomonas molecules. Importantly, zebrafish embryo appears as the state-of-the-art model to address in vivo the contribution of innate immunity in the outcome of P. aeruginosa infection. Of interest, is the finding that the zebrafish encodes a CFTR channel closely related to human CFTR, which allowed to develop a model to address P. aeruginosa pathogenesis, innate immune response, and treatment evaluation in a CF context.
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Affiliation(s)
- Stéphane Pont
- Laboratory of Pathogen-Host Interactions (LPHI), Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
| | - Anne-Béatrice Blanc-Potard
- Laboratory of Pathogen-Host Interactions (LPHI), Université Montpellier, Montpellier, France.,CNRS, UMR5235, Montpellier, France
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Derakhshan S, Hosseinzadeh A. Resistant Pseudomonas aeruginosa carrying virulence genes in hospitalized patients with urinary tract infection from Sanandaj, west of Iran. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fitting Pieces into the Puzzle of Pseudomonas aeruginosa Type III Secretion System Gene Expression. J Bacteriol 2019; 201:JB.00209-19. [PMID: 31010903 DOI: 10.1128/jb.00209-19] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Type III secretion systems (T3SS) are widely distributed in Gram-negative microorganisms and critical for host-pathogen and host-symbiont interactions with plants and animals. Central features of the T3SS are a highly conserved set of secretion and translocation genes and contact dependence wherein host-pathogen interactions trigger effector protein delivery and serve as an inducing signal for T3SS gene expression. In addition to these conserved features, there are pathogen-specific properties that include a unique repertoire of effector genes and mechanisms to control T3SS gene expression. The Pseudomonas aeruginosa T3SS serves as a model system to understand transcriptional and posttranscriptional mechanisms involved in the control of T3SS gene expression. The central regulatory feature is a partner-switching system that controls the DNA-binding activity of ExsA, the primary regulator of T3SS gene expression. Superimposed upon the partner-switching mechanism are cyclic AMP and cyclic di-GMP signaling systems, two-component systems, global regulators, and RNA-binding proteins that have positive and negative effects on ExsA transcription and/or synthesis. In the present review, we discuss advances in our understanding of how these regulatory systems orchestrate the activation of T3SS gene expression in the context of acute infections and repression of the T3SS as P. aeruginosa adapts to and colonizes the cystic fibrosis airways.
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8
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Host suppression of quorum sensing during catheter-associated urinary tract infections. Nat Commun 2018; 9:4436. [PMID: 30361690 PMCID: PMC6202348 DOI: 10.1038/s41467-018-06882-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 09/24/2018] [Indexed: 01/24/2023] Open
Abstract
Chronic bacterial infections on medical devices, including catheter-associated urinary tract infections (CAUTI), are associated with bacterial biofilm communities that are refractory to antibiotic therapy and resistant to host immunity. Previously, we have shown that Pseudomonas aeruginosa can cause CAUTI by forming a device-associated biofilm that is independent of known biofilm exopolysaccharides. Here, we show by RNA-seq that host urine alters the transcriptome of P. aeruginosa by suppressing quorum sensing regulated genes. P. aeruginosa produces acyl homoserine lactones (AHLs) in the presence of urea, but cannot perceive AHLs. Repression of quorum sensing by urine implies that quorum sensing should be dispensable during infection of the urinary tract. Indeed, mutants defective in quorum sensing are able to colonize similarly to wild-type in a murine model of CAUTI. Quorum sensing-regulated processes in clinical isolates are also inhibited by urea. These data show that urea in urine is a natural anti-quorum sensing mechanism in mammals.
