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Madden DE, Baird T, Bell SC, McCarthy KL, Price EP, Sarovich DS. Keeping up with the pathogens: improved antimicrobial resistance detection and prediction from Pseudomonas aeruginosa genomes. Genome Med 2024; 16:78. [PMID: 38849863 PMCID: PMC11157771 DOI: 10.1186/s13073-024-01346-z] [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: 10/29/2023] [Accepted: 05/20/2024] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND Antimicrobial resistance (AMR) is an intensifying threat that requires urgent mitigation to avoid a post-antibiotic era. Pseudomonas aeruginosa represents one of the greatest AMR concerns due to increasing multi- and pan-drug resistance rates. Shotgun sequencing is gaining traction for in silico AMR profiling due to its unambiguity and transferability; however, accurate and comprehensive AMR prediction from P. aeruginosa genomes remains an unsolved problem. METHODS We first curated the most comprehensive database yet of known P. aeruginosa AMR variants. Next, we performed comparative genomics and microbial genome-wide association study analysis across a Global isolate Dataset (n = 1877) with paired antimicrobial phenotype and genomic data to identify novel AMR variants. Finally, the performance of our P. aeruginosa AMR database, implemented in our AMR detection and prediction tool, ARDaP, was compared with three previously published in silico AMR gene detection or phenotype prediction tools-abritAMR, AMRFinderPlus, ResFinder-across both the Global Dataset and an analysis-naïve Validation Dataset (n = 102). RESULTS Our AMR database comprises 3639 mobile AMR genes and 728 chromosomal variants, including 75 previously unreported chromosomal AMR variants, 10 variants associated with unusual antimicrobial susceptibility, and 281 chromosomal variants that we show are unlikely to confer AMR. Our pipeline achieved a genotype-phenotype balanced accuracy (bACC) of 85% and 81% across 10 clinically relevant antibiotics when tested against the Global and Validation Datasets, respectively, vs. just 56% and 54% with abritAMR, 58% and 54% with AMRFinderPlus, and 60% and 53% with ResFinder. ARDaP's superior performance was predominantly due to the inclusion of chromosomal AMR variants, which are generally not identified with most AMR identification tools. CONCLUSIONS Our ARDaP software and associated AMR variant database provides an accurate tool for predicting AMR phenotypes in P. aeruginosa, far surpassing the performance of current tools. Implementation of ARDaP for routine AMR prediction from P. aeruginosa genomes and metagenomes will improve AMR identification, addressing a critical facet in combatting this treatment-refractory pathogen. However, knowledge gaps remain in our understanding of the P. aeruginosa resistome, particularly the basis of colistin AMR.
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Affiliation(s)
- Danielle E Madden
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Timothy Baird
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
- Respiratory Department, Sunshine Coast University Hospital, Birtinya, Queensland, Australia
| | - Scott C Bell
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, Queensland, Australia
- Children's Health Research Centre, Faculty of Medicine, The University of Queensland, South Brisbane, Queensland, Australia
| | - Kate L McCarthy
- University of Queensland Medical School, Herston, QLD, Australia
- Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
| | - Erin P Price
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Derek S Sarovich
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, QLD, Australia.
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia.
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2
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Jiang B, Qiu H, Lu C, Lu M, Li Y, Dai W. Uncovering the GacS-mediated role in evolutionary progression through trajectory reconstruction in Pseudomonas aeruginosa. Nucleic Acids Res 2024; 52:3856-3869. [PMID: 38477346 DOI: 10.1093/nar/gkae187] [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: 10/05/2023] [Revised: 02/23/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024] Open
Abstract
The genetic diversities of subpopulations drive the evolution of pathogens and affect their ability to infect hosts and cause diseases. However, most studies to date have focused on the identification and characterization of adaptive mutations in single colonies, which do not accurately reflect the phenotypes of an entire population. Here, to identify the composition of variant subpopulations within a pathogen population, we developed a streamlined approach that combines high-throughput sequencing of the entire population cells with genotyping of single colonies. Using this method, we reconstructed a detailed quorum-sensing (QS) evolutionary trajectory in Pseudomonas aeruginosa. Our results revealed a new adaptive mutation in the gacS gene, which codes for a histidine kinase sensor of a two-component system (TCS), during QS evolution. This mutation reduced QS activity, allowing the variant to sweep throughout the whole population, while still being vulnerable to invasion by the emerging QS master regulator LasR-null mutants. By tracking the evolutionary trajectory, we found that mutations in gacS facilitated QS-rewiring in the LasR-null mutant. This rapid QS revertant caused by inactive GacS was found to be associated with the promotion of ribosome biogenesis and accompanied by a trade-off of reduced bacterial virulence on host cells. In conclusion, our findings highlight the crucial role of the global regulator GacS in modulating the progression of QS evolution and the virulence of the pathogen population.
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Affiliation(s)
- Bo Jiang
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Huifang Qiu
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Chenghui Lu
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Mingqi Lu
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yuanhao Li
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Weijun Dai
- Integrative Microbiology Research Center, College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
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Nozick SH, Ozer EA, Medernach R, Kochan TJ, Kumar R, Mills JO, Wunderlink RG, Qi C, Hauser AR. Phenotypes of a Pseudomonas aeruginosa hypermutator lineage that emerged during prolonged mechanical ventilation in a patient without cystic fibrosis. mSystems 2024; 9:e0048423. [PMID: 38132670 PMCID: PMC10804958 DOI: 10.1128/msystems.00484-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 11/13/2023] [Indexed: 12/23/2023] Open
Abstract
Hypermutator lineages of Pseudomonas aeruginosa arise frequently during the years of airway infection experienced by patients with cystic fibrosis and bronchiectasis but are rare in the absence of chronic infection and structural lung disease. Since the onset of the COVID-19 pandemic, large numbers of patients have remained mechanically ventilated for extended periods of time. These patients are prone to acquire bacterial pathogens that persist for many weeks and have the opportunity to evolve within the pulmonary environment. However, little is known about what types of adaptations occur in these bacteria and whether these adaptations mimic those observed in chronic infections. We describe a COVID-19 patient with a secondary P. aeruginosa lung infection in whom the causative bacterium persisted for >50 days. Over the course of this infection, a hypermutator lineage of P. aeruginosa emerged and co-existed with a non-hypermutator lineage. Compared to the parental lineage, the hypermutator lineage evolved to be less cytotoxic and less virulent. Genomic analyses of the hypermutator lineage identified numerous mutations, including in the mismatch repair gene mutL and other genes frequently mutated in individuals with cystic fibrosis. Together, these findings demonstrate that hypermutator lineages can emerge when P. aeruginosa persists following acute infections such as ventilator-associated pneumonia and that these lineages have the potential to affect patient outcomes.IMPORTANCEPseudomonas aeruginosa may evolve to accumulate large numbers of mutations in the context of chronic infections such as those that occur in individuals with cystic fibrosis. However, these "hypermutator" lineages are rare following acute infections. Here, we describe a non-cystic fibrosis patient with COVID-19 pneumonia who remained mechanically ventilated for months. The patient became infected with a strain of P. aeruginosa that evolved to become a hypermutator. We demonstrate that hypermutation led to changes in cytotoxicity and virulence. These findings are important because they demonstrate that P. aeruginosa hypermutators can emerge following acute infections and that they have the potential to affect patient outcomes in this setting.
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Affiliation(s)
- Sophia H. Nozick
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Egon A. Ozer
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Center for Pathogen Genomics and Microbial Evolution, Robert J. Havey Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rachel Medernach
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Travis J. Kochan
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rebecca Kumar
- />Department of Medicine, Division of Infectious Diseases, Georgetown University, Washington, DC, USA
| | - Jori O. Mills
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Richard G. Wunderlink
- Department of Medicine, Division of Pulmonary and Critical Care, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Chao Qi
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alan R. Hauser
- Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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4
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Ruhluel D, Fisher L, Barton TE, Leighton H, Kumar S, Amores Morillo P, O’Brien S, Fothergill JL, Neill DR. Secondary messenger signalling influences Pseudomonas aeruginosa adaptation to sinus and lung environments. THE ISME JOURNAL 2024; 18:wrae065. [PMID: 38647527 PMCID: PMC11102083 DOI: 10.1093/ismejo/wrae065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Revised: 03/08/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Pseudomonas aeruginosa is a cause of chronic respiratory tract infections in people with cystic fibrosis (CF), non-CF bronchiectasis, and chronic obstructive pulmonary disease. Prolonged infection allows the accumulation of mutations and horizontal gene transfer, increasing the likelihood of adaptive phenotypic traits. Adaptation is proposed to arise first in bacterial populations colonizing upper airway environments. Here, we model this process using an experimental evolution approach. Pseudomonas aeruginosa PAO1, which is not airway adapted, was serially passaged, separately, in media chemically reflective of upper or lower airway environments. To explore whether the CF environment selects for unique traits, we separately passaged PAO1 in airway-mimicking media with or without CF-specific factors. Our findings demonstrated that all airway environments-sinus and lungs, under CF and non-CF conditions-selected for loss of twitching motility, increased resistance to multiple antibiotic classes, and a hyper-biofilm phenotype. These traits conferred increased airway colonization potential in an in vivo model. CF-like conditions exerted stronger selective pressures, leading to emergence of more pronounced phenotypes. Loss of twitching was associated with mutations in type IV pili genes. Type IV pili mediate surface attachment, twitching, and induction of cAMP signalling. We additionally identified multiple evolutionary routes to increased biofilm formation involving regulation of cyclic-di-GMP signalling. These included the loss of function mutations in bifA and dipA phosphodiesterase genes and activating mutations in the siaA phosphatase. These data highlight that airway environments select for traits associated with sessile lifestyles and suggest upper airway niches support emergence of phenotypes that promote establishment of lung infection.
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Affiliation(s)
- Dilem Ruhluel
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Lewis Fisher
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Thomas E Barton
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Hollie Leighton
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Sumit Kumar
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
| | - Paula Amores Morillo
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Siobhan O’Brien
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, 2, Ireland
| | - Joanne L Fothergill
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, United Kingdom
| | - Daniel R Neill
- Division of Molecular Microbiology, University of Dundee, Dow Street, Dundee, United Kingdom
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5
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Mikucki A, Kahler CM. Microevolution and Its Impact on Hypervirulence, Antimicrobial Resistance, and Vaccine Escape in Neisseria meningitidis. Microorganisms 2023; 11:3005. [PMID: 38138149 PMCID: PMC10745880 DOI: 10.3390/microorganisms11123005] [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: 11/06/2023] [Revised: 12/07/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
Neisseria meningitidis is commensal of the human pharynx and occasionally invades the host, causing the life-threatening illness invasive meningococcal disease. The meningococcus is a highly diverse and adaptable organism thanks to natural competence, a propensity for recombination, and a highly repetitive genome. These mechanisms together result in a high level of antigenic variation to invade diverse human hosts and evade their innate and adaptive immune responses. This review explores the ways in which this diversity contributes to the evolutionary history and population structure of the meningococcus, with a particular focus on microevolution. It examines studies on meningococcal microevolution in the context of within-host evolution and persistent carriage; microevolution in the context of meningococcal outbreaks and epidemics; and the potential of microevolution to contribute to antimicrobial resistance and vaccine escape. A persistent theme is the idea that the process of microevolution contributes to the development of new hyperinvasive meningococcal variants. As such, microevolution in this species has significant potential to drive future public health threats in the form of hypervirulent, antibiotic-resistant, vaccine-escape variants. The implications of this on current vaccination strategies are explored.
