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Loghmani SB, Zitzow E, Schwarzmüller L, Humboldt Y, Eisenberg P, Kreikemeyer B, Veith N, Kummer U, Fiedler T. Comparing genome-scale metabolic models of the non-resistant Enterococcus faecalis ATCC 19433 and the multi-resistant Enterococcus faecalis V583. J Biotechnol 2024; 392:109-117. [PMID: 38996920 DOI: 10.1016/j.jbiotec.2024.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 06/26/2024] [Accepted: 07/08/2024] [Indexed: 07/14/2024]
Abstract
Enterococcus faecalis is a versatile lactic acid bacterium with a large variety of implications for humans. While some strains of this species are pathobionts being resistant against most of the common antibiotics, other strains are regarded as biological protectants or even probiotics. Accordingly, E. faecalis strains largely differ in the size and content of their accessory genome. In this study, we describe the genome-scale metabolic network reconstruction of E. faecalis ATCC 19433, a non-resistant human-associated strain. A comparison of the genome-scale metabolic model (GSM) of E. faecalis ATCC 19433 with a previously published GSM of the multi-resistant pathobiontic E. faecalis V583 reveals high similarities in the central metabolic abilities of these two human associated strains. This is reflected, e.g., in the identical amino acid auxotrophies. The ATCC 19433 strain, however, has a 14.1 % smaller genome than V583 and lacks the multiple antibiotic resistance genes and genes involved in capsule formation. Based on the measured metabolic fluxes at different growth rates, the energy demand at zero growth was calculated to be about 40 % lower for the ATCC 19433 strain compared to V583. Furthermore, the ATCC 19433 strain seems less prone to the depletion of amino acids utilizable for energy metabolism. This might hint at a lower overall energy demand of the ATCC 19433 strain as compared to V583.
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Affiliation(s)
- Seyed Babak Loghmani
- Ruprecht-Karls University Heidelberg, Bioquant, Center for Organismal Studies, Im Neuenheimer Feld 276, Heidelberg 69120, Germany
| | - Eric Zitzow
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology and Hygiene, Schillingallee 70, Rostock 18057, Germany
| | - Luisa Schwarzmüller
- Ruprecht-Karls University Heidelberg, Bioquant, Center for Organismal Studies, Im Neuenheimer Feld 276, Heidelberg 69120, Germany
| | - Yvonne Humboldt
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology and Hygiene, Schillingallee 70, Rostock 18057, Germany
| | - Philip Eisenberg
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology and Hygiene, Schillingallee 70, Rostock 18057, Germany
| | - Bernd Kreikemeyer
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology and Hygiene, Schillingallee 70, Rostock 18057, Germany
| | - Nadine Veith
- Ruprecht-Karls University Heidelberg, Bioquant, Center for Organismal Studies, Im Neuenheimer Feld 276, Heidelberg 69120, Germany
| | - Ursula Kummer
- Ruprecht-Karls University Heidelberg, Bioquant, Center for Organismal Studies, Im Neuenheimer Feld 276, Heidelberg 69120, Germany
| | - Tomas Fiedler
- Rostock University Medical Centre, Institute of Medical Microbiology, Virology and Hygiene, Schillingallee 70, Rostock 18057, Germany.
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2
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Alrafaie AM, Pyrzanowska K, Smith EM, Partridge DG, Rafferty J, Mesnage S, Shepherd J, Stafford GP. A diverse set of Enterococcus-infecting phage provides insight into phage host-range determinants. Virus Res 2024; 347:199426. [PMID: 38960003 PMCID: PMC11269942 DOI: 10.1016/j.virusres.2024.199426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 06/18/2024] [Accepted: 06/21/2024] [Indexed: 07/05/2024]
Abstract
Enterococci are robust Gram-positive bacteria that pose a significant threat in healthcare settings due to antibiotic resistance, with vancomycin-resistant enterococci (VRE) most prominent. To tackle this issue, bacteriophages (bacterial viruses) can be exploited as they specifically and efficiently target bacteria. Here, we successfully isolated and characterised a set of novel phages: SHEF10, SHEF11, SHEF13, SHEF14, and SHEF16 which target E. faecalis (SHEF10,11,13), or E. faecium (SHEF13, SHEF14 & SHEF16) strains including a range of clinical and VRE isolates. Genomic analysis shows that all phages are strictly lytic and diverse in terms of genome size and content, quickly and effectively lysing strains at different multiplicity of infections. Detailed analysis of the broad host-range SHEF13 phage revealed the crucial role of the enterococcal polysaccharide antigen (EPA) variable region in its infection of E. faecalis V583. In parallel, the discovery of a carbohydrate-targeting domain (CBM22) found conserved within the three phage genomes indicates a role in cell surface interactions that may be important in phage-bacterial interactons. These findings advance our comprehension of phage-host interactions and pave the way for targeted therapeutic strategies against antibiotic-resistant enterococcal infections.
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Affiliation(s)
- Alhassan M Alrafaie
- Department of Medical Laboratory, College of Applied Medical Sciences in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia.
| | - Karolina Pyrzanowska
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom, S10 2TA, UK
| | - Elspeth M Smith
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom, S10 2TA, UK
| | - David G Partridge
- Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield S10 2JF, UK
| | - John Rafferty
- School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Stephane Mesnage
- School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | - Joanna Shepherd
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom, S10 2TA, UK
| | - Graham P Stafford
- School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom, S10 2TA, UK; School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
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3
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Olanrewaju OS, Molale-Tom LG, Bezuidenhout CC. Genomic diversity, antibiotic resistance, and virulence in South African Enterococcus faecalis and Enterococcus lactis isolates. World J Microbiol Biotechnol 2024; 40:289. [PMID: 39102038 DOI: 10.1007/s11274-024-04098-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 07/27/2024] [Indexed: 08/06/2024]
Abstract
This study presents the empirical findings of an in-depth genomic analysis of Enterococcus faecalis and Enterococcus lactis isolates from South Africa. It offers valuable insights into their genetic characteristics and their significant implications for public health. The study uncovers nuanced variations in the gene content of these isolates, despite their similar GC contents, providing a comprehensive view of the evolutionary diversity within the species. Genomic islands are identified, particularly in E. faecalis, emphasizing its propensity for horizontal gene transfer and genetic diversity, especially in terms of antibiotic resistance genes. Pangenome analysis reveals the existence of a core genome, accounting for a modest proportion of the total genes, with 2157 core genes, 1164 shell genes, and 4638 cloud genes out of 7959 genes in 52 South African E. faecalis genomes (2 from this study, 49 south Africa genomes downloaded from NCBI, and E. faecalis reference genome). Detecting large-scale genomic rearrangements, including chromosomal inversions, underscores the dynamic nature of bacterial genomes and their role in generating genetic diversity. The study uncovers an array of antibiotic resistance genes, with trimethoprim, tetracycline, glycopeptide, and multidrug resistance genes prevalent, raising concerns about the effectiveness of antibiotic treatment. Virulence gene profiling unveils a diverse repertoire of factors contributing to pathogenicity, encompassing adhesion, biofilm formation, stress resistance, and tissue damage. These empirical findings provide indispensable insights into these bacteria's genomic dynamics, antibiotic resistance mechanisms, and virulence potential, underlining the pressing need to address antibiotic resistance and implement robust control measures.
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Affiliation(s)
- Oluwaseyi Samuel Olanrewaju
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa.
| | - Lesego G Molale-Tom
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa.
| | - Cornelius C Bezuidenhout
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom Campus, Private Bag X6001, Potchefstroom, 2520, South Africa
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Snell A, Manias DA, Elbehery RR, Dunny GM, Willett JLE. Arginine impacts aggregation, biofilm formation, and antibiotic susceptibility in Enterococcus faecalis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596650. [PMID: 38853917 PMCID: PMC11160706 DOI: 10.1101/2024.05.30.596650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Enterococcus faecalis is a commensal bacterium in the gastrointestinal tract (GIT) of humans and other organisms. E. faecalis also causes infections in root canals, wounds, the urinary tract, and on heart valves. E. faecalis metabolizes arginine through the arginine deiminase (ADI) pathway, which converts arginine to ornithine and releases ATP, ammonia, and CO2. E. faecalis arginine metabolism also affects virulence of other pathogens during co-culture. E. faecalis may encounter elevated levels of arginine in the GIT or the oral cavity, where arginine is used as a dental therapeutic. Little is known about how E. faecalis responds to growth in arginine in the absence of other bacteria. To address this, we used RNAseq and additional assays to measure growth, gene expression, and biofilm formation in E. faecalis OG1RF grown in arginine. We demonstrate that arginine decreases E. faecalis biofilm production and causes widespread differential expression of genes related to metabolism, quorum sensing, and polysaccharide synthesis. Growth in arginine also increases aggregation of E. faecalis and promotes decreased susceptibility to the antibiotics ampicillin and ceftriaxone. This work provides a platform for understanding of how the presence of arginine in biological niches affects E. faecalis physiology and virulence of surrounding microbes.