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Chaves L, Tomich LM, Salomão M, Leite GC, Ramos J, Martins RR, Rizek C, Neves P, Batista MV, Amigo U, Guimaraes T, Levin AS, Costa SF. High mortality of bloodstream infection outbreak caused by carbapenem-resistant P. aeruginosa producing SPM-1 in a bone marrow transplant unit. J Med Microbiol 2017; 66:1722-1729. [PMID: 29095142 DOI: 10.1099/jmm.0.000631] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Carbapenem resistance in P. aeruginosa is increasing worldwide. In Brazil, SPM-1 is the main P. aeruginosa carbapenemase identified. Little is known about the virulence factor in SPM-1 clones.Methodolgy. We describe a carbapenem-resistant P. aeruginosa bloodstream infection (CRPa-BSI) outbreak in a bone marrow transplant Unit (BMT). Twenty-nine CRPa-BSI cases were compared to 58 controls. Microbiological characteristics of isolates, such as sensitivity, carbapenemase gene PCR for P. aeruginosa, and PFGE are described, as well as the whole-genome sequence (WGS) of three strains.Results/Key findings. The cultures from environmental and healthcare workers were negative. Some isolates harboured KPC and SPM. The WGS showed that the 03 strains belonged to ST277, presented the same mutations in outer membrane protein, efflux pump, and virulence genes such as those involved in adhesion, biofilm, quorum-sensing and the type III secretion system, but differ regarding the carbapenemase profile. A predominant clone-producing SPM harbouring Tn 4371 was identified and showed cross-transmission; no common source was found. Overall mortality rate among cases was 79 %. The first multivariate analysis model showed that neutropenia (P=0.018), GVHD prophylaxis (P=0.016) and prior use of carbapenems (P=0.0089) were associated with CRPa-BSI. However, when MASCC>21 points and platelets were added in the final multivariate analysis, only prior use of carbapenems remained as an independent risk factor for CRPa-BSI (P=0.043). CONCLUSIONS The predominant clone belonging to ST277 showed high mortality. Carbapenem use was the only risk factor associated with CRPa-BSI. This finding is a wake-up call for the need to improve management in BMT units.
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Affiliation(s)
- Lucas Chaves
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Lísia Moura Tomich
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Matias Salomão
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Gleice Cristina Leite
- Laboratory of Bacteriology-LIM54, Hospital das Clínicas, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Jessica Ramos
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Roberta Ruedas Martins
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Camila Rizek
- Laboratory of Bacteriology-LIM54, Hospital das Clínicas, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Patricia Neves
- Laboratory of Bacteriology-LIM54, Hospital das Clínicas, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Marjorie Vieira Batista
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
| | - Ulysses Amigo
- Bone Marrow Transplantation Unit, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Thais Guimaraes
- Infection Control Committee, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil
| | - Anna Sara Levin
- Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil.,Laboratory of Bacteriology-LIM54, Hospital das Clínicas, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Silvia Figueiredo Costa
- Laboratory of Bacteriology-LIM54, Hospital das Clínicas, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil.,Department of Infectious Diseases, School of Medicine, University of São Paulo, São Paulo, Brazil
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Aditi, Shariff M, Chhabra SK, Rahman MU. Similar virulence properties of infection and colonization associated Pseudomonas aeruginosa. J Med Microbiol 2017; 66:1489-1498. [PMID: 28893354 DOI: 10.1099/jmm.0.000569] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Pseudomonas aeruginosa is one of the agents that are commonly implicated in nosocomial infections. However, it is also present as a commensal in various body sites of healthy persons, making the diagnosis of infection by culture difficult. A number of virulence factors expressed by the organism have been implicated in its pathogenicity. We undertook this study to identify the host and organism factors associated with infection. METHODOLOGY Pathogenic, colonizing and environmental isolates were tested for apr, lasB, the T3SS effector exoenzymes (exoS, exoT, exoU and exoY) and toxA genes, biofilm production and antimicrobial susceptibility. The isolates were further typed by RAPD. RESULTS Eighty-seven isolates from 61 patients, including 11 environmental isolates, were obtained. None of the virulence factors were found to be significantly associated with infection, and nor was the antimicrobial susceptibility. The presence of the exoU gene and infection by MDR strains correlated significantly with the duration of hospital stay. Positivity for exoS and exoU genes was found to be strongly correlated with multi-drug resistance. exoU positivity correlated strongly with fluoroquinolone resistance. Sinks in the ward and intensive care unit were found to be a niche for XDR P. aeruginosa. Eighty-five isolates were typeable using the ERIC2 primer, showing 71 distinct RAPD patterns with >15 % difference in UPGMA-generated dice coefficients. CONCLUSIONS exoU positivity is associated with severe disease, as evidenced by the longer duration of hospital stay of these patients. However, the presence of virulence factors or multi-drug resistance in the cultured strain should not prompt the administration of anti-pseudomonal chemotherapy.