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Affiliation(s)
- August Mikucki
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia;
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, WA 6009, Australia
| | - Charlene M. Kahler
- Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, WA 6009, Australia;
- Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, University of Western Australia, Perth, WA 6009, Australia
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6
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On YY, Figueroa W, Fan C, Ho PM, Bényei ÉB, Weimann A, Ruis C, Floto AR, Welch M. Impact of transient acquired hypermutability on the inter- and intra-species competitiveness of Pseudomonas aeruginosa. THE ISME JOURNAL 2023; 17:1931-1939. [PMID: 37666975 PMCID: PMC10579334 DOI: 10.1038/s41396-023-01503-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/06/2023]
Abstract
Once acquired, hypermutation is unrelenting, and in the long-term, leads to impaired fitness due to its cumulative impact on the genome. This raises the question of why hypermutators arise so frequently in microbial ecosystems. In this work, we explore this problem by examining how the transient acquisition of hypermutability affects inter- and intra-species competitiveness, and the response to environmental insults such as antibiotic challenge. We do this by engineering Pseudomonas aeruginosa to allow the expression of an important mismatch repair gene, mutS, to be experimentally controlled over a wide dynamic range. We show that high levels of mutS expression induce genomic stasis (hypomutation), whereas lower levels of induction lead to progressively higher rates of mutation. Whole-genome sequence analyses confirmed that the mutational spectrum of the inducible hypermutator is similar to the distinctive profile associated with mutS mutants obtained from the airways of people with cystic fibrosis (CF). The acquisition of hypermutability conferred a distinct temporal fitness advantage over the wild-type P. aeruginosa progenitor strain, in both the presence and the absence of an antibiotic selection pressure. However, over a similar time-scale, acquisition of hypermutability had little impact on the population dynamics of P. aeruginosa when grown in the presence of a competing species (Staphylococcus aureus). These data indicate that in the short term, acquired hypermutability primarily confers a competitive intra-species fitness advantage.
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Affiliation(s)
- Yue Yuan On
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Wendy Figueroa
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Catherine Fan
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
- Currently based at Epoch Biodesign, Oxford, UK
| | - Pok-Man Ho
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | | | - Aaron Weimann
- Heart Lung Research Institute, University of Cambridge, Cambridge, UK
- University of Cambridge Molecular Immunity Unit, MRC Laboratory of Molecular Biology, Cambridge, UK
- Cambridge Centre for AI in Medicine, University of Cambridge, Cambridge, UK
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Christopher Ruis
- Heart Lung Research Institute, University of Cambridge, Cambridge, UK
- University of Cambridge Molecular Immunity Unit, MRC Laboratory of Molecular Biology, Cambridge, UK
- Cambridge Centre for AI in Medicine, University of Cambridge, Cambridge, UK
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Andres R Floto
- Heart Lung Research Institute, University of Cambridge, Cambridge, UK
- University of Cambridge Molecular Immunity Unit, MRC Laboratory of Molecular Biology, Cambridge, UK
- Cambridge Centre for AI in Medicine, University of Cambridge, Cambridge, UK
- Cambridge Centre for Lung Infection, Royal Papworth Hospital, Cambridge, UK
- Cambridge University Hospitals Trust, Cambridge, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Martin Welch
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
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Shepherd MJ, Pierce AP, Taylor TB. Evolutionary innovation through transcription factor rewiring in microbes is shaped by levels of transcription factor activity, expression, and existing connectivity. PLoS Biol 2023; 21:e3002348. [PMID: 37871011 PMCID: PMC10621929 DOI: 10.1371/journal.pbio.3002348] [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: 05/22/2023] [Revised: 11/02/2023] [Accepted: 09/25/2023] [Indexed: 10/25/2023] Open
Abstract
The survival of a population during environmental shifts depends on whether the rate of phenotypic adaptation keeps up with the rate of changing conditions. A common way to achieve this is via change to gene regulatory network (GRN) connections-known as rewiring-that facilitate novel interactions and innovation of transcription factors. To understand the success of rapidly adapting organisms, we therefore need to determine the rules that create and constrain opportunities for GRN rewiring. Here, using an experimental microbial model system with the soil bacterium Pseudomonas fluorescens, we reveal a hierarchy among transcription factors that are rewired to rescue lost function, with alternative rewiring pathways only unmasked after the preferred pathway is eliminated. We identify 3 key properties-high activation, high expression, and preexisting low-level affinity for novel target genes-that facilitate transcription factor innovation. Ease of acquiring these properties is constrained by preexisting GRN architecture, which was overcome in our experimental system by both targeted and global network alterations. This work reveals the key properties that determine transcription factor evolvability, and as such, the evolution of GRNs.
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Affiliation(s)
- Matthew J. Shepherd
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
- Division of Evolution and Genomic Sciences, School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Aidan P. Pierce
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
| | - Tiffany B. Taylor
- Milner Centre for Evolution, Department of Life Sciences, University of Bath, Bath, United Kingdom
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Köhler T, Luscher A, Falconnet L, Resch G, McBride R, Mai QA, Simonin JL, Chanson M, Maco B, Galiotto R, Riat A, McCallin S, Chan B, van Delden C. Personalized aerosolised bacteriophage treatment of a chronic lung infection due to multidrug-resistant Pseudomonas aeruginosa. Nat Commun 2023; 14:3629. [PMID: 37369702 PMCID: PMC10300124 DOI: 10.1038/s41467-023-39370-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Bacteriophage therapy has been suggested as an alternative or complementary strategy for the treatment of multidrug resistant (MDR) bacterial infections. Here, we report the favourable clinical evolution of a 41-year-old male patient with a Kartagener syndrome complicated by a life-threatening chronic MDR Pseudomonas aeruginosa infection, who is treated successfully with iterative aerosolized phage treatments specifically directed against the patient's isolate. We follow the longitudinal evolution of both phage and bacterial loads during and after phage administration in respiratory samples. Phage titres in consecutive sputum samples indicate in patient phage replication. Phenotypic analysis and whole genome sequencing of sequential bacterial isolates reveals a clonal, but phenotypically diverse population of hypermutator strains. The MDR phenotype in the collected isolates is multifactorial and mainly due to spontaneous chromosomal mutations. All isolates recovered after phage treatment remain phage susceptible. These results demonstrate that clinically significant improvement is achievable by personalised phage therapy even in the absence of complete eradication of P. aeruginosa lung colonization.
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Affiliation(s)
- Thilo Köhler
- Service of Infectious Diseases, Geneva University Hospitals, Geneva, Switzerland.
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
| | - Alexandre Luscher
- Service of Infectious Diseases, Geneva University Hospitals, Geneva, Switzerland
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Léna Falconnet
- Service of Infectious Diseases, Geneva University Hospitals, Geneva, Switzerland
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Grégory Resch
- Center for Research and Innovation in Clinical Pharmaceutical Sciences (CRISP), Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | | | | | - Juliette L Simonin
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Marc Chanson
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Bohumil Maco
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Raphaël Galiotto
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
| | - Arnaud Riat
- Diagnostic Bacteriology Laboratory, Geneva University Hospitals, Geneva, Switzerland
| | - Shawna McCallin
- Department of Neuro-Urology Balgrist Hospital, Zurich, Switzerland
| | | | - Christian van Delden
- Service of Infectious Diseases, Geneva University Hospitals, Geneva, Switzerland
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
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Li X, Xue X, Jia J, Zou X, Guan Y, Zhu L, Wang Z. Nonsteroidal anti-inflammatory drug diclofenac accelerates the emergence of antibiotic resistance via mutagenesis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 326:121457. [PMID: 36958653 DOI: 10.1016/j.envpol.2023.121457] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 06/18/2023]
Abstract
Overuse of antimicrobial agents are generally considered to be a key factor in the occurrence of antibiotic resistance bacteria (ARB). Nevertheless, it is unclear whether ARB can be induced by non-antibiotic chemicals such as nonsteroidal anti-inflammatory drug (NSAID). Thus, the objective of this study is to investigate whether NSAID diclofenac (DCF) promote the emergence of antibiotic resistance in Escherichia coli K12 MG1655. Our results suggested that DCF induced the occurrence of ARB which showed hereditary stability of resistance. Meanwhile, gene variation was identified on chromosome of the ARB, and DCF can cause bacterial oxidative stress and SOS response. Subsequently, transcriptional levels of antioxidant (soxS, sodA, sodC, gor, katG, ahpF) and SOS (recA, lexA, uvrA, uvrB, ruvA, ruvB, dinB, umuC, polB) system-related genes were enhanced. However, the expression of related genes cannot be increased in high-dosage treatment compared with low-dosage samples because of cytotoxicity and cellular damage. Simultaneously, high-dosage DCF decreased the mutation frequency but enhanced the resistance of mutants. Our findings expand our knowledge of the promoting effect on the emergence of ARB caused by DCF. More attention and regulations should be given to these potential ecological and health risks for widespread DCF.
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Affiliation(s)
- Xiangju Li
- Department of Aquaculture, College of Animal Science and Technology, Northwest A&F University, Xinong Road 22, Yangling, Shaanxi, 712100, China
| | - Xue Xue
- Department of Aquaculture, College of Animal Science and Technology, Northwest A&F University, Xinong Road 22, Yangling, Shaanxi, 712100, China
| | - Jia Jia
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China
| | - Xiaocui Zou
- Department of Aquaculture, College of Animal Science and Technology, Northwest A&F University, Xinong Road 22, Yangling, Shaanxi, 712100, China
| | - Yongjing Guan
- College of Marine Science, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Long Zhu
- College of Marine Science and Fisheries, Jiangsu Ocean University, Lianyungang, Jiangsu, 222005, China
| | - Zaizhao Wang
- Department of Aquaculture, College of Animal Science and Technology, Northwest A&F University, Xinong Road 22, Yangling, Shaanxi, 712100, China.
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10
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Cho C, Lee D, Jeong D, Kim S, Kim MK, Srinivasan S. Characterization of radiation-resistance mechanism in Spirosoma montaniterrae DY10 T in terms of transcriptional regulatory system. Sci Rep 2023; 13:4739. [PMID: 36959250 PMCID: PMC10036542 DOI: 10.1038/s41598-023-31509-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/13/2023] [Indexed: 03/25/2023] Open
Abstract
To respond to the external environmental changes for survival, bacteria regulates expression of a number of genes including transcription factors (TFs). To characterize complex biological phenomena, a biological system-level approach is necessary. Here we utilized six computational biology methods to infer regulatory network and to characterize underlying biologically mechanisms relevant to radiation-resistance. In particular, we inferred gene regulatory network (GRN) and operons of radiation-resistance bacterium Spirosoma montaniterrae DY10[Formula: see text] and identified the major regulators for radiation-resistance. Our results showed that DNA repair and reactive oxygen species (ROS) scavenging mechanisms are key processes and Crp/Fnr family transcriptional regulator works as a master regulatory TF in early response to radiation.
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Affiliation(s)
- Changyun Cho
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dohoon Lee
- Bioinformatics Institute, Seoul National University, Seoul, 08826, Republic of Korea
- BK21 FOUR Intelligence Computing, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dabin Jeong
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sun Kim
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
- Department of Computer Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Myung Kyum Kim
- Department of Bio & Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Republic of Korea.
| | - Sathiyaraj Srinivasan
- Department of Bio & Environmental Technology, College of Natural Science, Seoul Women's University, Seoul, 01797, Republic of Korea.
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11
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Exposure of Pseudomonas aeruginosa to Cinnamaldehyde Selects Multidrug Resistant Mutants. Antibiotics (Basel) 2022; 11:antibiotics11121790. [PMID: 36551447 PMCID: PMC9774640 DOI: 10.3390/antibiotics11121790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/07/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Cinnamaldehyde (CNA), the main component of cinnamon essential oil, is one of the most active plant compounds against nosocomial pathogen Pseudomonas aeruginosa. Exposure of wild-type strain PA14 (MIC 700 µg/mL) for 5 to 10 days to fixed (900 µg/mL) or increasing (from 900 to 1400 µg/mL) concentrations of this natural antibacterial resulted in emergence of resistant mutants CNA-A1 to A3, and CNA-B1 to B7, respectively. Genome sequencing experiments showed that each of CNA-A1 to A3 mutants differed from PA14 by one SNP, and a slight increase in CNA resistance level (from 700 to 900 µg/mL). By comparison, mutants B1 to B7 were more resistant (up to 1100 µg/mL); each of them harbored multiple SNPs (from 24 to 39) likely as a consequence of alteration of DNA mismatch repair gene mutS. Of the ten mutants selected, eight contained mutations in gene nalC, which indirectly downregulates expression of the operon that codes for multidrug efflux system MexAB-OprM, and showed increased resistance (up to 16-fold versus PA14) to antibiotic molecules exported by the pump, including ß-lactams and fluoroquinolones. Of the six mutants with the highest CNA resistance, five were no longer motile because of alteration of genes flgJ, fliE and/or pilJ genes. Altogether, our data show that P. aeruginosa is able to adapt to strong electrophilic molecules such as CNA by upregulating its intrinsic efflux pump MexAB-OprM, and through less well-characterized pleiotropic changes. Whether multidrug-resistant mutants can emerge in patients using cinnamon essential oil as self-medication needs to be assessed further.