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Affiliation(s)
- Alex Snell
- University of Minnesota Medical School, Minneapolis, MN, 55455
| | - Dawn A. Manias
- University of Minnesota Medical School, Minneapolis, MN, 55455
| | | | - Gary M. Dunny
- University of Minnesota Medical School, Minneapolis, MN, 55455
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Sangiorgio G, Calvo M, Migliorisi G, Campanile F, Stefani S. The Impact of Enterococcus spp. in the Immunocompromised Host: A Comprehensive Review. Pathogens 2024; 13:409. [PMID: 38787261 PMCID: PMC11124283 DOI: 10.3390/pathogens13050409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 05/05/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
The immunocompromised host is usually vulnerable to infectious diseases due to broad-spectrum treatments and immunological dysregulation. The Enterococcus genus consists of normal gut commensals, which acquire a leading role in infective processes among individuals with compromised immune systems. These microorganisms may express a potential virulence and resistance spectrum, enabling their function as severe pathogens. The Enterococcus spp. infections in immunocompromised hosts appear to be difficult to resolve due to the immunological response impairment and the possibility of facing antimicrobial-resistant strains. As regards the related risk factors, several data demonstrated that prior antibiotic exposure, medical device insertion, prolonged hospitalization and surgical interventions may lead to Enterococcus overgrowth, antibiotic resistance and spread among critical healthcare settings. Herein, we present a comprehensive review of Enterococcus spp. in the immunocompromised host, summarizing the available knowledge about virulence factors, antimicrobial-resistance mechanisms and host-pathogen interaction. The review ultimately yearns for more substantial support to further investigations about enterococcal infections and immunocompromised host response.
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Affiliation(s)
- Giuseppe Sangiorgio
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via Santa Sofia 97, 95123 Catania, Italy; (F.C.); (S.S.)
| | - Maddalena Calvo
- U.O.C. Laboratory Analysis Unit, University Hospital Policlinico-San Marco, Via Santa Sofia 78, 95123 Catania, Italy; (M.C.); (G.M.)
| | - Giuseppe Migliorisi
- U.O.C. Laboratory Analysis Unit, University Hospital Policlinico-San Marco, Via Santa Sofia 78, 95123 Catania, Italy; (M.C.); (G.M.)
| | - Floriana Campanile
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via Santa Sofia 97, 95123 Catania, Italy; (F.C.); (S.S.)
| | - Stefania Stefani
- Department of Biomedical and Biotechnological Sciences, University of Catania, Via Santa Sofia 97, 95123 Catania, Italy; (F.C.); (S.S.)
- U.O.C. Laboratory Analysis Unit, University Hospital Policlinico-San Marco, Via Santa Sofia 78, 95123 Catania, Italy; (M.C.); (G.M.)
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Salamzade R, Tran P, Martin C, Manson AL, Gilmore MS, Earl AM, Anantharaman K, Kalan LR. zol & fai: large-scale targeted detection and evolutionary investigation of gene clusters. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.07.544063. [PMID: 37333121 PMCID: PMC10274777 DOI: 10.1101/2023.06.07.544063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Many universally and conditionally important genes are genomically aggregated within clusters. Here, we introduce fai and zol, which together enable large-scale comparative analysis of different types of gene clusters and mobile-genetic elements (MGEs), such as biosynthetic gene clusters (BGCs) or viruses. Fundamentally, they overcome a current bottleneck to reliably perform comprehensive orthology inference at large scale across broad taxonomic contexts and thousands of genomes. First, fai allows the identification of orthologous or homologous instances of a query gene cluster of interest amongst a database of target genomes. Subsequently, zol enables reliable, context-specific inference of protein-encoding ortholog groups for individual genes across gene cluster instances. In addition, zol performs functional annotation and computes a variety of statistics for each inferred ortholog group. These programs are showcased through application to: (i) longitudinal tracking of a virus in metagenomes, (ii) discovering novel population-genetic insights of two common BGCs in a fungal species, and (iii) uncovering large-scale evolutionary trends of a virulence-associated gene cluster across thousands of genomes from a diverse bacterial genus.
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Affiliation(s)
- Rauf Salamzade
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Patricia Tran
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
- Freshwater and Marine Science Doctoral Program, University of Wisconsin-Madison, WI, USA
| | - Cody Martin
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA
| | - Abigail L. Manson
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Michael S. Gilmore
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
- Department of Ophthalmology, Harvard Medical School and Mass Eye and Ear, Boston, Massachusetts, USA
- Department of Microbiology, Harvard Medical School and Mass Eye and Ear, Boston, Massachusetts, USA
| | - Ashlee M. Earl
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | | | - Lindsay R. Kalan
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Department of Medicine, Division of Infectious Disease, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- M.G. DeGroote Institute for Infectious Disease Research, David Braley Centre for Antibiotic Discovery, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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7
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Alrafaie AM, Stafford GP. Enterococcal bacteriophage: A survey of the tail associated lysin landscape. Virus Res 2023; 327:199073. [PMID: 36787848 DOI: 10.1016/j.virusres.2023.199073] [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: 10/12/2022] [Revised: 02/05/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023]
Abstract
Bacteriophages are viruses that exclusively infect bacteria which require local degradation of cell barriers. This degradation is accomplished by various lysins located mainly within the phage tail structure. In this paper we surveyed and analysed the genomes of 506 isolated bacteriophage and prophage infecting or harboured within the genomes of the medically important Enterococcus faecalis and faecium. We highlight and characterise the major features of the genomes of phage in the morphological groups podovirus, siphovirus and myovirus, and explore their categorisation according to the new ICTV classifications, with a focus on putative extracellular lysins chiefly within tail modules. Our analysis reveals a range of potential cell-wall targeting enzyme domains that are part of tail, tape measure or other predicted base structures of these phages or prophages. These largely fall into protein domains targeting pentapeptide or glycosidic linkages within peptidoglycan but also potentially the enterococcal polysaccharide antigen (EPA) and wall teichoic acids of these species (i.e., Pectinesterases and Phosphodiesterases). Notably, there is a great variety of domain architectures that reveal the diversity of evolutionary solutions to attack the Enterococcus cell wall. Despite this variety, most phage and prophage possess a putative endopeptidase (70%), reflecting the ubiquity of this cell surface barrier. We also identified a predicted lytic transglycosylase domain belonging to the glycosyl hydrolase (GH) family 23 and present exclusively within tape measure proteins. Our data also reveal distinct features of the genomes of podo-, sipho- and myo-type viruses that most likely relate to their size and complexity. Overall, we lay a foundation for expression of recombinant TAL proteins and engineering of enterococcal and other phage that will be invaluable for researchers in this field.
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Affiliation(s)
- Alhassan M Alrafaie
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom; Department of Medical Laboratory Sciences, College of Applied Medical Sciences in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia.
| | - Graham P Stafford
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, United Kingdom.