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Affiliation(s)
- Aditi
- Department of Microbiology, Vallabhbhai Patel Chest Institute, Delhi, India
| | - Malini Shariff
- Department of Microbiology, Vallabhbhai Patel Chest Institute, Delhi, India
| | - Sunil K Chhabra
- Department of Cardio-respiratory Physiology, Vallabhbhai Patel Chest Institute, Delhi, India
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11
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Basso P, Wallet P, Elsen S, Soleilhac E, Henry T, Faudry E, Attrée I. Multiple Pseudomonas species secrete exolysin-like toxins and provoke Caspase-1-dependent macrophage death. Environ Microbiol 2017; 19:4045-4064. [PMID: 28654176 DOI: 10.1111/1462-2920.13841] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/02/2017] [Accepted: 06/19/2017] [Indexed: 12/19/2022]
Abstract
Pathogenic bacteria secrete protein toxins that provoke apoptosis or necrosis of eukaryotic cells. Here, we developed a live-imaging method, based on incorporation of a DNA-intercalating dye into membrane-damaged host cells, to study the kinetics of primary bone marrow-derived macrophages (BMDMs) mortality induced by opportunistic pathogen Pseudomonas aeruginosa expressing either Type III Secretion System (T3SS) toxins or the pore-forming toxin, Exolysin (ExlA). We found that ExlA promotes the activation of Caspase-1 and maturation of interleukin-1β. BMDMs deficient for Caspase-1 and Caspase-11 were resistant to ExlA-induced death. Furthermore, by using KO BMDMs, we determined that the upstream NLRP3/ASC complex leads to the Caspase-1 activation. We also demonstrated that Pseudomonas putida and Pseudomonas protegens and the Drosophila pathogen Pseudomonas entomophila, which naturally express ExlA-like toxins, are cytotoxic toward macrophages and provoke the same type of pro-inflammatory death as does ExlA+ P. aeruginosa. These results demonstrate that ExlA-like toxins of two-partner secretion systems from diverse Pseudomonas species activate the NLRP3 inflammasome and provoke inflammatory pyroptotic death of macrophages.
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Affiliation(s)
- Pauline Basso
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, France
| | - Pierre Wallet
- CIRI, Centre International de Recherche en Infectiologie, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, École Normale Supérieure de Lyon, Univ Lyon, Lyon, F-69007, France
| | - Sylvie Elsen
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, France
| | - Emmanuelle Soleilhac
- CMBA Platform, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, CEA, INSERM; Genetics & Chemogenomics, France
| | - Thomas Henry
- CIRI, Centre International de Recherche en Infectiologie, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, École Normale Supérieure de Lyon, Univ Lyon, Lyon, F-69007, France
| | - Eric Faudry
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, France
| | - Ina Attrée
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, France
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Tan H, Zhang L, Zhao Q, Chen R, Liu C, Weng Y, Peng Q, Bai F, Cheng Z, Jin S, Wu W, Jin Y. DeaD contributes to Pseudomonas aeruginosa virulence in a mouse acute pneumonia model. FEMS Microbiol Lett 2016; 363:fnw227. [PMID: 27682417 DOI: 10.1093/femsle/fnw227] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2016] [Indexed: 02/05/2023] Open
Abstract
DExD/H box RNA helicases play essential roles in various biological processes in prokaryotes and eukaryotes. By screening Pseudomonas aeruginosa strains with mutations in various DExD/H box helicase genes, we identified that deaD was required for bacterial cytotoxicity and virulence in a mouse acute pneumonia model. Compared to a wild-type strain and its complementation strain, the deaD mutant induced less production of proinflammatory cytokines, neutrophil infiltration and lung damage during infection. We further found that the RNA helicase activity of DeaD was required for the expression of type III secretion system (T3SS) genes. Overexpression of ExsA, a master activator of the T3SS, restored the expression of T3SS genes as well as the virulence of the deaD mutant, suggesting that the attenuated virulence of the deaD mutant was mainly due to the defective T3SS. Overall, our results reveal a role of DeaD in the virulence of P. aeruginosa.