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12
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Planet PJ. Adaptation and Evolution of Pathogens in the Cystic Fibrosis Lung. J Pediatric Infect Dis Soc 2022; 11:S23-S31. [PMID: 36069898 PMCID: PMC9451014 DOI: 10.1093/jpids/piac073] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023]
Abstract
As opposed to acute respiratory infections, the persistent bacterial infections of the lung that characterize cystic fibrosis (CF) provide ample time for bacteria to evolve and adapt. The process of adaptation is recorded in mutations that accumulate over time in the genomes of the infecting bacteria. Some of these mutations lead to obvious phenotypic differences such as antibiotic resistance or the well-known mucoid phenotype of Pseudomonas aeruginosa. Other mutations may be just as important but harder to detect such as increased mutation rates, cell surface changes, and shifts in metabolism and nutrient acquisition. Remarkably, many of the adaptations occur again and again in different patients, signaling that bacteria are adapting to solve specific challenges in the CF respiratory tract. This parallel evolution even extends across distinct bacterial species. This review addresses the bacterial systems that are known to change in long-term CF infections with a special emphasis on cross-species comparisons. Consideration is given to how adaptation may impact health in CF, and the possible evolutionary mechanisms that lead to the repeated parallel adaptations.
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Affiliation(s)
- Paul J Planet
- Corresponding Author: Paul J. Planet, MD, PhD, 3615 Civic Center Blvd, Philadelphia, PA 19104. E-mail:
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13
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MutS recognition of mismatches within primed DNA replication intermediates. DNA Repair (Amst) 2022; 119:103392. [PMID: 36095926 DOI: 10.1016/j.dnarep.2022.103392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 08/23/2022] [Accepted: 08/25/2022] [Indexed: 11/24/2022]
Abstract
MutS initiates mismatch repair by recognizing mismatches in newly replicated DNA. Specific interactions between MutS and mismatches within double-stranded DNA promote ADP-ATP exchange and a conformational change into a sliding clamp. Here, we demonstrated that MutS from Pseudomonas aeruginosa associates with primed DNA replication intermediates. The predicted structure of this MutS-DNA complex revealed a new DNA binding site, in which Asn 279 and Arg 272 appeared to directly interact with the 3'-OH terminus of primed DNA. Mutation of these residues resulted in a noticeable defect in the interaction of MutS with primed DNA substrates. Remarkably, MutS interaction with a mismatch within primed DNA induced a compaction of the protein structure and impaired the formation of an ATP-bound sliding clamp. Our findings reveal a novel DNA binding mode, conformational change and intramolecular signaling for MutS recognition of mismatches within primed DNA structures.
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14
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Hall KM, Pursell ZF, Morici LA. The role of the Pseudomonas aeruginosa hypermutator phenotype on the shift from acute to chronic virulence during respiratory infection. Front Cell Infect Microbiol 2022; 12:943346. [PMID: 35937684 PMCID: PMC9355025 DOI: 10.3389/fcimb.2022.943346] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/30/2022] [Indexed: 11/13/2022] Open
Abstract
Chronic respiratory infection (CRI) with Pseudomonas aeruginosa (Pa) presents many unique challenges that complicate treatment. One notable challenge is the hypermutator phenotype which is present in up to 60% of sampled CRI patient isolates. Hypermutation can be caused by deactivating mutations in DNA mismatch repair (MMR) genes including mutS, mutL, and uvrD. In vitro and in vivo studies have demonstrated hypermutator strains to be less virulent than wild-type Pa. However, patients colonized with hypermutators display poorer lung function and a higher incidence of treatment failure. Hypermutation and MMR-deficiency create increased genetic diversity and population heterogeneity due to elevated mutation rates. MMR-deficient strains demonstrate higher rates of mucoidy, a hallmark virulence determinant of Pa during CRI in cystic fibrosis patients. The mucoid phenotype results from simple sequence repeat mutations in the mucA gene made in the absence of functional MMR. Mutations in Pa are further increased in the absence of MMR, leading to microcolony biofilm formation, further lineage diversification, and population heterogeneity which enhance bacterial persistence and host immune evasion. Hypermutation facilitates the adaptation to the lung microenvironment, enabling survival among nutritional complexity and microaerobic or anaerobic conditions. Mutations in key acute-to-chronic virulence “switch” genes, such as retS, bfmS, and ampR, are also catalyzed by hypermutation. Consequently, strong positive selection for many loss-of-function pathoadaptive mutations is seen in hypermutators and enriched in genes such as lasR. This results in the characteristic loss of Pa acute infection virulence factors, including quorum sensing, flagellar motility, and type III secretion. Further study of the role of hypermutation on Pa chronic infection is needed to better inform treatment regimens against CRI with hypermutator strains.
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Affiliation(s)
- Kalen M. Hall
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, United States
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Zachary F. Pursell
- Department of Biochemistry and Molecular Biology, Tulane University School of Medicine, New Orleans, LA, United States
| | - Lisa A. Morici
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, United States
- *Correspondence: Lisa A. Morici,
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15
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Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that usually causes difficult-to-treat infections due to its low intrinsic antibiotic susceptibility and outstanding capacity for becoming resistant to antibiotics. In addition, it has a remarkable metabolic versatility, being able to grow in different habitats, from natural niches to different and changing inpatient environments. Study of the environmental conditions that shape genetic and phenotypic changes of P. aeruginosa toward antibiotic resistance supposes a novelty, since experimental evolution assays are usually performed with well-defined antibiotics in regular laboratory growth media. Therefore, in this work we address the extent to which the nutrients’ availability may constrain the evolution of antibiotic resistance. We determined that P. aeruginosa genetic trajectories toward resistance to tobramycin, ceftazidime, and ceftazidime-avibactam are different when evolving in laboratory rich medium, urine, or synthetic sputum. Furthermore, our study, linking genotype with phenotype, showed a clear impact of each analyzed environment on both the fitness and resistance level associated with particular resistance mutations. This indicates that the phenotype associated with specific resistance mutations is variable and dependent on the bacterial metabolic state in each particular habitat. Our results support that the design of evolution-based strategies to tackle P. aeruginosa infections should be based on robust patterns of evolution identified within each particular infection and body location. IMPORTANCE Predicting evolution toward antibiotic resistance (AR) and its associated trade-offs, such as collateral sensitivity, is important to design evolution-based strategies to tackle AR. However, the effect of nutrients' availability on such evolution, particularly those that can be found under in vivo infection conditions, has been barely addressed. We analyzed the evolutionary patterns of P. aeruginosa in the presence of antibiotics in different media, including urine and synthetic sputum, whose compositions are similar to the ones in infections, finding that AR evolution differs, depending on growth conditions. Furthermore, the representative mutants isolated under each condition tested render different AR levels and fitness costs, depending on nutrients’ availability, supporting the idea that environmental constraints shape the phenotypes associated with specific AR mutations. Consequently, the selection of AR mutations that render similar phenotypes is environment dependent. The analysis of evolution patterns toward AR requires studying growth conditions mimicking those that bacteria face during in vivo evolution.
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16
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Madden DE, Olagoke O, Baird T, Neill J, Ramsay KA, Fraser TA, Bell SC, Sarovich DS, Price EP. Express Yourself: Quantitative Real-Time PCR Assays for Rapid Chromosomal Antimicrobial Resistance Detection in Pseudomonas aeruginosa. Antimicrob Agents Chemother 2022; 66:e0020422. [PMID: 35467369 PMCID: PMC9112894 DOI: 10.1128/aac.00204-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 03/31/2022] [Indexed: 01/03/2023] Open
Abstract
The rise of antimicrobial-resistant (AMR) bacteria is a global health emergency. One critical facet of tackling this epidemic is more rapid AMR diagnosis in serious multidrug-resistant pathogens like Pseudomonas aeruginosa. Here, we designed and then validated two multiplex quantitative real-time PCR (qPCR) assays to simultaneously detect differential expression of the resistance-nodulation-division efflux pumps MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY-OprM, the AmpC β-lactamase, and the porin OprD, which are commonly associated with chromosomally encoded AMR. Next, qPCRs were tested on 15 sputa from 11 participants with P. aeruginosa respiratory infections to determine AMR profiles in vivo. We confirmed multiplex qPCR testing feasibility directly on sputa, representing a key advancement in in vivo AMR diagnosis. Notably, comparison of sputa with their derived isolates grown in Luria-Bertani broth (±2.5% NaCl) or a 5-antibiotic cocktail showed marked expression differences, illustrating the difficulty in replicating in vivo expression profiles in vitro. Cystic fibrosis sputa showed significantly reduced mexE and mexY expression compared with chronic obstructive pulmonary disease sputa, despite harboring fluoroquinolone- and aminoglycoside-resistant strains, indicating that these loci do not contribute to AMR in vivo. oprD was also significantly downregulated in cystic fibrosis sputa, even in the absence of contemporaneous carbapenem use, suggesting a common adaptive trait in chronic infections that may affect carbapenem efficacy. Sputum ampC expression was highest in participants receiving carbapenems (6.7 to 15×), some of whom were simultaneously receiving cephalosporins, the latter of which would be rendered ineffective by the upregulated ampC. Our qPCR assays provide valuable insights into the P. aeruginosa resistome, and their use on clinical specimens will permit timely treatment alterations that will improve patient outcomes and antimicrobial stewardship measures.
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Affiliation(s)
- Danielle E. Madden
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Olusola Olagoke
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Timothy Baird
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
- Respiratory Department, Sunshine Coast University Hospital, Birtinya, Queensland, Australia
| | - Jane Neill
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
- Respiratory Department, Sunshine Coast University Hospital, Birtinya, Queensland, Australia
| | - Kay A. Ramsay
- Child Health Research Centre, The University of Queensland, South Brisbane, Queensland, Australia
| | - Tamieka A. Fraser
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Scott C. Bell
- Child Health Research Centre, The University of Queensland, South Brisbane, Queensland, Australia
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, Queensland, Australia
- Translational Research Institute, Woolloongabba, Queensland, Australia
| | - Derek S. Sarovich
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
| | - Erin P. Price
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
- Sunshine Coast Health Institute, Birtinya, Queensland, Australia
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17
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Kaushik S, Yadav J, Das S, Karthikeyan D, Chug R, Jyoti A, Srivastava VK, Jain A, Kumar S, Sharma V. Identification of Protein Drug Targets of Biofilm Formation and Quorum
Sensing in Multidrug Resistant Enterococcus faecalis. Curr Protein Pept Sci 2022; 23:248-263. [DOI: 10.2174/1389203723666220526155644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/16/2022] [Accepted: 04/06/2022] [Indexed: 11/22/2022]
Abstract
Abstract:
Enterococcus faecalis (E. faecalis) is an opportunistic multidrug-resistant (MDR) pathogen
found in the guts of humans and farmed animals. Due to the occurrence of (MDR) strain there is an
urgent need to look for an alternative treatment approach. E. faecalis is a Gram-positive bacterium,
which is among the most prevalent multidrug resistant hospital pathogens. Its ability to develop quorum
sensing (QS) mediated biofilm formation further exacerbates the pathogenicity and triggers lifethreatening
infections. Therefore, developing a suitable remedy for curing E. faecalis mediated enterococcal
infections is an arduous task. Several putative virulence factors and proteins are involved in the
development of biofilms in E. faecalis. Such proteins often play important roles in virulence, disease,
and colonization by pathogens. The elucidation of the structure-function relationship of such protein
drug targets and the interacting compounds could provide an attractive paradigm towards developing
structure-based drugs against E. faecalis. This review provides a comprehensive overview of the current
status, enigmas that warrant further studies, and the prospects toward alleviating the antibiotic resistance
in E. faecalis. Specifically, the role of biofilm and quorum sensing (QS) in the emergence of
MDR strains had been elaborated along with the importance of the protein drug targets involved in both
the processes.