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van der Put RM, Metz B, Pieters RJ. Carriers and Antigens: New Developments in Glycoconjugate Vaccines. Vaccines (Basel) 2023; 11:vaccines11020219. [PMID: 36851097 PMCID: PMC9962112 DOI: 10.3390/vaccines11020219] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/05/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Glycoconjugate vaccines have proven their worth in the protection and prevention of infectious diseases. The introduction of the Haemophilus influenzae type b vaccine is the prime example, followed by other glycoconjugate vaccines. Glycoconjugate vaccines consist of two components: the carrier protein and the carbohydrate antigen. Current carrier proteins are tetanus toxoid, diphtheria toxoid, CRM197, Haemophilus protein D and the outer membrane protein complex of serogroup B meningococcus. Carbohydrate antigens have been produced mainly by extraction and purification from the original host. However, current efforts show great advances in the development of synthetically produced oligosaccharides and bioconjugation. This review evaluates the advances of glycoconjugate vaccines in the last five years. We focus on developments regarding both new carriers and antigens. Innovative developments regarding carriers are outer membrane vesicles, glycoengineered proteins, new carrier proteins, virus-like particles, protein nanocages and peptides. With regard to conjugated antigens, we describe recent developments in the field of antimicrobial resistance (AMR) and ESKAPE pathogens.
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Affiliation(s)
- Robert M.F. van der Put
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
- Correspondence:
| | - Bernard Metz
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Roland J. Pieters
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
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The Regulations of Essential WalRK Two-Component System on Enterococcus faecalis. J Clin Med 2023; 12:jcm12030767. [PMID: 36769415 PMCID: PMC9917794 DOI: 10.3390/jcm12030767] [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: 11/09/2022] [Revised: 01/04/2023] [Accepted: 01/10/2023] [Indexed: 01/20/2023] Open
Abstract
Enterococcus faecalis (E. faecalis) is a Gram-positive, facultative anaerobic bacterium that is highly adaptable to its environment. In humans, it can cause serious infections with biofilm formation. With increasing attention on its health threat, prevention and control of biofilm formation in E. faecalis have been observed. Many factors including polysaccharides as well as autolysis, proteases, and eDNA regulate biofilm formation. Those contributors are regulated by several important regulatory systems involving the two-component signal transduction system (TCS) for its adaptation to the environment. Highly conserved WalRK as one of 17 TCSs is the only essential TCS in E. faecalis. In addition to biofilm formation, various metabolisms, including cell wall construction, drug resistance, as well as interactions among regulatory systems and resistance to the host immune system, can be modulated by the WalRK system. Therefore, WalRK has been identified as a key target for E. faecalis infection control. In the present review, the regulation of WalRK on E. faecalis pathogenesis and associated therapeutic strategies are demonstrated.
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Huang Y, Eeckhaut V, Goossens E, Rasschaert G, Van Erum J, Roovers G, Ducatelle R, Antonissen G, Van Immerseel F. Bacterial chondronecrosis with osteomyelitis related Enterococcus cecorum isolates are genetically distinct from the commensal population and are more virulent in an embryo mortality model. Vet Res 2023; 54:13. [PMID: 36823606 PMCID: PMC9951403 DOI: 10.1186/s13567-023-01146-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 02/01/2023] [Indexed: 02/25/2023] Open
Abstract
Bacterial chondronecrosis with osteomyelitis (BCO) is a common cause of broiler lameness. Bacteria that are found in BCO lesions are intestinal bacteria that are proposed to have translocated through the intestinal epithelium and have spread systemically. One of the specific bacterial species frequently isolated in BCO cases is Enterococcus cecorum. In the current study, caecal isolates were obtained from birds derived from healthy flocks (12 isolates from 6 flocks), while isolates derived from caeca, colon, pericardium, caudal thoracic vertebrae, coxo-femoral joint, knee joint and intertarsal joint (hock) were obtained from broilers derived from BCO outbreaks (111 isolates from 10 flocks). Pulsed field gel electrophoresis was performed to determine similarity. Clonal E. cecorum populations were isolated from different bones/joints and pericardium from animals within the same flock, with intestinal strains carrying the same pulsotype, pointing to the intestinal origin of the systemically present bacteria. Isolates from the intestinal tract of birds from healthy flocks clustered away from the BCO strains. Isolates from the gut, bones/joints and pericardium of affected animals contained a set of genes that were absent in isolates from the gut of healthy animals, such as genes encoding for enterococcal polysaccharide antigens (epa genes), cell wall structural components and nutrient transporters. Isolates derived from the affected birds induced a significant higher mortality in the embryo mortality model as compared to the isolates from the gut of healthy birds, pointing to an increased virulence.
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Affiliation(s)
- Yue Huang
- grid.5342.00000 0001 2069 7798Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Venessa Eeckhaut
- grid.5342.00000 0001 2069 7798Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Evy Goossens
- grid.5342.00000 0001 2069 7798Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Geertrui Rasschaert
- Flanders Research Institute for Agriculture, Fisheries and Food (ILVO)- Technology and Food Science Unit, 9090 Melle, Belgium
| | | | | | - Richard Ducatelle
- grid.5342.00000 0001 2069 7798Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Gunther Antonissen
- grid.5342.00000 0001 2069 7798Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Filip Van Immerseel
- Livestock Gut Health Team (LiGHT), Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
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11
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Bipartite rgp Locus Diversity in Streptococcus thermophilus Corresponds to Backbone and Side Chain Differences of Its Rhamnose-Containing Cell Wall Polysaccharide. Appl Environ Microbiol 2022; 88:e0150422. [PMID: 36350137 PMCID: PMC9746298 DOI: 10.1128/aem.01504-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The rhamnose-glucose polysaccharide (Rgp) of Streptococcus thermophilus represents a major cell wall component, and the gene cluster responsible for its biosynthesis (termed rgp) has recently been identified. Significant genetic diversity among these loci has previously been reported, with five distinct rgp genotypes identified (designated rgp1 through -5). In the present study, two additional genotypes were identified (designated rgp6 and rgp7) through comparative analysis of the rgp loci of 78 Streptococcus thermophilus genomes. The rgp locus of a given S. thermophilus strain encoded the biosynthetic machinery for a rhamnan-rich backbone and a variable side chain component, the latter being associated with the highly specific interactions with many bacteriophages that infect this species. The chemical structure of the Rgp from three S. thermophilus strains, representing the rgp2, -3, and -4 genotypes, was elucidated, and based on bioinformatic and biochemical analyses we propose a model for Rgp biosynthesis in dairy streptococci. Furthermore, we exploited the genetic diversity within the S. thermophilus bipartite rgp locus to develop a two-step multiplex PCR system to classify strains based on gene content associated with the biosynthesis of the variable side chain structure as well as the rhamnan backbone. IMPORTANCE Streptococcus thermophilus is present and applied in industrial and artisanal dairy fermentations for the production of various cheeses and yogurt. During these fermentations, S. thermophilus is vulnerable to phage predation, and recent studies have identified the rhamnose-glucose polymer (Rgp) as the definitive receptor for at least one problematic phage species. Detailed analysis of S. thermophilus rgp loci has revealed an unprecedented level of genetic diversity, particularly within the glycosyltransferase-encoding gene content of a given locus. Our study shows that this genetic diversity reflects the biochemical structure(s) of S. thermophilus Rgp. As such, we harnessed the genetic diversity of S. thermophilus rgp loci to develop a two-step multiplex PCR method for the classification of strain collections and, ultimately, the formation of phage-robust rational starter sets.