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Affiliation(s)
- Hao Tan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lu Zhang
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Qiang Zhao
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Ronghao Chen
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yuding Weng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Qianqian Peng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacyand Life Sciences, and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300071, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shouguang Jin
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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Affiliation(s)
- Ethan A. Rundell
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, United States of America
- Department of Medicine (Infectious Diseases), Yale University, New Haven, Connecticut, United States of America
| | - Saria A. McKeithen-Mead
- Department of Medicine (Infectious Diseases), Yale University, New Haven, Connecticut, United States of America
| | - Barbara I. Kazmierczak
- Department of Microbial Pathogenesis, Yale University, New Haven, Connecticut, United States of America
- Department of Medicine (Infectious Diseases), Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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Hassuna NA. Molecular Detection of the Virulent ExoU Genotype of Pseudomonas aeruginosa Isolated from Infected Surgical Incisions. Surg Infect (Larchmt) 2016; 17:610-4. [PMID: 27441791 DOI: 10.1089/sur.2016.065] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Pseudomonas aeruginosa is one of the major pathogens responsible for hospital-acquired infections, which harbor a wide array of virulence factors. The main aim of this study was to determine the frequency of the virulent ExoU genotype in relation to the ExoS genotype among isolated P. aeruginosa from infected surgical incisions, followed by phylogenetic analysis. METHODS A total of 66 P. aeruginosa isolates were identified by cultural and biochemical characteristics. All isolates were tested for antimicrobial susceptibility against the following antimicrobial agents: imipenem, amikacin, gentamicin, amoxycillin, cefotaxime, cefepime, and levofloxacin. Molecular detection of the ExoS and ExoU as well as two other virulence genes was done by polymerase chain reaction (PCR). Sequencing of ExoU gene and phylogenetic analysis was performed. RESULTS Approximately 81% of the isolated P. aeruginosa were multi-drug resistant. The ExoS genotype was more prevalent (63%) among the isolates than the ExoU genotype (18%), with 9% of the isolates possessing both toxins. LasB and AprA were detected in 63.6% and 27.2% of the isolates, respectively. An association was observed between the number of virulence genes and the presence of multi-drug resistance. All the ExoU were multi-drug resistant (MDR), whereas 71% of the ExoS were MDR. Phylogenetic analysis of ExoU gene showed a 99% similarity with four different strains. CONCLUSION Despite the greater frequency of the ExoS genotype, the presence of the virulent MDR ExoU genotype isolates from surgical site infections is an alarming sign requiring further intervention and investigations.
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Affiliation(s)
- Noha A Hassuna
- Department of Microbiology and Immunology, Minia University , Minia, Egypt
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Kazmierczak BI, Schniederberend M, Jain R. Cross-regulation of Pseudomonas motility systems: the intimate relationship between flagella, pili and virulence. Curr Opin Microbiol 2015; 28:78-82. [PMID: 26476804 DOI: 10.1016/j.mib.2015.07.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 07/27/2015] [Accepted: 07/29/2015] [Indexed: 10/22/2022]
Abstract
Pseudomonas aeruginosa navigates using two distinct forms of motility, swimming and twitching. A polar flagellum and Type 4 pili power these movements, respectively, allowing P. aeruginosa to attach to and colonize surfaces. Single cell imaging and particle tracking algorithms have revealed a wide range of bacterial surface behaviors which are regulated by second messengers cyclic-di-GMP and cAMP; the production of these signals is, in turn, responsive to the engagement of motility organelles with a surface. Innate immune defense systems, long known to recognize structural components of flagella, appear to respond to motility itself. The association of motility with both upregulation of virulence and induction of host defense mechanisms underlies the complex contributions of flagella and pili to P. aeruginosa pathogenesis.