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Affiliation(s)
- Sanket Kaushik
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Jyoti Yadav
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Satyajeet Das
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
- Structural Biology Lab, CSIR-Institute of Microbial Technology, Chandigarh, India
| | | | - Ravneet Chug
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Anupam Jyoti
- Department of Biotechnology, University Institute of Biotechnology,
Chandigarh University, Chandigarh, India
| | | | - Ajay Jain
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
| | - Sanjit Kumar
- Centre for Bioseparation Technology, VIT
University, Vellore-632014, Tamil Nadu, India
| | - Vinay Sharma
- Amity Institute of Biotechnology, Amity University Rajasthan, Jaipur, India
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18
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Tümmler B. What Makes Pseudomonas aeruginosa a Pathogen? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1386:283-301. [DOI: 10.1007/978-3-031-08491-1_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Functional analysis of H +-pumping membrane-bound pyrophosphatase, ADP-glucose synthase, and pyruvate phosphate dikinase as pyrophosphate sources in Clostridium thermocellum. Appl Environ Microbiol 2021; 88:e0185721. [PMID: 34936842 PMCID: PMC8863071 DOI: 10.1128/aem.01857-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The atypical glycolysis of Clostridium thermocellum is characterized by the use of pyrophosphate (PPi) as phosphoryl donor for phosphofructokinase (Pfk) and pyruvate phosphate dikinase (Ppdk) reactions. Previously, biosynthetic PPi was calculated to be stoichiometrically insufficient to drive glycolysis. This study investigates the role of a H+-pumping membrane-bound pyrophosphatase, glycogen cycling, a predicted Ppdk-malate shunt cycle and acetate cycling in generating PPi. Knockout studies and enzyme assays confirmed that clo1313_0823 encodes a membrane-bound pyrophosphatase. Additionally, clo1313_0717-0718 was confirmed to encode ADP-glucose synthase by knockouts, glycogen measurements in C. thermocellum and heterologous expression in E. coli. Unexpectedly, individually-targeted gene deletions of the four putative PPi sources did not have a significant phenotypic effect. Although combinatorial deletion of all four putative PPi sources reduced the growth rate by 22% (0.30±0.01 h-1) and the biomass yield by 38% (0.18±0.00 gbiomass gsubstrate-1), this change was much smaller than what would be expected for stoichiometrically essential PPi-supplying mechanisms. Growth-arrested cells of the quadruple knockout readily fermented cellobiose indicating that the unknown PPi-supplying mechanisms are independent of biosynthesis. An alternative hypothesis that ATP-dependent Pfk activity circumvents a need for PPi altogether, was falsified by enzyme assays, heterologous expression of candidate genes and whole-genome sequencing. As a secondary outcome, enzymatic assays confirmed functional annotation of clo1313_1832 as ATP- and GTP-dependent fructokinase. These results indicate that the four investigated PPi sources individually and combined play no significant PPi-supplying role and the true source(s) of PPi, or alternative phosphorylating mechanisms, that drive glycolysis in C. thermocellum remain(s) elusive. IMPORTANCE Increased understanding of the central metabolism of C. thermocellum is important from a fundamental as well as from a sustainability and industrial perspective. In addition to showing that H+-pumping membrane-bound PPase, glycogen cycling, a Ppdk-malate shunt cycle, and acetate cycling are not significant sources of PPi supply, this study adds functional annotation of four genes and availability of an updated PPi stoichiometry from biosynthesis to the scientific domain. Together, this aids future metabolic engineering attempts aimed to improve C. thermocellum as a cell factory for sustainable and efficient production of ethanol from lignocellulosic material through consolidated bioprocessing with minimal pretreatment. Getting closer to elucidating the elusive source of PPi, or alternative phosphorylating mechanisms, for the atypical glycolysis is itself of fundamental importance. Additionally, the findings of this study directly contribute to investigations into trade-offs between thermodynamic driving force versus energy yield of PPi- and ATP-dependent glycolysis.
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20
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On YY, Welch M. The methylation-independent mismatch repair machinery in Pseudomonas aeruginosa. MICROBIOLOGY (READING, ENGLAND) 2021; 167. [PMID: 34882086 PMCID: PMC8744996 DOI: 10.1099/mic.0.001120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Over the last 70 years, we've all gotten used to an Escherichia coli-centric view of the microbial world. However, genomics, as well as the development of improved tools for genetic manipulation in other species, is showing us that other bugs do things differently, and that we cannot simply extrapolate from E. coli to everything else. A particularly good example of this is encountered when considering the mechanism(s) involved in DNA mismatch repair by the opportunistic human pathogen, Pseudomonas aeruginosa (PA). This is a particularly relevant phenotype to examine in PA, since defects in the mismatch repair (MMR) machinery often give rise to the property of hypermutability. This, in turn, is linked with the vertical acquisition of important pathoadaptive traits in the organism, such as antimicrobial resistance. But it turns out that PA lacks some key genes associated with MMR in E. coli, and a closer inspection of what is known (or can be inferred) about the MMR enzymology reveals profound differences compared with other, well-characterized organisms. Here, we review these differences and comment on their biological implications.
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Affiliation(s)
- Yue Yuan On
- Department of Biochemistry, Hopkins Building, Tennis Court Road, Downing Site, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Martin Welch
- Department of Biochemistry, Hopkins Building, Tennis Court Road, Downing Site, University of Cambridge, Cambridge, CB2 1QW, UK
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21
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Figueiredo ART, Wagner A, Kümmerli R. Ecology drives the evolution of diverse social strategies in Pseudomonas aeruginosa. Mol Ecol 2021; 30:5214-5228. [PMID: 34390514 PMCID: PMC9291133 DOI: 10.1111/mec.16119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/03/2021] [Accepted: 07/28/2021] [Indexed: 11/27/2022]
Abstract
Bacteria often cooperate by secreting molecules that can be shared as public goods between cells. Because the production of public goods is subject to cheating by mutants that exploit the good without contributing to it, there has been great interest in elucidating the evolutionary forces that maintain cooperation. However, little is known about how bacterial cooperation evolves under conditions where cheating is unlikely to be of importance. Here we use experimental evolution to follow changes in the production of a model public good, the iron‐scavenging siderophore pyoverdine, of the bacterium Pseudomonas aeruginosa. After 1200 generations of evolution in nine different environments, we observed that cheaters only reached high frequency in liquid medium with low iron availability. Conversely, when adding iron to reduce the cost of producing pyoverdine, we observed selection for pyoverdine hyperproducers. Similarly, hyperproducers also spread in populations evolved in highly viscous media, where relatedness between interacting individuals is increased. Whole‐genome sequencing of evolved clones revealed that hyperproduction is associated with mutations involving genes encoding quorum‐sensing communication systems, while cheater clones had mutations in the iron‐starvation sigma factor or in pyoverdine biosynthesis genes. Our findings demonstrate that bacterial social traits can evolve rapidly in divergent directions, with particularly strong selection for increased levels of cooperation occurring in environments where individual dispersal is reduced, as predicted by social evolution theory. Moreover, we establish a regulatory link between pyoverdine production and quorum‐sensing, showing that increased cooperation with respect to one trait (pyoverdine) can be associated with the loss (quorum‐sensing) of another social trait.
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Affiliation(s)
- Alexandre R T Figueiredo
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Andreas Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland.,The Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
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22
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Strand discrimination in DNA mismatch repair. DNA Repair (Amst) 2021; 105:103161. [PMID: 34171627 DOI: 10.1016/j.dnarep.2021.103161] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/24/2022]
Abstract
DNA mismatch repair (MMR) corrects non-Watson-Crick basepairs generated by replication errors, recombination intermediates, and some forms of chemical damage to DNA. In MutS and MutL homolog-dependent MMR, damaged bases do not identify the error-containing daughter strand that must be excised and resynthesized. In organisms like Escherichia coli that use methyl-directed MMR, transient undermethylation identifies the daughter strand. For other organisms, growing in vitro and in vivo evidence suggest that strand discrimination is mediated by DNA replication-associated daughter strand nicks that direct asymmetric loading of the replicative clamp (the β-clamp in bacteria and the proliferating cell nuclear antigen, PCNA, in eukaryotes). Structural modeling suggests that replicative clamps mediate strand specificity either through the ability of MutL homologs to recognize the fixed orientation of the daughter strand relative to one face of the replicative clamps or through parental strand-specific diffusion of replicative clamps on DNA, which places the daughter strand in the MutL homolog endonuclease active site. Finally, identification of bacteria that appear to lack strand discrimination mediated by a replicative clamp and a pre-existing nick suggest that other strand discrimination mechanisms exist or that these organisms perform MMR by generating a double-stranded DNA break intermediate, which may be analogous to NucS-mediated MMR.
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23
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Almeida MM, Freitas MT, Folescu TW, Firmida MC, Carvalho-Assef APD, Marques EA, Leão RS. Carbapenem-Resistant Pseudomonas aeruginosa in Chronic Lung Infection: Current Resistance Profile and Hypermutability in Patients with Cystic Fibrosis. Curr Microbiol 2021; 78:696-704. [PMID: 33404752 DOI: 10.1007/s00284-020-02337-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 12/14/2020] [Indexed: 11/29/2022]
Abstract
Pseudomonas aeruginosa is associated with chronic and progressive lung disease and is closely related to increased morbidity and mortality in cystic fibrosis (CF) patients. Hypermutable (HPM) P. aeruginosa isolates have been described in these patients and are usually associated with antibiotic resistance. This study aimed to investigate the occurrence of carbapenem resistance and hypermutable phenotype in 179 P. aeruginosa isolates from 8 chronically CF patients assisted at two reference centers in Rio de Janeiro, Brazil. Using disk diffusion test, non-susceptible (NS) rates higher than 40% were observed for imipenem, amikacin, and gentamicin. A total of 79 isolates (44.1%), 71 (39.6%), and 8 (4.4%) were classified as carbapenem-resistant (CR resistance to at least one carbapenem), multidrug-resistant (MDR), and extensively drug-resistant (XDR), respectively. Minimal inhibitory concentration was determined for 79 CR P. aeruginosa and showed the following variations: 4 and 128 μg/mL to imipenem, 4 and 64 µg/mL to meropenem, and 4 and ≥ 32 µg/mL to doripenem. We have found only four (2.23%) HPM isolates from 4 patients. Analyzing the genetic relationship among the HPM isolates, 3 pulsed-field gel electrophoresis/pulsotypes (D, M, and J) were observed. Only M pulsotype was recovered from two patients in different years. Polymerase chain reaction screening for blaGES, blaIMP, blaKPC, blaNDM, blaOXA-48, blaSPM, and blaVIM genes was performed for all CR isolates and none of them were positive. Our results demonstrate a high occurrence of CR and MDR P. aeruginosa of CF patients follow-up in both centers studied, while the presence of HPM is still unusual.
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Affiliation(s)
- Mila M Almeida
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Meyvianne T Freitas
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tania W Folescu
- Instituto Nacional de Saúde da Mulher, Criança e do Adolescente Fernandes Figueira, Centro de Referência para Crianças e Adolescentes com Fibrose Cística - Ministério da Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Monica C Firmida
- Departamento de Doenças do Tórax, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ana Paula D'A Carvalho-Assef
- Laboratório de Pesquisa em Infecção Hospitalar, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Elizabeth A Marques
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Robson S Leão
- Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
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Chakravarty S, Ramos-Hegazy L, Gasparovic A, Anderson GG. DNA alternate polymerase PolB mediates inhibition of type III secretion in Pseudomonas aeruginosa. Microbes Infect 2020; 23:104777. [PMID: 33276123 DOI: 10.1016/j.micinf.2020.11.004] [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: 07/02/2020] [Revised: 11/10/2020] [Accepted: 11/13/2020] [Indexed: 10/22/2022]
Abstract
Opportunistic pathogen Pseudomonas aeruginosa uses a variety of virulence factors to cause acute and chronic infections. We previously found that alternate DNA polymerase gene polB inhibits P. aeruginosa pyocyanin production. We investigated whether polB also affects T3SS expression. polB overexpression significantly reduced T3SS transcription and repressed translation of the master T3SS regulator ExsA, while not affecting exsA mRNA transcript abundance. Further, polB does not act through previously described genetic pathways that post-transcriptionally regulate ExsA. Our results show a novel T3SS regulatory component which may lead to development of future drugs to target this mechanism.
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Affiliation(s)
- Shubham Chakravarty
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
| | - Layla Ramos-Hegazy
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
| | - Abigail Gasparovic
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
| | - Gregory G Anderson
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA.