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12
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Disruption of the tagF Orthologue in the epa Locus Variable Region of Enterococcus faecalis Causes Cell Surface Changes and Suppresses an eep-Dependent Lysozyme Resistance Phenotype. J Bacteriol 2022; 204:e0024722. [PMID: 36094307 PMCID: PMC9578411 DOI: 10.1128/jb.00247-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The disease-producing capacity of the opportunistic pathogen Enterococcus faecalis is enhanced by the ability of the bacterium to evade killing by antimicrobial agents. Survival of E. faecalis in the presence of the human antimicrobial enzyme lysozyme is mediated in part by the site 2 metalloprotease Eep; however, a complete model of enterococcal lysozyme resistance has not been elucidated. To better understand the molecular basis for lysozyme resistance in E. faecalis, we analyzed Δeep suppressor mutants that acquire resistance to lysozyme through mutation of the gene OG1RF_11713, a predicted teichoic acid biosynthesis-encoding gene located within the variable region of the enterococcal polysaccharide antigen (epa) locus. Sequence comparisons revealed that OG1RF_11713 is most similar to the cytidine-5'-diphosphate (CDP)-glycerol:poly-(glycerolphosphate)glycerophosphotransferase TagF from Staphylococcus epidermidis. Inactivation of OG1RF_11713 in both the wild-type and Δeep genetic backgrounds was sufficient to increase the resistance of E. faecalis OG1RF to lysozyme. Minimal amounts of N-acetylgalactosamine were detectable in cell wall carbohydrate extracts of OG1RF_11713 deletion mutants, and this was associated with a reduction in negative cell surface charge. Targeted disruption of OG1RF_11713 was also associated with increased susceptibility to the antibiotic polymyxin B and membrane-targeting detergents and decreased susceptibility to the lantibiotic nisin. This work implicates OG1RF_11713 as a major determinant of cell envelope integrity and provides further validation that lysozyme resistance is intrinsically linked to the modification of enterococcal cell wall polysaccharides. IMPORTANCE Enterococcus faecalis is a leading cause of health-care-associated infections for which there are limited treatment options. E. faecalis is resistant to several antibiotics and to high concentrations of the human antimicrobial enzyme lysozyme. The molecular mechanisms that mediate lysozyme resistance in E. faecalis are complex and remain incompletely characterized. This work demonstrates that a gene located within the variable region of the enterococcal polysaccharide antigen locus of E. faecalis strain OG1RF (OG1RF_11713), which is predicted to encode a component of the teichoic acid biosynthesis machinery, is part of the lysozyme resistance circuitry and is important for enterococcal cell wall integrity. These findings suggest that OG1RF_11713 is a potential target for new therapeutic strategies to combat enterococcal infections.
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Guérin H, Kulakauskas S, Chapot-Chartier MP. Structural variations and roles of rhamnose-rich cell wall polysaccharides in Gram-positive bacteria. J Biol Chem 2022; 298:102488. [PMID: 36113580 PMCID: PMC9574508 DOI: 10.1016/j.jbc.2022.102488] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 09/08/2022] [Accepted: 09/10/2022] [Indexed: 11/17/2022] Open
Abstract
Rhamnose-rich cell wall polysaccharides (Rha-CWPSs) have emerged as crucial cell wall components of numerous Gram-positive, ovoid-shaped bacteria—including streptococci, enterococci, and lactococci—of which many are of clinical or biotechnological importance. Rha-CWPS are composed of a conserved polyrhamnose backbone with side-chain substituents of variable size and structure. Because these substituents contain phosphate groups, Rha-CWPS can also be classified as polyanionic glycopolymers, similar to wall teichoic acids, of which they appear to be functional homologs. Recent advances have highlighted the critical role of these side-chain substituents in bacterial cell growth and division, as well as in specific interactions between bacteria and infecting bacteriophages or eukaryotic hosts. Here, we review the current state of knowledge on the structure and biosynthesis of Rha-CWPS in several ovoid-shaped bacterial species. We emphasize the role played by multicomponent transmembrane glycosylation systems in the addition of side-chain substituents of various sizes as extracytoplasmic modifications of the polyrhamnose backbone. We provide an overview of the contribution of Rha-CWPS to cell wall architecture and biogenesis and discuss current hypotheses regarding their importance in the cell division process. Finally, we sum up the critical roles that Rha-CWPS can play as bacteriophage receptors or in escaping host defenses, roles that are mediated mainly through their side-chain substituents. From an applied perspective, increased knowledge of Rha-CWPS can lead to advancements in strategies for preventing phage infection of lactococci and streptococci in food fermentation and for combating pathogenic streptococci and enterococci.
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Affiliation(s)
- Hugo Guérin
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Saulius Kulakauskas
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
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Isolation, Partial Characterization and Application of Bacteriophages in Eradicating Biofilm Formation by Bacillus cereus on Stainless Steel Surfaces in Food Processing Facilities. Pathogens 2022; 11:pathogens11080872. [PMID: 36014993 PMCID: PMC9414048 DOI: 10.3390/pathogens11080872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/26/2022] [Accepted: 07/29/2022] [Indexed: 01/21/2023] Open
Abstract
The Bacillus cereus (B. cereus) group is a widespread foodborne pathogen with a persistent ability to form biofilm, and with inherent resistance to traditional treatment in the food industry. Bacteriophages are a promising biocontrol agent that could be applied to prevent or eliminate biofilms formation. We have described, in this study, the isolation from sewage samples and preliminary characterization of bacteriophages that are active against the B. cereus group. The effectiveness of phage treatment for reducing B. cereus attachment and biofilms on stainless steel surfaces has been also assessed using three incubation periods at different titrations of each phage. Out of 62 phages isolated, seven showed broad-spectrum lytic action against 174 B. cereus isolates. All selected phages appeared to be of the Siphoviridae family. SDS-PAGE proved that two phages have a similar profile, while the remainder are distinct. All isolated phages have the same restriction pattern, with an estimated genome size of around 37 kb. The isolated bacteriophages have been shown to be effective in preventing biofilm formation. Reductions of up to 1.5 log10 UFC/cm2 have been achieved, compared to the untreated biofilms. Curative treatment reduced the bacterial density by 0.5 log10 UFC/cm2. These results support the prospect of using these phages as a potential alternative strategy for controlling biofilms in food systems.
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Riu F, Ruda A, Ibba R, Sestito S, Lupinu I, Piras S, Widmalm G, Carta A. Antibiotics and Carbohydrate-Containing Drugs Targeting Bacterial Cell Envelopes: An Overview. Pharmaceuticals (Basel) 2022; 15:942. [PMID: 36015090 PMCID: PMC9414505 DOI: 10.3390/ph15080942] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/20/2022] [Accepted: 07/20/2022] [Indexed: 02/07/2023] Open
Abstract
Certain bacteria constitute a threat to humans due to their ability to escape host defenses as they easily develop drug resistance. Bacteria are classified into gram-positive and gram-negative according to the composition of the cell membrane structure. Gram-negative bacteria have an additional outer membrane (OM) that is not present in their gram-positive counterpart; the latter instead hold a thicker peptidoglycan (PG) layer. This review covers the main structural and functional properties of cell wall polysaccharides (CWPs) and PG. Drugs targeting CWPs are discussed, both noncarbohydrate-related (β-lactams, fosfomycin, and lipopeptides) and carbohydrate-related (glycopeptides and lipoglycopeptides). Bacterial resistance to these drugs continues to evolve, which calls for novel antibacterial approaches to be developed. The use of carbohydrate-based vaccines as a valid strategy to prevent bacterial infections is also addressed.
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Affiliation(s)
- Federico Riu
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy; (F.R.); (I.L.); (S.P.); (A.C.)
| | - Alessandro Ruda
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (G.W.)
| | - Roberta Ibba
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy; (F.R.); (I.L.); (S.P.); (A.C.)
| | - Simona Sestito
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy;
| | - Ilenia Lupinu
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy; (F.R.); (I.L.); (S.P.); (A.C.)
| | - Sandra Piras
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy; (F.R.); (I.L.); (S.P.); (A.C.)
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden; (A.R.); (G.W.)
| | - Antonio Carta
- Department of Medicine, Surgery and Pharmacy, University of Sassari, Via Muroni 23/A, 07100 Sassari, Italy; (F.R.); (I.L.); (S.P.); (A.C.)
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Antimicrobial tolerance and its role in the development of resistance: Lessons from enterococci. Adv Microb Physiol 2022; 81:25-65. [PMID: 36167442 DOI: 10.1016/bs.ampbs.2022.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bacteria have developed resistance against every antimicrobial in clinical use at an alarming rate. There is a critical need for more effective use of antimicrobials to both extend their shelf life and prevent resistance from arising. Significantly, antimicrobial tolerance, i.e., the ability to survive but not proliferate during antimicrobial exposure, has been shown to precede the development of bona fide antimicrobial resistance (AMR), sparking a renewed and rapidly increasing interest in this field. As a consequence, problematic infections for the first time are now being investigated for antimicrobial tolerance, with increasing reports demonstrating in-host evolution of antimicrobial tolerance. Tolerance has been identified in a wide array of bacterial species to all bactericidal antimicrobials. Of particular interest are enterococci, which contain the opportunistic bacterial pathogens Enterococcus faecalis and Enterococcus faecium. Enterococci are one of the leading causes of hospital-acquired infection and possess intrinsic tolerance to a number of antimicrobial classes. Persistence of these infections in the clinic is of growing concern, particularly for the immunocompromised. Here, we review current known mechanisms of antimicrobial tolerance, and include an in-depth analysis of those identified in enterococci with implications for both the development and prevention of AMR.