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Affiliation(s)
- Barbara I Kazmierczak
- Department of Microbial Pathogenesis, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520-8022, USA; Department of Medicine (Infectious Diseases), Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520-8022, USA.
| | - Maren Schniederberend
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520-8022, USA
| | - Ruchi Jain
- Department of Medicine (Infectious Diseases), Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520-8022, USA
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Zhang JF, Zhu HY, Sun YW, Liu W, Huo YM, Liu DJ, Li J, Hua R. Pseudomonas aeruginosa Infection after Pancreatoduodenectomy: Risk Factors and Clinic Impacts. Surg Infect (Larchmt) 2015; 16:769-74. [PMID: 26237502 DOI: 10.1089/sur.2015.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of nosocomial infections, which is difficult to treat because of limited susceptibility to antimicrobial agents. In China, isolation rates of P. aeruginosa were observed to increase by year. The incidence of infectious complications after pancreatoduodenectomy (PD) were high. However, there was no data available regarding P. aeruginosa infection in patients undergoing PD. This study evaluated the risk factors and clinical impacts of P. aeruginosa infection on patient after PD. METHODS 119 patients who underwent PD with post-operative infectious complications were monitored for P. aeruginosa infection. The patients were grouped as P. aeruginosa infection and non-P. aeruginosa infection. Univariable and multivariable analyses were used to identify risk factors for P. aeruginosa infection. RESULTS 42 (35.3%) of the119 patients were P. aeruginosa positive after PD. The sites of P. aeruginosa infection included (1) abdominal drain fluid (76%); (2) sputum (7%); (3) central line catheter tip cultures (2%); and (4) combination of sites (14%). Pseudomonas aeruginosa isolates were susceptible to Polymyxin B, Amikacin and Gentamicin, resistant to Aztreonam Piperacillin-tazobactam, Imipenem and Ceftazidime. History of diabetes mellitus (OR=2.981, P=0.023), pancreatic fistula (OR=4.699, P=0.001), use of carbapenems (OR=3.236, P=0.013), and fluoroquinolones (OR=2.940, P=0.044), antibiotics, and length of ICU stay (OR=2.133, P=0.022) independently predicted post-operative P. aeruginosa infection. Pseudomonas aeruginosa infection was related to severe post-operative complications, including delayed gastric emptying and post-pancreatectomy hemorrhage, but was not related to not 30-d mortality or a longer post-operative stay. CONCLUSIONS This analytic study highlights the prevalence and high drug resistance of P. aeruginosa after PD. Pseudomonas aeruginosa infection was related to severe post-operative complications but not 30-d mortality. Measures to combat P. aeruginosa infection would likely decrease the accidence of P. aeruginosa infection and benefit patients' outcomes.
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Affiliation(s)
- Jun-Feng Zhang
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - Hong-Yan Zhu
- 2 Department of General Surgery, The First People's Hospital of Suqian, Suqian City , Jiangsu Province, China
| | - Yong-Wei Sun
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - Wei Liu
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - Yan-Miao Huo
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - De-Jun Liu
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - Jiao Li
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
| | - Rong Hua
- 1 Department of Biliary-Pancreatic Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University , Shanghai, China
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Tatke G, Kumari H, Silva-Herzog E, Ramirez L, Mathee K. Pseudomonas aeruginosa MifS-MifR Two-Component System Is Specific for α-Ketoglutarate Utilization. PLoS One 2015; 10:e0129629. [PMID: 26114434 PMCID: PMC4482717 DOI: 10.1371/journal.pone.0129629] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/10/2015] [Indexed: 12/31/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative, metabolically versatile opportunistic pathogen that elaborates a multitude of virulence factors, and is extraordinarily resistant to a gamut of clinically significant antibiotics. This ability, in part, is mediated by two-component regulatory systems (TCS) that play a crucial role in