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25
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Khan M, Stapleton F, Summers S, Rice SA, Willcox MDP. Antibiotic Resistance Characteristics of Pseudomonas aeruginosa Isolated from Keratitis in Australia and India. Antibiotics (Basel) 2020; 9:antibiotics9090600. [PMID: 32937932 PMCID: PMC7559795 DOI: 10.3390/antibiotics9090600] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 02/07/2023] Open
Abstract
This study investigated genomic differences in Australian and Indian Pseudomonas aeruginosa isolates from keratitis (infection of the cornea). Overall, the Indian isolates were resistant to more antibiotics, with some of those isolates being multi-drug resistant. Acquired genes were related to resistance to fluoroquinolones, aminoglycosides, beta-lactams, macrolides, sulphonamides, and tetracycline and were more frequent in Indian (96%) than in Australian (35%) isolates (p = 0.02). Indian isolates had large numbers of gene variations (median 50,006, IQR = 26,967-50,600) compared to Australian isolates (median 26,317, IQR = 25,681-33,780). There were a larger number of mutations in the mutL and uvrD genes associated with the mismatch repair (MMR) system in Indian isolates, which may result in strains losing their efficacy for DNA repair. The number of gene variations were greater in isolates carrying MMR system genes or exoU. In the phylogenetic division, the number of core genes were similar in both groups, but Indian isolates had larger numbers of pan genes (median 6518, IQR = 6040-6935). Clones related to three different sequence types-ST308, ST316, and ST491-were found among Indian isolates. Only one clone, ST233, containing two strains was present in Australian isolates. The most striking differences between Australian and Indian isolates were carriage of exoU (that encodes a cytolytic phospholipase) in Indian isolates and exoS (that encodes for GTPase activator activity) in Australian isolates, large number of acquired resistance genes, greater changes to MMR genes, and a larger pan genome as well as increased overall genetic variation in the Indian isolates.
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Affiliation(s)
- Mahjabeen Khan
- School of Optometry and Vision Science, UNSW, Sydney, NSW 2052, Australia; (M.K.); (F.S.)
| | - Fiona Stapleton
- School of Optometry and Vision Science, UNSW, Sydney, NSW 2052, Australia; (M.K.); (F.S.)
| | - Stephen Summers
- The Singapore Centre for Environment Life Sciences Engineering (SCELSE), The School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; (S.S.); (S.A.R.)
| | - Scott A. Rice
- The Singapore Centre for Environment Life Sciences Engineering (SCELSE), The School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore; (S.S.); (S.A.R.)
- The ithree Institute, The University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Mark D. P. Willcox
- School of Optometry and Vision Science, UNSW, Sydney, NSW 2052, Australia; (M.K.); (F.S.)
- Correspondence: ; Tel.: +61-2-9385-4164
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26
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Martak D, Meunier A, Sauget M, Cholley P, Thouverez M, Bertrand X, Valot B, Hocquet D. Comparison of pulsed-field gel electrophoresis and whole-genome-sequencing-based typing confirms the accuracy of pulsed-field gel electrophoresis for the investigation of local Pseudomonas aeruginosa outbreaks. J Hosp Infect 2020; 105:643-647. [DOI: 10.1016/j.jhin.2020.06.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 06/08/2020] [Indexed: 12/17/2022]
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27
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Sheng H, Huang J, Han Z, Liu M, Lü Z, Zhang Q, Zhang J, Yang J, Cui S, Yang B. Genes and Proteomes Associated With Increased Mutation Frequency and Multidrug Resistance of Naturally Occurring Mismatch Repair-Deficient Salmonella Hypermutators. Front Microbiol 2020; 11:770. [PMID: 32457709 PMCID: PMC7225559 DOI: 10.3389/fmicb.2020.00770] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/31/2020] [Indexed: 11/23/2022] Open
Abstract
The emergence of antibiotic-resistant Salmonella through mutations led to mismatch repair (MMR) deficiency that represents a potential hazard to public health. Here, four representative MMR-deficient Salmonella hypermutator strains and Salmonella Typhimurium LT2 were used to comprehensively reveal the influence of MMR deficiency on antibiotic resistance among Salmonella. Our results indicated that the mutation frequency ranged from 3.39 × 10–4 to 5.46 × 10–2 in the hypermutator. Mutation sites in MutS, MutL, MutT, and UvrD of the four hypermutators were all located in the essential and core functional regions. Mutation frequency of the hypermutator was most highly correlated with the extent of mutation in MutS. Mutations in MMR genes (mutS, mutT, mutL, and uvrD) were correlated with increased mutation in antibiotic resistance genes, and the extent of antibiotic resistance was significantly correlated with the number of mutation sites in MutL and in ParC. The number of mutation sites in MMR genes and antibiotic resistance genes exhibited a significant positive correlation with the number of antibiotics resisted and with expression levels of mutS, mutT, and mutL. Compared to Salmonella Typhimurium LT2, a total of 137 differentially expressed and 110 specifically expressed proteins were identified in the four hypermutators. Functional enrichment analysis indicated that the proteins significantly overexpressed in the hypermutators primarily associated with translation and stress response. Interaction network analysis revealed that the ribosome pathway might be a critical factor for high mutation frequency and multidrug resistance in MMR-deficient Salmonella hypermutators. These results help elucidate the mutational dynamics that lead to hypermutation, antibiotic resistance, and activation of stress response pathways in Salmonella.
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Affiliation(s)
- Huanjing Sheng
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Jinling Huang
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Zhaoyu Han
- School of Pharmaceutical Sciences, Jiangnan University, Wuxi, China
| | - Mi Liu
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Zexun Lü
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Qian Zhang
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Jinlei Zhang
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Jun Yang
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
| | - Shenghui Cui
- National Institutes for Food and Drug Control, Beijing, China
| | - Baowei Yang
- College of Food Science and Engineering, Northwest A&F University, Xianyang, China
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28
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Prevalence of hypermutator isolates of Achromobacter spp. from cystic fibrosis patients. Int J Med Microbiol 2020; 310:151393. [PMID: 31969255 DOI: 10.1016/j.ijmm.2020.151393] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 10/30/2019] [Accepted: 12/04/2019] [Indexed: 01/26/2023] Open
Abstract
Bacteria colonising the lungs of cystic fibrosis (CF) patients encounter high selective pressures. Hypermutation facilitates adaptation to fluctuating environments, and hypermutator strains are frequently isolated from CF patients. We investigated the prevalence of hypermutator isolates of Achromobacter spp. among patients affiliated with the CF Centre in Aarhus, Denmark. By exposure to rifampicin, the mutation frequency was determined for 90 isolates of Achromobacter spp. cultured from 42 CF patients; 20 infections were categorised as chronic, 22 as intermittent. The genetic mechanisms of hypermutation were examined by comparing DNA repair gene sequences from hypermutator and normomutator isolates. Achromobacter spp. cultured from 11 patients were categorised as hypermutators, and this phenotype was exclusively associated with chronic infections. Isolates of the Danish epidemic strain (DES) of Achromobacter ruhlandii cultured from patients from both Danish CF centres showed elevated mutation frequencies. The hypermutator state of Achromobacter spp. was most commonly associated with nonsynonymous mutations in the DNA mismatch repair gene mutS; a single clone had developed a substitution in the S-adenosyl-L-methionine-dependent methyltransferase putatively involved in DNA repair mechanisms, but not previously linked to the hypermutator phenotype. Hypermutation is prevalent among clinical isolates of Achromobacter spp. and could be a key determinant for the extraordinary adaptation and persistence of DES.
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Hernando-Amado S, Sanz-García F, Martínez JL. Antibiotic Resistance Evolution Is Contingent on the Quorum-Sensing Response in Pseudomonas aeruginosa. Mol Biol Evol 2020; 36:2238-2251. [PMID: 31228244 DOI: 10.1093/molbev/msz144] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Different works have explored independently the evolution toward antibiotic resistance and the role of eco-adaptive mutations in the adaptation to a new habitat (as the infected host) of bacterial pathogens. However, knowledge about the connection between both processes is still limited. We address this issue by comparing the evolutionary trajectories toward antibiotic resistance of a Pseudomonas aeruginosa lasR defective mutant and its parental wild-type strain, when growing in presence of two ribosome-targeting antibiotics. Quorum-sensing lasR defective mutants are selected in P. aeruginosa populations causing chronic infections. Further, we observed they are also selected in vitro as a first adaptation for growing in culture medium. By using experimental evolution and whole-genome sequencing, we found that the evolutionary trajectories of P. aeruginosa in presence of these antibiotics are different in lasR defective and in wild-type backgrounds, both at the phenotypic and the genotypic levels. Recreation of a set of mutants in both genomic backgrounds (either wild type or lasR defective) allowed us to determine the existence of negative epistatic interactions between lasR and antibiotic resistance determinants. These epistatic interactions could lead to mutual contingency in the evolution of antibiotic resistance when P. aeruginosa colonizes a new habitat in presence of antibiotics. If lasR mutants are selected first, this would constraint antibiotic resistance evolution. Conversely, when resistance mutations (at least those studied in the present work) are selected, lasR mutants may not be selected in presence of antibiotics. These results underlie the importance of contingency and epistatic interactions in modulating antibiotic resistance evolution.
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30
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Płaczkiewicz J, Adamczyk-Popławska M, Lasek R, Bącal P, Kwiatek A. Inactivation of Genes Encoding MutL and MutS Proteins Influences Adhesion and Biofilm Formation by Neisseria gonorrhoeae. Microorganisms 2019; 7:microorganisms7120647. [PMID: 31817122 PMCID: PMC6955733 DOI: 10.3390/microorganisms7120647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/29/2019] [Accepted: 12/02/2019] [Indexed: 11/16/2022] Open
Abstract
Neisseria gonorrhoeae is an etiological agent of gonorrhea, which remains a global health problem. This bacterium possesses MutL and MutS DNA repair proteins encoded by mutL and mutS genes, whose inactivation causes a mutator phenotype. We have demonstrated the differential gene expression in N. gonorrhoeae mutL and mutS mutants using DNA microarrays. A subset of differentially expressed genes encodes proteins that can influence adhesion and biofilm formation. Compared to the wild-type strain, N. gonorrhoeae mutL and mutS mutants formed denser biofilms with increased biofilm-associated biomass on the abiotic surface. The N. gonorrhoeae mutS::km, but not the mutL mutant, was also more adherent and invasive to human epithelial cells. Further, during infection of epithelial cells with N. gonorrhoeae mutS::km, the expression of some bacterial genes encoding proteins that can influence gonococcal adhesion was changed compared with their expression in cells infected with the wild-type gonococcus, as well as of human genes' encoding receptors utilized by N. gonorrhoeae (CD46, CEACAM 1, HSPG 2). Thus, deficiency in the mutS gene resulting in increased mutation frequency in singular organisms can be beneficial in populations because these mutants can be a source of features linked to microbial fitness.
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Affiliation(s)
- Jagoda Płaczkiewicz
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; (J.P.); (M.A.-P.); (R.L.)
| | - Monika Adamczyk-Popławska
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; (J.P.); (M.A.-P.); (R.L.)
| | - Robert Lasek
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; (J.P.); (M.A.-P.); (R.L.)
| | - Pawel Bącal
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland;
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, 02-109 Warsaw, Poland
| | - Agnieszka Kwiatek
- Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland; (J.P.); (M.A.-P.); (R.L.)