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Abstract
Phages that infect pathogenic bacteria present a valuable resource for treating antibiotic-resistant infections. We isolated and developed a collection of 19 Enterococcus phages, including myoviruses, siphoviruses, and a podovirus, that can infect both Enterococcus faecalis and Enterococcus faecium. Several of the Myoviridae phages that we found in southern California wastewater were from the Brockvirinae subfamily (formerly Spounavirinae) and had a broad host range across both E. faecium and E. faecalis. By searching the NCBI Sequence Read Archive, we showed that these phages are prevalent globally in human and animal microbiomes. Enterococcus is a regular member of healthy human gut microbial communities; however, it is also an opportunistic pathogen responsible for an increasing number of antibiotic-resistant infections. We tested the ability of each phage to clear Enterococcus host cultures and delay the emergence of phage-resistant Enterococcus. We found that some phages were ineffective at clearing Enterococcus cultures individually but were effective when combined into cocktails. Quantitative PCR was used to track phage abundance in cocultures and revealed dynamics ranging from one dominant phage to an even distribution of phage growth. Genomic characterization showed that mutations in Enterococcus exopolysaccharide synthesis genes were consistently found in the presence of phage infection. This work will help to inform cocktail design for Enterococcus, which is an important target for phage therapy applications. IMPORTANCE Due to the rise in antibiotic resistance, Enterococcus infections are a major health crisis that requires the development of alternative therapies. Phage therapy offers an alternative to antibiotics and has shown promise in both in vitro and early clinical studies. Here, we established a collection of 19 Enterococcus phages and tested whether combining phages into cocktails could delay growth and the emergence of resistant mutants in comparison with individual phages. We showed that cocktails of two or three phages often prevented the growth of phage-resistant mutants, and we identified which phages were replicating the most in each cocktail. When resistant mutants emerged to single phages, they showed consistent accumulation of mutations in exopolysaccharide synthesis genes. These data serve to demonstrate that a cocktail approach can inform efforts to improve efficacy against Enterococcus isolates and reduce the emergence of resistance.
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Ramos Y, Sansone S, Morales DK. Sugarcoating it: Enterococcal polysaccharides as key modulators of host-pathogen interactions. PLoS Pathog 2021; 17:e1009822. [PMID: 34499702 PMCID: PMC8428557 DOI: 10.1371/journal.ppat.1009822] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Yusibeska Ramos
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, New York, United States of America
| | - Stephanie Sansone
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, New York, United States of America
- Department of Urology, Weill Cornell Medicine, New York, New York, United States of America
| | - Diana K. Morales
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, New York, United States of America
- * E-mail:
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Lavelle K, Sinderen DV, Mahony J. Cell wall polysaccharides of Gram positive ovococcoid bacteria and their role as bacteriophage receptors. Comput Struct Biotechnol J 2021; 19:4018-4031. [PMID: 34377367 PMCID: PMC8327497 DOI: 10.1016/j.csbj.2021.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/12/2021] [Accepted: 07/12/2021] [Indexed: 11/23/2022] Open
Abstract
Gram-positive bacterial cell walls are characterised by the presence of a thick peptidoglycan layer which provides protection from extracellular stresses, maintains cell integrity and determines cell morphology, while it also serves as a foundation to anchor a number of crucial polymeric structures. For ovococcal species, including streptococci, enterococci and lactococci, such structures are represented by rhamnose-containing cell wall polysaccharides, which at least in some instances appear to serve as a functional replacement for wall teichoic acids. The biochemical composition of several streptococcal, lactococcal and enterococcal rhamnose-containing cell wall polysaccharides have been elucidated, while associated functional genomic analyses have facilitated the proposition of models for individual biosynthetic pathways. Here, we review the genomic loci which encode the enzymatic machinery to produce rhamnose-containing, cell wall-associated polysaccharide (Rha cwps) structures of the afore-mentioned ovococcal bacteria with particular emphasis on gene content, biochemical structure and common biosynthetic steps. Furthermore, we discuss the role played by these saccharidic polymers as receptors for bacteriophages and the important role phages play in driving Rha cwps diversification and evolution.
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Affiliation(s)
- Katherine Lavelle
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
| | - Douwe van Sinderen
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
| | - Jennifer Mahony
- School of Microbiology & APC Microbiome Ireland, University College Cork, Western Road, Cork T12 YT20, Ireland
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20
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Fatoba AJ, Adeleke VT, Maharaj L, Okpeku M, Adeniyi AA, Adeleke MA. Immunoinformatics Design of Multiepitope Vaccine Against Enterococcus faecium Infection. Int J Pept Res Ther 2021. [DOI: 10.1007/s10989-021-10245-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Comparative Biofilm Assays Using Enterococcus faecalis OG1RF Identify New Determinants of Biofilm Formation. mBio 2021; 12:e0101121. [PMID: 34126766 PMCID: PMC8262879 DOI: 10.1128/mbio.01011-21] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Enterococcus faecalis is a common commensal organism and a prolific nosocomial pathogen that causes biofilm-associated infections. Numerous E. faecalis OG1RF genes required for biofilm formation have been identified, but few studies have compared genetic determinants of biofilm formation and biofilm morphology across multiple conditions. Here, we cultured transposon (Tn) libraries in CDC biofilm reactors in two different media and used Tn sequencing (TnSeq) to identify core and accessory biofilm determinants, including many genes that are poorly characterized or annotated as hypothetical. Multiple secondary assays (96-well plates, submerged Aclar discs, and MultiRep biofilm reactors) were used to validate phenotypes of new biofilm determinants. We quantified biofilm cells and used fluorescence microscopy to visualize biofilms formed by six Tn mutants identified using TnSeq and found that disrupting these genes (OG1RF_10350, prsA, tig, OG1RF_10576, OG1RF_11288, and OG1RF_11456) leads to significant time- and medium-dependent changes in biofilm architecture. Structural predictions revealed potential roles in cell wall homeostasis for OG1RF_10350 and OG1RF_11288 and signaling for OG1RF_11456. Additionally, we identified growth medium-specific hallmarks of OG1RF biofilm morphology. This study demonstrates how E. faecalis biofilm architecture is modulated by growth medium and experimental conditions and identifies multiple new genetic determinants of biofilm formation.
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22
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Inactivation of GalU Leads to a Cell Wall-Associated Polysaccharide Defect That Reduces the Susceptibility of Enterococcus faecalis to Bacteriolytic Agents. Appl Environ Microbiol 2021; 87:AEM.02875-20. [PMID: 33483312 DOI: 10.1128/aem.02875-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/13/2021] [Indexed: 12/11/2022] Open
Abstract
Enterococcal plasmid-encoded bacteriolysin Bac41 is a selective antimicrobial system that is considered to provide a competitive advantage to Enterococcus faecalis cells that carry the Bac41-coding plasmid. The Bac41 effector consists of the secreted proteins BacL1 and BacA, which attack the cell wall of the target E. faecalis cell to induce bacteriolysis. Here, we demonstrated that galU, which encodes UTP-glucose-1-phosphate uridylyltransferase, is involved in susceptibility to the Bac41 system in E. faecalis Spontaneous mutants that developed resistance to the antimicrobial effects of BacL1 and BacA were revealed to carry a truncation deletion of the C-terminal amino acid (aa) region 288 to 298 of the translated GalU protein. This truncation resulted in the depletion of UDP-glucose, leading to a failure to utilize galactose and produce the enterococcal polysaccharide antigen (EPA), which is expressed abundantly on the cell surface of E. faecalis This cell surface composition defect that resulted from galU or EPA-specific genes caused an abnormal cell morphology, with impaired polarity during cell division and alterations of the limited localization of BacL1 Interestingly, these mutants had reduced susceptibility to beta-lactams besides Bac41, despite their increased susceptibility to other bacteriostatic antimicrobial agents and chemical detergents. These data suggest that a complex mechanism of action underlies lytic killing, as exogenous bacteriolysis induced by lytic bacteriocins or beta-lactams requires an intact cell physiology in E. faecalis IMPORTANCE Cell wall-associated polysaccharides of bacteria are involved in various physiological characteristics. Recent studies demonstrated that the cell wall-associated polysaccharide of Enterococcus faecalis is required for susceptibility to bactericidal antibiotic agents. Here, we demonstrated that a galU mutation resulted in resistance to the enterococcal lytic bacteriocin Bac41. The galU homologue is reported to be essential for the biosynthesis of species-specific cell wall-associated polysaccharides in other Firmicutes In E. faecalis, the galU mutant lost the E. faecalis-specific cell wall-associated polysaccharide EPA (enterococcal polysaccharide antigen). The mutant also displayed reduced susceptibility to antibacterial agents and an abnormal cell morphology. We demonstrated here that galU was essential for EPA biosynthesis in E. faecalis, and EPA production might underlie susceptibility to lytic bacteriocin and antibiotic agents by undefined mechanisms.