modulating virulence mechanisms and metabolism. MifS (PA5512) and MifR (PA5511) form one such TCS implicated in biofilm formation. MifS is a sensor kinase whereas MifR belongs to the NtrC superfamily of transcriptional regulators that interact with RpoN (σ54). In this study we demonstrate that the mifS and mifR genes form a two-gene operon. The close proximity of mifSR operon to poxB (PA5514) encoding a ß-lactamase hinted at the role of MifSR TCS in regulating antibiotic resistance. To better understand this TCS, clean in-frame deletions were made in P. aeruginosa PAO1 creating PAO∆mifS, PAO∆mifR and PAO∆mifSR. The loss of mifSR had no effect on the antibiotic resistance profile. Phenotypic microarray (BioLOG) analyses of PAO∆mifS and PAO∆mifR revealed that these mutants were unable to utilize C5-dicarboxylate α-ketoglutarate (α-KG), a key tricarboxylic acid cycle intermediate. This finding was confirmed using growth analyses, and the defect can be rescued by mifR or mifSR expressed in trans. These mifSR mutants were able to utilize all the other TCA cycle intermediates (citrate, succinate, fumarate, oxaloacetate or malate) and sugars (glucose or sucrose) except α-KG as the sole carbon source. We confirmed that the mifSR mutants have functional dehydrogenase complex suggesting a possible defect in α-KG transport. The inability of the mutants to utilize α-KG was rescued by expressing PA5530, encoding C5-dicarboxylate transporter, under a regulatable promoter. In addition, we demonstrate that besides MifSR and PA5530, α-KG utilization requires functional RpoN. These data clearly suggests that P. aeruginosa MifSR TCS is involved in sensing α-KG and regulating its transport and subsequent metabolism.
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Affiliation(s)
- Gorakh Tatke
- Department of Biological Sciences, College of Arts & Sciences, Florida International University, Miami, Florida, United States of America
- Department of Molecular Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - Hansi Kumari
- Department of Molecular Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - Eugenia Silva-Herzog
- Department of Molecular Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - Lourdes Ramirez
- Department of Biological Sciences, College of Arts & Sciences, Florida International University, Miami, Florida, United States of America
| | - Kalai Mathee
- Department of Molecular Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
- * E-mail:
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López Hernández Y, Yero D, Pinos-Rodríguez JM, Gibert I. Animals devoid of pulmonary system as infection models in the study of lung bacterial pathogens. Front Microbiol 2015; 6:38. [PMID: 25699030 PMCID: PMC4316775 DOI: 10.3389/fmicb.2015.00038] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/12/2015] [Indexed: 01/15/2023] Open
Abstract
Biological disease models can be difficult and costly to develop and use on a routine basis. Particularly, in vivo lung infection models performed to study lung pathologies use to be laborious, demand a great time and commonly are associated with ethical issues. When infections in experimental animals are used, they need to be refined, defined, and validated for their intended purpose. Therefore, alternative and easy to handle models of experimental infections are still needed to test the virulence of bacterial lung pathogens. Because non-mammalian models have less ethical and cost constraints as a subjects for experimentation, in some cases would be appropriated to include these models as valuable tools to explore host-pathogen interactions. Numerous scientific data have been argued to the more extensive use of several kinds of alternative models, such as, the vertebrate zebrafish (Danio rerio), and non-vertebrate insects and nematodes (e.g., Caenorhabditis elegans) in the study of diverse infectious agents that affect humans. Here, we review the use of these vertebrate and non-vertebrate models in the study of bacterial agents, which are considered the principal causes of lung injury. Curiously none of these animals have a respiratory system as in air-breathing vertebrates, where respiration takes place in lungs. Despite this fact, with the present review we sought to provide elements in favor of the use of these alternative animal models of infection to reveal the molecular signatures of host-pathogen interactions.