- Correspondence: ; Tel.: +48-22-554-14-21
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31
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Aparicio T, Nyerges A, Nagy I, Pal C, Martínez‐García E, Lorenzo V. Mismatch repair hierarchy of
Pseudomonas putida
revealed by mutagenic ssDNA recombineering of the
pyrF
gene. Environ Microbiol 2019; 22:45-58. [DOI: 10.1111/1462-2920.14814] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 09/29/2019] [Accepted: 09/30/2019] [Indexed: 11/25/2022]
Affiliation(s)
- Tomas Aparicio
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
| | - Akos Nyerges
- Synthetic and Systems Biology UnitInstitute of Biochemistry
| | - István Nagy
- Sequencing Platform, Biological Research CentreHungarian Academy of Sciences H‐6726 Szeged
- Sequencing LaboratorySeqOmics Biotechnology Ltd. 6782 Mórahalom Hungary
| | - Csaba Pal
- Synthetic and Systems Biology UnitInstitute of Biochemistry
| | - Esteban Martínez‐García
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
| | - Víctor Lorenzo
- Systems and Synthetic Biology ProgramCentro Nacional de Biotecnología (CNB‐CSIC), Campus de Cantoblanco Madrid 28049 Spain
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32
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Khalili-Samani M, Barati M, Mirmohammadsadegh N, Amin M, Samadikuchaksaraei A. Detection of Mutations of Antimutator Gene pfpI in Pseudomonas aeruginosa Species Isolated from Burn Patients in Tehran, Iran. JOURNAL OF MEDICAL MICROBIOLOGY AND INFECTIOUS DISEASES 2019. [DOI: 10.29252/jommid.7.4.127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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33
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Blázquez J, Rodríguez-Beltrán J, Matic I. Antibiotic-Induced Genetic Variation: How It Arises and How It Can Be Prevented. Annu Rev Microbiol 2019; 72:209-230. [PMID: 30200850 DOI: 10.1146/annurev-micro-090817-062139] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
By targeting essential cellular processes, antibiotics provoke metabolic perturbations and induce stress responses and genetic variation in bacteria. Here we review current knowledge of the mechanisms by which these molecules generate genetic instability. They include production of reactive oxygen species, as well as induction of the stress response regulons, which lead to enhancement of mutation and recombination rates and modulation of horizontal gene transfer. All these phenomena influence the evolution and spread of antibiotic resistance. The use of strategies to stop or decrease the generation of resistant variants is also discussed.
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Affiliation(s)
- Jesús Blázquez
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), 28049 Madrid, Spain; .,Unidad de Enfermedades Infecciosas, Microbiologia y Medicina Preventiva, Hospital Universitario Virgen del Rocio, 41013 Seville, Spain.,Red Española de Investigacion en Patologia Infecciosa, Instituto de Salud Carlos III, 28029 Madrid, Spain
| | | | - Ivan Matic
- Faculté de Médecine Paris Descartes, INSERM 1001, CNRS, Université Paris-Descartes-Sorbonne Paris Cité, 75014 Paris, France;
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Shen M, Zhang H, Shen W, Zou Z, Lu S, Li G, He X, Agnello M, Shi W, Hu F, Le S. Pseudomonas aeruginosa MutL promotes large chromosomal deletions through non-homologous end joining to prevent bacteriophage predation. Nucleic Acids Res 2019. [PMID: 29514250 PMCID: PMC5961081 DOI: 10.1093/nar/gky160] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen with a relatively large genome, and has been shown to routinely lose genomic fragments during environmental selection. However, the underlying molecular mechanisms that promote chromosomal deletion are still poorly understood. In a recent study, we showed that by deleting a large chromosomal fragment containing two closely situated genes, hmgA and galU, P. aeruginosa was able to form ‘brown mutants’, bacteriophage (phage) resistant mutants with a brown color phenotype. In this study, we show that the brown mutants occur at a frequency of 227 ± 87 × 10−8 and contain a deletion ranging from ∼200 to ∼620 kb. By screening P. aeruginosa transposon mutants, we identified mutL gene whose mutation constrained the emergence of phage-resistant brown mutants. Moreover, the P. aeruginosa MutL (PaMutL) nicking activity can result in DNA double strand break (DSB), which is then repaired by non-homologous end joining (NHEJ), leading to chromosomal deletions. Thus, we reported a noncanonical function of PaMutL that promotes chromosomal deletions through NHEJ to prevent phage predation.
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Affiliation(s)
- Mengyu Shen
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Huidong Zhang
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China
| | - Wei Shen
- Department of Medical Laboratory, Chengdu Military General Hospital, Chengdu 610083, China
| | - Zhenyu Zou
- Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China
| | - Shuguang Lu
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Gang Li
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Xuesong He
- The Forsyth Institute, 245 First St, Cambridge, MA 02142, USA
| | - Melissa Agnello
- School of Dentistry, University of California, Los Angeles, CA 90095, USA
| | - Wenyuan Shi
- The Forsyth Institute, 245 First St, Cambridge, MA 02142, USA
| | - Fuquan Hu
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
| | - Shuai Le
- Department of Microbiology, Third Military Medical University, Chongqing 400038, China
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35
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The Essential Role of Hypermutation in Rapid Adaptation to Antibiotic Stress. Antimicrob Agents Chemother 2019; 63:AAC.00744-19. [PMID: 31036684 DOI: 10.1128/aac.00744-19] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 04/19/2019] [Indexed: 12/22/2022] Open
Abstract
A common outcome of antibiotic exposure in patients and in vitro is the evolution of a hypermutator phenotype that enables rapid adaptation by pathogens. While hypermutation is a robust mechanism for rapid adaptation, it requires trade-offs between the adaptive mutations and the more common "hitchhiker" mutations that accumulate from the increased mutation rate. Using quantitative experimental evolution, we examined the role of hypermutation in driving the adaptation of Pseudomonas aeruginosa to colistin. Metagenomic deep sequencing revealed 2,657 mutations at ≥5% frequency in 1,197 genes and 761 mutations in 29 endpoint isolates. By combining genomic information, phylogenetic analyses, and statistical tests, we showed that evolutionary trajectories leading to resistance could be reliably discerned. In addition to known alleles such as pmrB, hypermutation allowed identification of additional adaptive alleles with epistatic relationships. Although hypermutation provided a short-term fitness benefit, it was detrimental to overall fitness. Alarmingly, a small fraction of the colistin-adapted population remained colistin susceptible and escaped hypermutation. In a clinical population, such cells could play a role in reestablishing infection upon withdrawal of colistin. We present here a framework for evaluating the complex evolutionary trajectories of hypermutators that applies to both current and emerging pathogen populations.
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36
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Fernández‐Cabezón L, Cros A, Nikel PI. Evolutionary Approaches for Engineering Industrially Relevant Phenotypes in Bacterial Cell Factories. Biotechnol J 2019; 14:e1800439. [DOI: 10.1002/biot.201800439] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 04/08/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Lorena Fernández‐Cabezón
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Antonin Cros
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
| | - Pablo I. Nikel
- The Novo Nordisk Foundation Center for BiosustainabilityTechnical University of Denmark 2800 Kongens Lyngby Denmark
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37
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Chevallereau A, Meaden S, van Houte S, Westra ER, Rollie C. The effect of bacterial mutation rate on the evolution of CRISPR-Cas adaptive immunity. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180094. [PMID: 30905293 PMCID: PMC6452272 DOI: 10.1098/rstb.2018.0094] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2018] [Indexed: 01/07/2023] Open
Abstract
CRISPR-Cas immune systems are present in around half of bacterial genomes. Given the specificity and adaptability of this immune mechanism, it is perhaps surprising that they are not more widespread. Recent insights into the requirement for specific host factors for the function of some CRISPR-Cas subtypes, as well as the negative epistasis between CRISPR-Cas and other host genes, have shed light on potential reasons for the partial distribution of this immune strategy in bacteria. In this study, we examined how mutations in the bacterial mismatch repair system, which are frequently observed in natural and clinical isolates and cause elevated host mutation rates, influence the evolution of CRISPR-Cas-mediated immunity. We found that hosts with a high mutation rate very rarely evolved CRISPR-based immunity to phage compared to wild-type hosts. We explored the reason for this effect and found that the higher frequency at which surface mutants pre-exist in the mutator host background causes them to rapidly become the dominant phenotype under phage infection. These findings suggest that natural variation in bacterial mutation rates may, therefore, influence the distribution of CRISPR-Cas adaptive immune systems. This article is part of a discussion meeting issue 'The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems'.
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Affiliation(s)
| | | | | | - Edze R. Westra
- ESI and CEC, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9EZ, UK
| | - Clare Rollie
- ESI and CEC, Biosciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9EZ, UK
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38
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Rees VE, Deveson Lucas DS, López-Causapé C, Huang Y, Kotsimbos T, Bulitta JB, Rees MC, Barugahare A, Peleg AY, Nation RL, Oliver A, Boyce JD, Landersdorfer CB. Characterization of Hypermutator Pseudomonas aeruginosa Isolates from Patients with Cystic Fibrosis in Australia. Antimicrob Agents Chemother 2019; 63:e02538-18. [PMID: 30745381 PMCID: PMC6437500 DOI: 10.1128/aac.02538-18] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 01/27/2019] [Indexed: 12/22/2022] Open
Abstract
Hypermutable Pseudomonas aeruginosa isolates (hypermutators) have been identified in patients with cystic fibrosis (CF) and are associated with reduced lung function. Hypermutators display a greatly increased mutation rate and an enhanced ability to become resistant to antibiotics during treatment. Their prevalence has been established among patients with CF, but it has not been determined for patients with CF in Australia. This study aimed to determine the prevalence of hypermutable P. aeruginosa isolates from adult patients with CF from a health care institution in Australia and to characterize the genetic diversity and antibiotic susceptibility of these isolates. A total of 59 P. aeruginosa clinical isolates from patients with CF were characterized. For all isolates, rifampin (RIF) mutation frequencies and susceptibility to a range of antibiotics were determined. Of the 59 isolates, 13 (22%) were hypermutable. Whole-genome sequences were determined for all hypermutable isolates. Core genome polymorphisms were used to assess genetic relatedness of the isolates, both to each other and to a sample of previously characterized P. aeruginosa strains. Phylogenetic analyses showed that the hypermutators were from divergent lineages and that hypermutator phenotype was mostly the result of mutations in mutL or, less commonly, in mutS Hypermutable isolates also contained a range of mutations that are likely associated with adaptation of P. aeruginosa to the CF lung environment. Multidrug resistance was more prevalent in hypermutable than nonhypermutable isolates (38% versus 22%). This study revealed that hypermutable P. aeruginosa strains are common among isolates from patients with CF in Australia and are implicated in the emergence of antibiotic resistance.
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Affiliation(s)
- Vanessa E Rees
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
| | - Deanna S Deveson Lucas
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia
| | - Carla López-Causapé
- Servicio de Microbiología, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma, Palma de Mallorca, Spain
| | - Yuling Huang
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
| | - Tom Kotsimbos
- Allergy, Immunology and Respiratory Medicine Department, Monash University, Melbourne, Victoria, Australia
| | - Jürgen B Bulitta
- Center for Pharmacometrics and Systems Pharmacology, College of Pharmacy, University of Florida, Florida, USA
| | | | - Adele Barugahare
- Monash Bioinformatics Platform, Monash University, Clayton, Victoria, Australia
| | - Anton Y Peleg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia
- Department of Infectious Diseases, The Alfred Hospital and Central Clinical School, Monash University, Melbourne, Australia
| | - Roger L Nation
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
| | - Antonio Oliver
- Servicio de Microbiología, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria de Palma, Palma de Mallorca, Spain
| | - John D Boyce
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Australia
| | - Cornelia B Landersdorfer
- Centre for Medicine Use and Safety, Faculty of Pharmacy and Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), Parkville, Victoria, Australia
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Heterogeneous Antimicrobial Susceptibility Characteristics in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients. mSphere 2018; 3:mSphere00615-17. [PMID: 29564400 PMCID: PMC5853491 DOI: 10.1128/msphere.00615-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/08/2018] [Indexed: 11/22/2022] Open
Abstract
Patients with cystic fibrosis endure “chronic focal infections” with a variety of microorganisms. One microorganism, Pseudomonas aeruginosa, adapts to the host and develops resistance to a wide range of antimicrobials. Interestingly, as the infection progresses, multiple isogenic strains of P. aeruginosa emerge and coexist within the airways of these patients. Despite a common parental origin, the multiple strains of P. aeruginosa develop vastly different susceptibility patterns to actively used antimicrobial agents—a phenomenon we define as “heterogeneous MICs.” By sequencing pairs of P. aeruginosa isolates displaying heterogeneous MICs, we observed widespread isogenic gene lesions in drug transporters, DNA mismatch repair mechanisms, and many other structural or cellular functions. Coupled with the heterogeneous MICs, these genetic lesions demonstrated a symbiotic response to host selection and suggested evolution of a multicellular syntrophic bacterial lifestyle. Current laboratory standard interpretive criteria do not address the emergence of heterogeneous growth and susceptibilities in vitro with treatment implications. Clinical isolates of Pseudomonas aeruginosa from patients with cystic fibrosis (CF) are known to differ from those associated with non-CF hosts by colony morphology, drug susceptibility patterns, and genomic hypermutability. Pseudomonas aeruginosa isolates from CF patients have long been recognized for their overall reduced rate of antimicrobial susceptibility, but their intraclonal MIC heterogeneity has long been overlooked. Using two distinct cohorts of clinical strains (n = 224 from 56 CF patients, n = 130 from 68 non-CF patients) isolated in 2013, we demonstrated profound Etest MIC heterogeneity in CF P. aeruginosa isolates in comparison to non-CF P. aeruginosa isolates. On the basis of whole-genome sequencing of 19 CF P. aeruginosa isolates from 9 patients with heterogeneous MICs, the core genome phylogenetic tree confirmed the within-patient CF P. aeruginosa clonal lineage along with considerable coding sequence variability. No extrachromosomal DNA elements or previously characterized antibiotic resistance mutations could account for the wide divergence in antimicrobial MICs between P. aeruginosa coisolates, though many heterogeneous mutations in efflux and porin genes and their regulators were present. A unique OprD sequence was conserved among the majority of isolates of CF P. aeruginosa analyzed, suggesting a pseudomonal response to selective pressure that is common to the isolates. Genomic sequence data also suggested that CF pseudomonal hypermutability was not entirely due to mutations in mutL, mutS, and uvr. We conclude that the net effect of hundreds of adaptive mutations, both shared between clonally related isolate pairs and unshared, accounts for their highly heterogeneous MIC variances. We hypothesize that this heterogeneity is indicative of the pseudomonal syntrophic-like lifestyle under conditions of being “locked” inside a host focal airway environment for prolonged periods. IMPORTANCE Patients with cystic fibrosis endure “chronic focal infections” with a variety of microorganisms. One microorganism, Pseudomonas aeruginosa, adapts to the host and develops resistance to a wide range of antimicrobials. Interestingly, as the infection progresses, multiple isogenic strains of P. aeruginosa emerge and coexist within the airways of these patients. Despite a common parental origin, the multiple strains of P. aeruginosa develop vastly different susceptibility patterns to actively used antimicrobial agents—a phenomenon we define as “heterogeneous MICs.” By sequencing pairs of P. aeruginosa isolates displaying heterogeneous MICs, we observed widespread isogenic gene lesions in drug transporters, DNA mismatch repair machinery, and many other structural or cellular functions. Coupled with the heterogeneous MICs, these genetic lesions demonstrated a symbiotic response to host selection and suggested evolution of a multicellular syntrophic bacterial lifestyle. Current laboratory standard interpretive criteria do not address the emergence of heterogeneous growth and susceptibilities in vitro with treatment implications.