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23
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North OI, Brown ED. Phage-antibiotic combinations: a promising approach to constrain resistance evolution in bacteria. Ann N Y Acad Sci 2020; 1496:23-34. [PMID: 33175408 DOI: 10.1111/nyas.14533] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/15/2020] [Accepted: 10/26/2020] [Indexed: 12/18/2022]
Abstract
Antibiotic resistance has reached dangerously high levels throughout the world. A growing number of bacteria pose an urgent, serious, and concerning threat to public health. Few new antibiotics are available to clinicians and only few are in development, highlighting the need for new strategies to overcome the antibiotic resistance crisis. Combining existing antibiotics with phages, viruses the infect bacteria, is an attractive and promising alternative to standalone therapies. Phage-antibiotic combinations have been shown to suppress the emergence of resistance in bacteria, and sometimes even reverse it. Here, we discuss the mechanisms by which phage-antibiotic combinations reduce resistance evolution, and the potential limitations these mechanisms have in steering microbial resistance evolution in a desirable direction. We also emphasize the importance of gaining a better understanding of mechanisms behind physiological and evolutionary phage-antibiotic interactions in complex in-patient environments.
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Affiliation(s)
- Olesia I North
- Department of Biochemistry and Biomedical Sciences and M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Ontario, Canada
| | - Eric D Brown
- Department of Biochemistry and Biomedical Sciences and M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Ontario, Canada
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24
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Zhang H, Stevens RH. Intrinsic resistance of Enterococcus faecalis strains to ΦEf11 phage endolysin is associated with the presence of ΦEf11 prophage. Arch Virol 2020; 166:249-258. [PMID: 33165649 DOI: 10.1007/s00705-020-04861-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/15/2020] [Indexed: 02/07/2023]
Abstract
The use of bacteriophage-encoded murein hydrolases (endolysins) is being actively explored as a means of controlling multidrug-resistant pathogens. Previously, we isolated and characterized one such enzyme, the phage ΦEf11 ORF28 lysin, which demonstrated profound antimicrobial activity against many strains of Enterococcus faecalis. Although the lysin is eminently active against many vancomycin-resistant enterococal (VRE) strains, and displays lower minimum inhibitory concentrations than vancomycin against vancomycin-sensitive strains, there is a subset of E. faecalis strains that is not affected by the lysin. Currently, there is no explanation for the disparate sensitivity to ORF28 lysin among E. faecalis strains. In the present investigation, we show that the intrinsic insensitivity of the insusceptible strains to the lysin is associated with the presence of a ΦEf11 prophage. Of the strains harboring phage ΦEf11 genes (N = 28), 68% were insensitive to the lysin, whereas 91% of the strains (N = 75) lacking detectable ΦEf11 genes demonstrated lysin sensitivity. Furthermore, curing a lysin-resistant, lysogenic E. faecalis strain resulted in a lysin-sensitive derivative, whereas lysogenizing a wild-type non-lysogenic strain converted it from lysin sensitivity to lysin resistance. Our results suggest that lysin resistance comes about through lysogenic conversion of non-lysogenic, lysin-sensitive strains.
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Affiliation(s)
- Hongming Zhang
- Laboratory of Oral Infectious Diseases, Kornberg School of Dentistry, Temple University, Philadelphia, PA, 19140, USA
| | - Roy H Stevens
- Laboratory of Oral Infectious Diseases, Kornberg School of Dentistry, Temple University, Philadelphia, PA, 19140, USA.
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Kalfopoulou E, Huebner J. Advances and Prospects in Vaccine Development against Enterococci. Cells 2020; 9:cells9112397. [PMID: 33147722 PMCID: PMC7692742 DOI: 10.3390/cells9112397] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 12/26/2022] Open
Abstract
Enterococci are the second most common Gram-positive pathogen responsible for nosocomial infections. Due to the limited number of new antibiotics that reach the medical practice and the resistance of enterococci to the current antibiotic options, passive and active immunotherapies have emerged as a potential prevention and/or treatment strategy against this opportunistic pathogen. In this review, we explore the pathogenicity of these bacteria and their interaction with the host immune response. We provide an overview of the capsular polysaccharides and surface-associated proteins that have been described as potential antigens in anti-enterococcal vaccine formulations. In addition, we describe the current status in vaccine development against enterococci and address the importance and the current advances toward the development of well-defined vaccines with broad coverage against enterococci.
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Affiliation(s)
- Ermioni Kalfopoulou
- Institute for Medical Microbiology, Immunology and Hygiene, Technical University of Munich, 81675 Munich, Germany;
| | - Johannes Huebner
- Division of Paediatric Infectious Diseases, Dr. von Hauner Children’s Hospital, Ludwig Maximilians University, 80337 Munich, Germany
- Correspondence: ; Tel.: +49-89-44005-7970
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A comprehensive review of bacterial osteomyelitis with emphasis on Staphylococcus aureus. Microb Pathog 2020; 148:104431. [PMID: 32801004 DOI: 10.1016/j.micpath.2020.104431] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 02/04/2023]
Abstract
Osteomyelitis, a significant infection of bone tissue, gives rise to two main groups of infection: acute and chronic. These groups are further categorized in terms of the duration of infection. Usually, children and adults are more susceptible to acute and chronic infections, respectively. The aforementioned groups of osteomyelitis share almost 80% of the corresponding bacterial pathogens. Among all bacteria, Staphylococcus aureus (S. aureus) is a significant pathogen and is associated with a high range of osteomyelitis symptoms. S. aureus has many strategies for interacting with host cells including Small Colony Variant (SCV), biofilm formation, and toxin secretion. In addition, it induces an inflammatory response and causes host cell death by apoptosis and necrosis. However, any possible step to take in this respect is dependent on the conditions and host responses. In the absence of any immune responses and antibiotics, bacteria actively duplicate themselves; however, in the presence of phagocytic cell and harassing conditions, they turn into a SCV, remaining sustainable for a long time. SCV is characterized by notable advantages such as (a) intracellular life that mediates a dam against immune cells and (b) low ATP production that mediates resistance against antibiotics.
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27
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Brown AO, Singh KV, Cruz MR, Kaval KG, Francisco LE, Murray BE, Garsin DA. Cardiac Microlesions Form During Severe Bacteremic Enterococcus faecalis Infection. J Infect Dis 2020; 223:508-516. [PMID: 32597945 DOI: 10.1093/infdis/jiaa371] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 06/22/2020] [Indexed: 12/22/2022] Open
Abstract
Enterococcus faecalis is a significant cause of hospital-acquired bacteremia. Herein, the discovery is reported that cardiac microlesions form during severe bacteremic E. faecalis infection in mice. The cardiac microlesions were identical in appearance to those formed by Streptococcus pneumoniae during invasive pneumococcal disease. However, E. faecalis does not encode the virulence determinants implicated in pneumococcal microlesion formation. Rather, disulfide bond forming protein A (DsbA) was found to be required for E. faecalis virulence in a Caenorhabditis elegans model and was necessary for efficient cardiac microlesion formation. Furthermore, E. faecalis promoted cardiomyocyte apoptotic and necroptotic cell death at sites of microlesion formation. Additionally, loss of DsbA caused an increase in proinflammatory cytokines, unlike the wild-type strain, which suppressed the immune response. In conclusion, we establish that E. faecalis is capable of forming cardiac microlesions and identify features of both the bacterium and the host response that are mechanistically involved.