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Affiliation(s)
- Yamilé López Hernández
- Centro de Biociencias, Universidad Autónoma de San Luis Potosí San Luis de Potosí, Mexico
| | - Daniel Yero
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
| | - Juan M Pinos-Rodríguez
- Centro de Biociencias, Universidad Autónoma de San Luis Potosí San Luis de Potosí, Mexico
| | - Isidre Gibert
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona Barcelona, Spain ; Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona Barcelona, Spain
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Jain R, Kazmierczak BI. A conservative amino acid mutation in the master regulator FleQ renders Pseudomonas aeruginosa aflagellate. PLoS One 2014; 9:e97439. [PMID: 24827992 PMCID: PMC4020848 DOI: 10.1371/journal.pone.0097439] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2014] [Accepted: 04/17/2014] [Indexed: 11/21/2022] Open
Abstract
Flagellar-based motility plays a critical role in Pseudomonas aeruginosa pathogenesis, influencing both the establishment of bacterial infection and the host's response to the pathogen. Nonetheless, aflagellate clinical strains are often isolated from acutely and chronically infected patients and include the virulent laboratory strain PA103. We determined that PA103's aflagellate phenotype is the result of a single amino acid change (G240V) in the master flagellar regulator, FleQ. This mutation, which lies just outside the Walker B box of FleQ, abrogates the ability of FleQ to positively regulate flagellar gene expression. Reversal of this seemingly conservative amino acid substitution is sufficient to restore swimming motility to PA103, despite the presence of mutations in other flagellar genes of PA103. We also investigated the consequences of restoring flagellar assembly on PA103 virulence. Although a negative correlation between flagellar assembly and Type 3 secretion system (T3SS) expression has been reported previously, we did not observe downregulation of T3SS expression or function in Fla+ PA103. Restoration of flagellar assembly did, however, amplify IL-1 signals measured during murine pulmonary infection and was associated with increased bacterial clearance. These experiments suggest that loss of flagellar motility may primarily benefit PA103 by attenuating pathogen recognition and clearance during acute infection.
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Affiliation(s)
- Ruchi Jain
- Department of Internal Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Barbara I. Kazmierczak
- Department of Internal Medicine (Infectious Diseases), Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, United States of America
- * E-mail:
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Cheating by type 3 secretion system-negative Pseudomonas aeruginosa during pulmonary infection. Proc Natl Acad Sci U S A 2014; 111:7801-6. [PMID: 24821799 DOI: 10.1073/pnas.1400782111] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The opportunistic pathogen Pseudomonas aeruginosa expresses a type 3 secretion system (T3SS) strongly associated with bacterial virulence in murine models and human patients. T3SS effectors target host innate immune mechanisms, and T3SS-defective mutants are cleared more efficiently than T3SS-positive bacteria by an immunocompetent host. Nonetheless, T3SS-negative isolates are recovered from many patients with documented P. aeruginosa infections, leading us to test whether T3SS-negative strains could have a selective advantage during in vivo infection. Mice were infected with mixtures of T3SS-positive WT P. aeruginosa plus isogenic T3SS-OFF or constitutively T3SS-ON mutants. Relative fitness of bacteria in this acute pneumonia model was reflected by the competitive index of mutants relative to WT. T3SS-OFF strains outcompeted WT PA103 in vivo, whereas a T3SS-ON mutant showed decreased fitness compared with WT. In vitro growth rates of WT and T3SS-OFF bacteria were determined under T3SS-inducing conditions and did not differ significantly. Increased fitness of T3SS-OFF bacteria was no longer observed at high ratios of T3SS-OFF to WT, a feature characteristic of bacterial cheaters. Cheating by T3SS-OFF bacteria occurred only when T3SS-positive bacteria expressed the phospholipase A2 effector Exotoxin U (ExoU). T3SS-OFF bacteria showed no fitness advantage in competition experiments carried out in immunodeficient MyD88-knockout mice or in neutrophil-depleted animals. Our findings indicate that T3SS-negative isolates benefit from the public good provided by ExoU-mediated killing of recruited innate immune cells. Whether this transient increase in fitness observed for T3SS-negative strains in mice contributes to the observed persistence of T3SS-negative isolates in humans is of ongoing interest.
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Morfín-Otero R, Alcántar-Curiel M, Rocha M, Alpuche-Aranda C, Santos-Preciado J, Gayosso-Vázquez C, Araiza-Navarro J, Flores-Vaca M, Esparza-Ahumada S, González-Díaz E, Pérez-Gómez H, Rodríguez-Noriega E. Acinetobacter baumannii Infections in a Tertiary Care Hospital in Mexico over the Past 13 Years. Chemotherapy 2013; 59:57-65. [DOI: 10.1159/000351098] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 03/26/2013] [Indexed: 11/19/2022]
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