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Application of directed evolution to develop ethanol tolerant Oenococcus oeni for more efficient malolactic fermentation. Appl Microbiol Biotechnol 2017; 102:921-932. [PMID: 29150706 DOI: 10.1007/s00253-017-8593-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 10/09/2017] [Accepted: 10/12/2017] [Indexed: 10/18/2022]
Abstract
Malolactic fermentation (MLF) is an important step in winemaking, which can be notoriously unreliable due to the fastidious nature of Oenococcus oeni. This study aimed to use directed evolution (DE) to produce a more robust strain of O. oeni having the ability to withstand high ethanol concentrations. DE involves an organism mutating and potentially adapting to a high stress environment over the course of extended cultivation. A continuous culture of O. oeni was established and exposed to progressively increasing ethanol content such that after approximately 330 generations, an isolate from this culture was able to complete MLF in high ethanol content medium earlier than its parent. The ethanol tolerance of a single isolate, A90, was tested to confirm the phenotype and its fermentation performance in wine. In order to investigate the genotypic differences in the evolved strain that led to the ethanol tolerance phenotype, the relative expression of a number of known stress response genes was compared between SB3 and A90. Notably, there was increase in hsp18 expression in 20% (v/v) ethanol by both strains with A90 exhibiting a higher degree of expression. This study is the first to use directed evolution for O. oeni strain improvement and confirms that this technique can be used successfully for the development of new candidate strains for the wine industry. This study also adds to the current knowledge on the genetic basis of ethanol tolerance in this bacterium.
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Barbosa C, Trebosc V, Kemmer C, Rosenstiel P, Beardmore R, Schulenburg H, Jansen G. Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects. Mol Biol Evol 2017; 34:2229-2244. [PMID: 28541480 PMCID: PMC5850482 DOI: 10.1093/molbev/msx158] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
When bacteria evolve resistance against a particular antibiotic, they may simultaneously gain increased sensitivity against a second one. Such collateral sensitivity may be exploited to develop novel, sustainable antibiotic treatment strategies aimed at containing the current, dramatic spread of drug resistance. To date, the presence and molecular basis of collateral sensitivity has only been studied in few bacterial species and is unknown for opportunistic human pathogens such as Pseudomonas aeruginosa. In the present study, we assessed patterns of collateral effects by experimentally evolving 160 independent populations of P. aeruginosa to high levels of resistance against eight commonly used antibiotics. The bacteria evolved resistance rapidly and expressed both collateral sensitivity and cross-resistance. The pattern of such collateral effects differed to those previously reported for other bacterial species, suggesting interspecific differences in the underlying evolutionary trade-offs. Intriguingly, we also identified contrasting patterns of collateral sensitivity and cross-resistance among the replicate populations adapted to the same drug. Whole-genome sequencing of 81 independently evolved populations revealed distinct evolutionary paths of resistance to the selective drug, which determined whether bacteria became cross-resistant or collaterally sensitive towards others. Based on genomic and functional genetic analysis, we demonstrate that collateral sensitivity can result from resistance mutations in regulatory genes such as nalC or mexZ, which mediate aminoglycoside sensitivity in β-lactam-adapted populations, or the two-component regulatory system gene pmrB, which enhances penicillin sensitivity in gentamicin-resistant populations. Our findings highlight substantial variation in the evolved collateral effects among replicates, which in turn determine their potential in antibiotic therapy.
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Affiliation(s)
- Camilo Barbosa
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
| | | | | | - Philip Rosenstiel
- Institute of Clinical Molecular Biology (IKMB), CAU Kiel, Kiel, Germany
| | | | - Hinrich Schulenburg
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
| | - Gunther Jansen
- Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel, Kiel, Germany
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Deihim B, Hassanzadeh M, Shafiei-Jandaghi NZ, Amanlou M, Douraghi M. Characterization of the DNA mismatch repair proteins MutS and MutL in a hypermutator Acinetobacter baumannii. Microb Pathog 2017; 113:74-84. [PMID: 28988868 DOI: 10.1016/j.micpath.2017.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 10/04/2017] [Indexed: 10/18/2022]
Abstract
Mutations of mutS and mutL genes have been linked with the emergence of hypermutator (HPM) phenotype in several bacteria. Nevertheless, there is scarce evidence that these mutations occurred in HPM Acinetobacter baumannii, therefore, it remains unknown whether the mutations located in domains mediating the functions of MutS and MutL. To address this information gap, the nucleotide sequences of mutS and mutL were characterized and their mutations were identified. Additionally, we proposed in silico models of mutated proteins and analyzed the secondary and tertiary structures, and the interaction interfaces of MutL and MutS. The HPM A. baumannii and a wild-type strain were subjected to PCR amplification of full length mutS and mutL, cloning, and sequencing. Following several reads of both strands of each gene and sequence assembly, the mutations were identified. Thereafter, the three-dimensional (3-D) structure of A. baumannii ATCC 19606 was developed and utilized as a template for homology modeling of the mutated amino acid sequences using the Phyre2 and I-TASSER, VMD 1.9.3, LigPlus v.1.4.5, PyMOL v.0.99 software. Regardless of silent mutations (n = 43), 11 missense mutations were identified in the MutS domains of HPM strain such as A4T, T272S, D278N in N-terminus, connector, and core domains, respectively. Three mutations -I357T, A408S, N447S- and 16 silent mutations were observed in MutL. Secondary structure prediction of MutS revealed that the amount of alpha helices, beta sheets, and coils in HPM were 35, 29, and 63, respectively, while these values were 36, 28, and 63 for A. baumannii ATCC 19606 as non mutator. In the case of MutL, for both HPM and non-mutator, 20, 21, and 39 of complete protein were alpha helices, beta sheets, and coils, respectively. Superimposition of structures of MutS of HPM on non-mutator revealed that T272, D278, G457, S528, A533, Y715, and E747 are closely matched with S272, D278, A457, P528, V533, C715, and K747, respectively in non-mutator strain. When the structure of MutL model in HPM was superimposed on its counterpart in non-mutator, all but residues S447, S408, and T357 were identical. Many mutations along the mutS and mutL were noted, but most of the mutations were observed in the interaction interfaces of MutS and MutL. Other substitutions were predominantly detected in C-terminus of MutS that may lead to reduced ATP binding and hydrolysis. Three substitution mutations were adjacent to C-terminus of MutL and are raising the suggestion of reduction in MutL dimerization. It seems that a combination of these mutations is implicated in increased mutation frequency and accordingly emergence of HPM strain.
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Affiliation(s)
- Behnaz Deihim
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Malihe Hassanzadeh
- Department of Medicinal Chemistry and Drug Design and Development Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Massoud Amanlou
- Department of Medicinal Chemistry and Drug Design and Development Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Masoumeh Douraghi
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran; Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran.
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Transient MutS-Based Hypermutation System for Adaptive Evolution of Lactobacillus casei to Low pH. Appl Environ Microbiol 2017; 83:AEM.01120-17. [PMID: 28802267 DOI: 10.1128/aem.01120-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/01/2017] [Indexed: 11/20/2022] Open
Abstract
This study explored transient inactivation of the gene encoding the DNA mismatch repair enzyme MutS as a tool for adaptive evolution of Lactobacillus casei MutS deletion derivatives of L. casei 12A and ATCC 334 were constructed and subjected to a 100-day adaptive evolution process to increase lactic acid resistance at low pH. Wild-type parental strains were also subjected to this treatment. At the end of the process, the ΔmutS lesion was repaired in representative L. casei 12A and ATCC 334 ΔmutS mutant isolates. Growth studies in broth at pH 4.0 (titrated with lactic acid) showed that all four adapted strains grew more rapidly, to higher cell densities, and produced significantly more lactic acid than untreated wild-type cells. However, the adapted ΔmutS derivative mutants showed the greatest increases in growth and lactic acid production. Further characterization of the L. casei 12A-adapted ΔmutS derivative revealed that it had a significantly smaller cell volume, a rougher cell surface, and significantly better survival at pH 2.5 than parental L. casei 12A. Genome sequence analysis confirmed that transient mutS inactivation decreased DNA replication fidelity in both L. casei strains, and it identified genetic changes that might contribute to the lactic acid-resistant phenotypes of adapted cells. Targeted inactivation of three genes that had acquired nonsense mutations in the adapted L. casei 12A ΔmutS mutant derivative showed that NADH dehydrogenase (ndh), phosphate transport ATP-binding protein PstB (pstB), and two-component signal transduction system (TCS) quorum-sensing histidine protein kinase (hpk) genes act in combination to increase lactic acid resistance in L. casei 12A.IMPORTANCE Adaptive evolution has been applied to microorganisms to increase industrially desirable phenotypes, including acid resistance. We developed a method to increase the adaptability of Lactobacillus casei 12A and ATCC 334 through transient inactivation of the DNA mismatch repair enzyme MutS. Here, we show this method was effective in increasing the resistance of L. casei to lactic acid at low pH. Additionally, we identified three genes that contribute to increased acid resistance in L. casei 12A. These results provide valuable insight on methods to enhance an organism's fitness to complex phenotypes through adaptive evolution and targeted gene inactivation.
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Ilmjärv T, Naanuri E, Kivisaar M. Contribution of increased mutagenesis to the evolution of pollutants-degrading indigenous bacteria. PLoS One 2017; 12:e0182484. [PMID: 28777807 PMCID: PMC5544203 DOI: 10.1371/journal.pone.0182484] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 07/19/2017] [Indexed: 12/20/2022] Open
Abstract
Bacteria can rapidly evolve mechanisms allowing them to use toxic environmental pollutants as a carbon source. In the current study we examined whether the survival and evolution of indigenous bacteria with the capacity to degrade organic pollutants could be connected with increased mutation frequency. The presence of constitutive and transient mutators was monitored among 53 pollutants-degrading indigenous bacterial strains. Only two strains expressed a moderate mutator phenotype and six were hypomutators, which implies that constitutively increased mutability has not been prevalent in the evolution of pollutants degrading bacteria. At the same time, a large proportion of the studied indigenous strains exhibited UV-irradiation-induced mutagenesis, indicating that these strains possess error-prone DNA polymerases which could elevate mutation frequency transiently under the conditions of DNA damage. A closer inspection of two Pseudomonas fluorescens strains PC20 and PC24 revealed that they harbour genes for ImuC (DnaE2) and more than one copy of genes for Pol V. Our results also revealed that availability of other nutrients in addition to aromatic pollutants in the growth environment of bacteria affects mutagenic effects of aromatic compounds. These results also implied that mutagenicity might be affected by a factor of how long bacteria have evolved to use a particular pollutant as a carbon source.