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Affiliation(s)
- Armand O Brown
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Kavindra V Singh
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Melissa R Cruz
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Karan Gautam Kaval
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Liezl E Francisco
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Barbara E Murray
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA.,Division of Infectious Diseases, Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Danielle A Garsin
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, USA
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Mangalea MR, Duerkop BA. Fitness Trade-Offs Resulting from Bacteriophage Resistance Potentiate Synergistic Antibacterial Strategies. Infect Immun 2020; 88:e00926-19. [PMID: 32094257 PMCID: PMC7309606 DOI: 10.1128/iai.00926-19] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Bacteria that cause life-threatening infections in humans are becoming increasingly difficult to treat. In some instances, this is due to intrinsic and acquired antibiotic resistance, indicating that new therapeutic approaches are needed to combat bacterial pathogens. There is renewed interest in utilizing viruses of bacteria known as bacteriophages (phages) as potential antibacterial therapeutics. However, critics suggest that similar to antibiotics, the development of phage-resistant bacteria will halt clinical phage therapy. Although the emergence of phage-resistant bacteria is likely inevitable, there is a growing body of literature showing that phage selective pressure promotes mutations in bacteria that allow them to subvert phage infection, but with a cost to their fitness. Such fitness trade-offs include reduced virulence, resensitization to antibiotics, and colonization defects. Resistance to phage nucleic acid entry, primarily via cell surface modifications, compromises bacterial fitness during antibiotic and host immune system pressure. In this minireview, we explore the mechanisms behind phage resistance in bacterial pathogens and the physiological consequences of acquiring phage resistance phenotypes. With this knowledge, it may be possible to use phages to alter bacterial populations, making them more tractable to current therapeutic strategies.
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Affiliation(s)
- Mihnea R Mangalea
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Breck A Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
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Van Tyne D, Manson AL, Huycke MM, Karanicolas J, Earl AM, Gilmore MS. Impact of antibiotic treatment and host innate immune pressure on enterococcal adaptation in the human bloodstream. Sci Transl Med 2020; 11:11/487/eaat8418. [PMID: 30971455 DOI: 10.1126/scitranslmed.aat8418] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 11/10/2018] [Indexed: 12/11/2022]
Abstract
Multidrug-resistant enterococcal strains emerged in the early 1980s and are now among the leading causes of drug-resistant bacterial infection worldwide. We used functional genomics to study an early bacterial outbreak in patients in a Wisconsin hospital between 1984 and 1988 that was caused by multidrug-resistant Enterococcus faecalis The goal was to determine how a clonal lineage of E. faecalis became adapted to growth and survival in the human bloodstream. Genome sequence analysis revealed a progression of increasingly fixed mutations and repeated independent occurrences of mutations in a relatively small set of genes. Repeated independent mutations suggested selection within the host during the course of infection in response to pressures such as host immunity and antibiotic treatment. We observed repeated independent mutations in a small number of loci, including a little studied polysaccharide utilization pathway and the cydABDC locus. Functional studies showed that mutating these loci rendered E. faecalis better able to withstand antibiotic pressure and innate immune defenses in the human bloodstream. We also observed a shift in mutation pattern that corresponded to the introduction of carbapenem antibiotics in 1987. This work identifies pathways that allow enterococci to survive the transition from the human gut into the bloodstream, enabling them to cause severe bacteremia associated with high mortality.
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Affiliation(s)
- Daria Van Tyne
- Department of Ophthalmology and Department of Microbiology, Harvard Medical School, Boston, MA 02114, USA.,Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.,Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Abigail L Manson
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Mark M Huycke
- Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Ashlee M Earl
- Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
| | - Michael S Gilmore
- Department of Ophthalmology and Department of Microbiology, Harvard Medical School, Boston, MA 02114, USA. .,Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.,Infectious Disease and Microbiome Program, Broad Institute, Cambridge, MA 02142, USA
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Complete Structure of the Enterococcal Polysaccharide Antigen (EPA) of Vancomycin-Resistant Enterococcus faecalis V583 Reveals that EPA Decorations Are Teichoic Acids Covalently Linked to a Rhamnopolysaccharide Backbone. mBio 2020; 11:mBio.00277-20. [PMID: 32345640 PMCID: PMC7188991 DOI: 10.1128/mbio.00277-20] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Enterococci are opportunistic pathogens responsible for hospital- and community-acquired infections. All enterococci produce a surface polysaccharide called EPA (enterococcal polysaccharide antigen) required for biofilm formation, antibiotic resistance, and pathogenesis. Despite the critical role of EPA in cell growth and division and as a major virulence factor, no information is available on its structure. Here, we report the complete structure of the EPA polymer produced by the model strain E. faecalis V583. We describe the structure of the EPA backbone, made of a rhamnan hexasaccharide substituted by Glc and GlcNAc residues, and show that teichoic acids are covalently bound to this rhamnan chain, forming the so-called “EPA decorations” essential for host colonization and pathogenesis. This report represents a key step in efforts to identify the structural properties of EPA that are essential for its biological activity and to identify novel targets to develop preventive and therapeutic approaches against enterococci. All enterococci produce a complex polysaccharide called the enterococcal polysaccharide antigen (EPA). This polymer is required for normal cell growth and division and for resistance to cephalosporins and plays a critical role in host-pathogen interaction. The EPA contributes to host colonization and is essential for virulence, conferring resistance to phagocytosis during the infection. Recent studies revealed that the “decorations” of the EPA polymer, encoded by genetic loci that are variable between isolates, underpin the biological activity of this surface polysaccharide. In this work, we investigated the structure of the EPA polymer produced by the high-risk enterococcal clonal complex Enterococcus faecalis V583. We analyzed purified EPA from the wild-type strain and a mutant lacking decorations and elucidated the structure of the EPA backbone and decorations. We showed that the rhamnan backbone of EPA is composed of a hexasaccharide repeat unit of C2- and C3-linked rhamnan chains, partially substituted in the C3 position by α-glucose (α-Glc) and in the C2 position by β-N-acetylglucosamine (β-GlcNAc). The so-called “EPA decorations” consist of phosphopolysaccharide chains corresponding to teichoic acids covalently bound to the rhamnan backbone. The elucidation of the complete EPA structure allowed us to propose a biosynthetic pathway, a first essential step toward the design of antimicrobials targeting the synthesis of this virulence factor.
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Freitas AR, Tedim AP, Novais C, Lanza VF, Peixe L. Comparative genomics of global optrA-carrying Enterococcus faecalis uncovers a common chromosomal hotspot for optrA acquisition within a diversity of core and accessory genomes. Microb Genom 2020; 6. [PMID: 32149599 PMCID: PMC7371108 DOI: 10.1099/mgen.0.000350] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Linezolid-resistant Enterococcus faecalis (LREfs) carrying optrA are increasingly reported globally from multiple sources, but we lack a comprehensive analysis of human and animal optrA-LREfs strains. To assess if optrA is dispersed in isolates with varied genetic backgrounds or with common genetic features, we investigated the phylogenetic structure, genetic content [antimicrobial resistance (AMR), virulence, prophages, plasmidome] and optrA-containing platforms of 27 publicly available optrA-positive E. faecalis genomes from different hosts in seven countries. At the genome-level analysis, an in-house database with 64 virulence genes was tested for the first time. Our analysis showed a diversity of clones and adaptive gene sequences related to a wide range of genera from Firmicutes. Phylogenies of core and accessory genomes were not congruent, and at least PAI-associated and prophage genes contribute to such differences. Epidemiologically unrelated clones (ST21, ST476-like and ST489) obtained from human clinical and animal hosts in different continents over eight years (2010–2017) could be phylogenetically related (3–126 SNPs difference). optrA was located on the chromosome within a Tn6674-like element (n=10) or on medium-size plasmids (30–60 kb; n=14) belonging to main plasmid families (RepA_N/Inc18/Rep_3). In most cases, the immediate gene vicinity of optrA was generally identical in chromosomal (Tn6674) or plasmid (impB-fexA-optrA) backbones. Tn6674 was always inserted into the same ∆radC integration site and embedded in a 32 kb chromosomal platform common to strains from different origins (patients, healthy humans, and animals) in Europe, Africa, and Asia during 2012–2017. This platform is conserved among hundreds of E. faecalis genomes and proposed as a chromosomal hotspot for optrA integration. The finding of optrA in strains sharing common adaptive features and genetic backgrounds across different hosts and countries suggests the occurrence of common and independent genetic events occurring in distant regions and might explain the easy de novo generation of optrA-positive strains. It also anticipates a dramatic increase of optrA carriage and spread with a serious impact on the efficacy of linezolid for the treatment of Gram-positive infections.