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Affiliation(s)
- Tanel Ilmjärv
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Eve Naanuri
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Maia Kivisaar
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
- * E-mail:
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Bridier A, Piard JC, Pandin C, Labarthe S, Dubois-Brissonnet F, Briandet R. Spatial Organization Plasticity as an Adaptive Driver of Surface Microbial Communities. Front Microbiol 2017; 8:1364. [PMID: 28775718 PMCID: PMC5517491 DOI: 10.3389/fmicb.2017.01364] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 07/05/2017] [Indexed: 01/08/2023] Open
Abstract
Biofilms are dynamic habitats which constantly evolve in response to environmental fluctuations and thereby constitute remarkable survival strategies for microorganisms. The modulation of biofilm functional properties is largely governed by the active remodeling of their three-dimensional structure and involves an arsenal of microbial self-produced components and interconnected mechanisms. The production of matrix components, the spatial reorganization of ecological interactions, the generation of physiological heterogeneity, the regulation of motility, the production of actives enzymes are for instance some of the processes enabling such spatial organization plasticity. In this contribution, we discussed the foundations of architectural plasticity as an adaptive driver of biofilms through the review of the different microbial strategies involved. Moreover, the possibility to harness such characteristics to sculpt biofilm structure as an attractive approach to control their functional properties, whether beneficial or deleterious, is also discussed.
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Affiliation(s)
- Arnaud Bridier
- Antibiotics, Biocides, Residues and Resistance Unit, Fougères Laboratory, ANSESFougères, France
| | - Jean-Christophe Piard
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
| | - Caroline Pandin
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
| | - Simon Labarthe
- MaIAGE, INRA, Université Paris-SaclayJouy-en-Josas, France
| | | | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-SaclayJouy-en-Josas, France
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46
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Pires DP, Dötsch A, Anderson EM, Hao Y, Khursigara CM, Lam JS, Sillankorva S, Azeredo J. A Genotypic Analysis of Five P. aeruginosa Strains after Biofilm Infection by Phages Targeting Different Cell Surface Receptors. Front Microbiol 2017; 8:1229. [PMID: 28713356 PMCID: PMC5492357 DOI: 10.3389/fmicb.2017.01229] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/16/2017] [Indexed: 12/19/2022] Open
Abstract
Antibiotic resistance constitutes one of the most serious threats to the global public health and urgently requires new and effective solutions. Bacteriophages are bacterial viruses increasingly recognized as being good alternatives to traditional antibiotic therapies. In this study, the efficacy of phages, targeting different cell receptors, against Pseudomonas aeruginosa PAO1 biofilm and planktonic cell cultures was evaluated over the course of 48 h. Although significant reductions in the number of viable cells were achieved for both cases, the high level of adaptability of the bacteria in response to the selective pressure caused by phage treatment resulted in the emergence of phage-resistant variants. To further investigate the genetic makeup of phage-resistant variants isolated from biofilm infection experiments, some of these bacteria were selected for phenotypic and genotypic characterization. Whole genome sequencing was performed on five phage-resistant variants and all of them carried mutations affecting the galU gene as well as one of pil genes. The sequencing analysis further revealed that three of the P. aeruginosa PAO1 variants carry large deletions (>200 kbp) in their genomes. Complementation of the galU mutants with wild-type galU in trans restored LPS expression on the bacterial cell surface of these bacterial strains and rendered the complemented strains to be sensitive to phages. This provides unequivocal evidence that inactivation of galU function was associated with resistance to the phages that uses LPS as primary receptors. Overall, this work demonstrates that P. aeruginosa biofilms can survive phage attack and develop phage-resistant variants exhibiting defective LPS production and loss of type IV pili that are well adapted to the biofilm mode of growth.
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Affiliation(s)
- Diana P. Pires
- CEB-Centre of Biological Engineering, Universidade do MinhoBraga, Portugal
| | - Andreas Dötsch
- Institute of Functional Interfaces, Karlsruhe Institute of TechnologyEggenstein-Leopoldshafen, Germany
| | - Erin M. Anderson
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, GuelphON, Canada
| | - Youai Hao
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, GuelphON, Canada
| | - Cezar M. Khursigara
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, GuelphON, Canada
| | - Joseph S. Lam
- Department of Molecular and Cellular Biology, College of Biological Science, University of Guelph, GuelphON, Canada
| | - Sanna Sillankorva
- CEB-Centre of Biological Engineering, Universidade do MinhoBraga, Portugal
| | - Joana Azeredo
- CEB-Centre of Biological Engineering, Universidade do MinhoBraga, Portugal
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47
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Lynch M, Ackerman MS, Gout JF, Long H, Sung W, Thomas WK, Foster PL. Genetic drift, selection and the evolution of the mutation rate. Nat Rev Genet 2017; 17:704-714. [PMID: 27739533 DOI: 10.1038/nrg.2016.104] [Citation(s) in RCA: 438] [Impact Index Per Article: 62.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
As one of the few cellular traits that can be quantified across the tree of life, DNA-replication fidelity provides an excellent platform for understanding fundamental evolutionary processes. Furthermore, because mutation is the ultimate source of all genetic variation, clarifying why mutation rates vary is crucial for understanding all areas of biology. A potentially revealing hypothesis for mutation-rate evolution is that natural selection primarily operates to improve replication fidelity, with the ultimate limits to what can be achieved set by the power of random genetic drift. This drift-barrier hypothesis is consistent with comparative measures of mutation rates, provides a simple explanation for the existence of error-prone polymerases and yields a formal counter-argument to the view that selection fine-tunes gene-specific mutation rates.
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Affiliation(s)
- Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Matthew S Ackerman
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Jean-Francois Gout
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Hongan Long
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - Way Sung
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
| | - W Kelley Thomas
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Patricia L Foster
- Department of Biology, Indiana University, Bloomington, Indiana 47401, USA
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48
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Kint N, Janoir C, Monot M, Hoys S, Soutourina O, Dupuy B, Martin-Verstraete I. The alternative sigma factor σ B plays a crucial role in adaptive strategies of Clostridium difficile during gut infection. Environ Microbiol 2017; 19:1933-1958. [PMID: 28198085 DOI: 10.1111/1462-2920.13696] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/19/2017] [Accepted: 01/22/2017] [Indexed: 12/29/2022]
Abstract
Clostridium difficile is a major cause of diarrhoea associated with antibiotherapy. Exposed to stresses in the gut, C. difficile can survive by inducing protection, detoxification and repair systems. In several firmicutes, most of these systems are controlled by the general stress response involving σB . In this work, we studied the role of σB in the physiopathology of C. difficile. We showed that the survival of the sigB mutant during the stationary phase was reduced. Using a transcriptome analysis, we showed that σB controls the expression of ∼25% of genes including genes involved in sporulation, metabolism, cell surface biogenesis and the management of stresses. By contrast, σB does not control toxin gene expression. In agreement with the up-regulation of sporulation genes, the sporulation efficiency is higher in the sigB mutant than in the wild-type strain. sigB inactivation also led to increased sensitivity to acidification, cationic antimicrobial peptides, nitric oxide and ROS. In addition, we showed for the first time that σB also plays a crucial role in oxygen tolerance in this strict anaerobe. Finally, we demonstrated that the fitness of colonisation by the sigB mutant is greatly affected in a dixenic mouse model of colonisation when compared to the wild-type strain.
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Affiliation(s)
- Nicolas Kint
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Claire Janoir
- EA 4043, Unité Bactéries Pathogènes et Santé (UBaPS), Université Paris-Sud, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Marc Monot
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Sandra Hoys
- EA 4043, Unité Bactéries Pathogènes et Santé (UBaPS), Université Paris-Sud, Université Paris-Saclay, 92290, Châtenay-Malabry, France
| | - Olga Soutourina
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Bruno Dupuy
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Isabelle Martin-Verstraete
- Laboratoire Pathogénese des Bactéries Anaérobies, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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49
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Hua X, Bromham L. Darwinism for the Genomic Age: Connecting Mutation to Diversification. Front Genet 2017; 8:12. [PMID: 28224003 PMCID: PMC5293951 DOI: 10.3389/fgene.2017.00012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 01/19/2017] [Indexed: 12/30/2022] Open
Abstract
A growing body of evidence suggests that rates of diversification of biological lineages are correlated with differences in genome-wide mutation rate. Given that most research into differential patterns of diversification rate have focused on species traits or ecological parameters, a connection to the biochemical processes of genome change is an unexpected observation. While the empirical evidence for a significant association between mutation rate and diversification rate is mounting, there has been less effort in explaining the factors that mediate this connection between genetic change and species richness. Here we draw together empirical studies and theoretical concepts that may help to build links in the explanatory chain that connects mutation to diversification. First we consider the way that mutation rates vary between species. We then explore how differences in mutation rates have flow-through effects to the rate at which populations acquire substitutions, which in turn influences the speed at which populations become reproductively isolated from each other due to the acquisition of genomic incompatibilities. Since diversification rate is commonly measured from phylogenetic analyses, we propose a conceptual approach for relating events of reproductive isolation to bifurcations on molecular phylogenies. As we examine each of these relationships, we consider theoretical models that might shine a light on the observed association between rate of molecular evolution and diversification rate, and critically evaluate the empirical evidence for these links, focusing on phylogenetic comparative studies. Finally, we ask whether we are getting closer to a real understanding of the way that the processes of molecular evolution connect to the observable patterns of diversification.
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Affiliation(s)
- Xia Hua
- Centre for Macroevolution and Macroecology, Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Lindell Bromham
- Centre for Macroevolution and Macroecology, Research School of Biology, Australian National University, Canberra ACT, Australia
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50
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Abstract
Bacteria face a trade-off between genetic fidelity, which reduces deleterious mistakes in the genome, and genetic innovation, which allows organisms to adapt. Evidence suggests that many bacteria balance this trade-off by modulating their mutation rates, but few mechanisms have been described for such modulation. Following experimental evolution and whole-genome resequencing of the marine bacterium Vibrio splendidus 12B01, we discovered one such mechanism, which allows this bacterium to switch to an elevated mutation rate. This switch is driven by the excision of a mobile element residing in mutS, which encodes a DNA mismatch repair protein. When integrated within the bacterial genome, the mobile element provides independent promoter and translation start sequences for mutS—different from the bacterium’s original mutS promoter region—which allow the bacterium to make a functional mutS gene product. Excision of this mobile element rejoins the mutS gene with host promoter and translation start sequences but leaves a 2-bp deletion in the mutS sequence, resulting in a frameshift and a hypermutator phenotype. We further identified hundreds of clinical and environmental bacteria across Betaproteobacteria and Gammaproteobacteria that possess putative mobile elements within the same amino acid motif in mutS. In a subset of these bacteria, we detected excision of the element but not a frameshift mutation; the mobile elements leave an intact mutS coding sequence after excision. Our findings reveal a novel mechanism by which one bacterium alters its mutation rate and hint at a possible evolutionary role for mobile elements within mutS in other bacteria. DNA mutations are a double-edged sword. Most mutations are harmful; they can scramble precise genetic sequences honed over thousands of generations. But in rare cases, mutations also produce beneficial new traits that allow populations to adapt to changing environments. Recent evidence suggests that some bacteria balance this trade-off by altering their mutation rates to suit their environment. To date, however, we know of few mechanisms that allow bacteria to change their mutation rates. We describe one such mechanism, driven by the action of a mobile element, in the marine bacterium Vibrio splendidus 12B01. We also found similar mobile genetic sequences in the mutS genes of many different bacteria, including clinical and agricultural pathogens. These mobile elements might play an as yet unknown role in the evolution of these important bacteria.
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