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Affiliation(s)
- Ana R Freitas
- UCIBIO/REQUIMTE. Departamento de Ciências Biológicas. Laboratório de Microbiologia. Faculdade de Farmácia. Universidade do Porto. Porto, Porto, Portugal
| | - Ana P Tedim
- Grupo de Investigación Biomédica en Sepsis - BioSepsis. Hospital Universitario Río Hortega, Instituto de Investigación Biomédica de Salamanca (IBSAL), Valladollid, Spain
| | - Carla Novais
- UCIBIO/REQUIMTE. Departamento de Ciências Biológicas. Laboratório de Microbiologia. Faculdade de Farmácia. Universidade do Porto. Porto, Porto, Portugal
| | - Val F Lanza
- Departamento de Bioinformática. Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
| | - Luísa Peixe
- UCIBIO/REQUIMTE. Departamento de Ciências Biológicas. Laboratório de Microbiologia. Faculdade de Farmácia. Universidade do Porto. Porto, Porto, Portugal
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Abstract
We lack fundamental understanding of how phage infection influences bacterial gene expression and, consequently, how bacterial responses to phage infection affect the assembly of polymicrobial communities. Using parallel genomic approaches, we have discovered novel transcriptional regulators and metabolic genes that influence phage infection. The integration of whole-genome transcriptomic profiling during phage infection has revealed the differential regulation of genes important for group behaviors and polymicrobial interactions. Our work suggests that therapeutic phages could more broadly influence bacterial community composition outside their intended host targets. Bacteriophages (phages) have been proposed as alternative therapeutics for the treatment of multidrug-resistant bacterial infections. However, there are major gaps in our understanding of the molecular events in bacterial cells that control how bacteria respond to phage predation. Using the model organism Enterococcus faecalis, we used two distinct genomic approaches, namely, transposon library screening and RNA sequencing, to investigate the interaction of E. faecalis with a virulent phage. We discovered that a transcription factor encoding a LytR family response regulator controls the expression of enterococcal polysaccharide antigen (epa) genes that are involved in phage infection and bacterial fitness. In addition, we discovered that DNA mismatch repair mutants rapidly evolve phage adsorption deficiencies, underpinning a molecular basis for epa mutation during phage infection. Transcriptomic profiling of phage-infected E. faecalis revealed broad transcriptional changes influencing viral replication and progeny burst size. We also demonstrate that phage infection alters the expression of bacterial genes associated with intra- and interbacterial interactions, including genes involved in quorum sensing and polymicrobial competition. Together, our results suggest that phage predation has the potential to influence complex microbial behavior and may dictate how bacteria respond to external environmental stimuli. These responses could have collateral effects (positive or negative) on microbial communities, such as the host microbiota, during phage therapy.
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Identification of Novel Bacteriophages with Therapeutic Potential That Target Enterococcus faecalis. Infect Immun 2019; 87:IAI.00512-19. [PMID: 31451618 PMCID: PMC6803325 DOI: 10.1128/iai.00512-19] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 08/13/2019] [Indexed: 12/14/2022] Open
Abstract
The Gram-positive opportunistic pathogen Enterococcus faecalis is frequently responsible for nosocomial infections in humans and represents one of the most common bacteria isolated from recalcitrant endodontic (root canal) infections. E. faecalis is intrinsically resistant to several antibiotics routinely used in clinical settings (such as cephalosporins and aminoglycosides) and can acquire resistance to vancomycin (vancomycin-resistant enterococci). The resistance of E. faecalis to several classes of antibiotics and its capacity to form biofilms cause serious therapeutic problems. Here, we report the isolation of several bacteriophages that target E. faecalis strains isolated from the oral cavity of patients suffering root canal infections. All phages isolated were Siphoviridae with similar tail lengths (200 to 250 nm) and icosahedral heads. The genome sequences of three isolated phages were highly conserved with the exception of predicted tail protein genes that diverge in sequence, potentially reflecting the host range. The properties of the phage with the broadest host range (SHEF2) were further characterized. We show that this phage requires interaction with components of the major and variant region enterococcal polysaccharide antigen to engage in lytic infection. Finally, we explored the therapeutic potential of this phage and show that it can eradicate E. faecalis biofilms formed in vitro on a standard polystyrene surface but also on a cross-sectional tooth slice model of endodontic infection. We also show that SHEF2 cleared a lethal infection of zebrafish when applied in the circulation. We therefore propose that the phage described here could be used to treat a broad range of antibiotic-resistant E. faecalis infections.
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Ramos Y, Morales DK. Exopolysaccharide-mediated surface penetration as new virulence trait in Enterococcus faecalis. Commun Integr Biol 2019; 12:144-147. [PMID: 31666914 PMCID: PMC6802913 DOI: 10.1080/19420889.2019.1657373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/15/2019] [Indexed: 11/07/2022] Open
Abstract
Enterococcus faecalis is a commensal bacterium that normally inhabits the gastrointestinal tract of humans. This non-motile microorganism can also cause lethal infections in other organs by penetrating and breaching the intestinal barrier. However, the precise molecular mechanisms enabling E. faecalis movement and translocation across epithelial barriers remain incompletely characterized. We recently reported that E. faecalis utilizes the RpiA-GlnA-EpaX metabolic axis to generate β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc)-containing exopolymers that are necessary for its optimal migration into semisolid surfaces and efficient translocation through human epithelial cell monolayers. These findings provide new evidence indicating that non-motile bacterial pathogens can exploit carbohydrate metabolism to penetrate surfaces. Hence, targeting this process might represent a new strategy to more effectively control systemic infections by E. faecalis.
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Affiliation(s)
- Yusibeska Ramos
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, USA
| | - Diana K Morales
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, USA
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Role of epaQ, a Previously Uncharacterized Enterococcus faecalis Gene, in Biofilm Development and Antimicrobial Resistance. J Bacteriol 2019; 201:JB.00078-19. [PMID: 30910809 DOI: 10.1128/jb.00078-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/15/2019] [Indexed: 12/31/2022] Open
Abstract
Enterococcus faecalis is a commensal of the human gastrointestinal tract; it is also an opportunistic pathogen and one of the leading causes of hospital-acquired infections. E. faecalis produces biofilms that are highly resistant to antibiotics, and it has been previously reported that certain genes of the epa operon contribute to biofilm-associated antibiotic resistance. Despite several studies examining the epa operon, many gene products of this operon remain annotated as hypothetical proteins. Here, we further explore the epa operon; we identified epaQ, currently annotated as encoding a hypothetical membrane protein, as being important for biofilm formation in the presence of the antibiotic daptomycin. Mutants with disruptions of epaQ were more susceptible to daptomycin relative to the wild type, suggesting its importance in biofilm-associated antibiotic resistance. Furthermore, the ΔepaQ mutant exhibited an altered biofilm architectural arrangement and formed small aggregates in liquid cultures. Our cumulative data show that epa mutations result in altered polysaccharide content, increased cell surface hydrophobicity, and decreased membrane potential. Surprisingly, several epa mutations significantly increased resistance to the antibiotic ceftriaxone, indicating that the way in which the epa operon impacts antibiotic resistance is antibiotic dependent. These results further define the key role of epa in antibiotic resistance in biofilms and in biofilm architecture.IMPORTANCE E. faecalis is a common cause of nosocomial infection, has a high level of antibiotic resistance, and forms robust biofilms. Biofilm formation is associated with increased antibiotic resistance. Therefore, a thorough understanding of biofilm-associated antibiotic resistance is important for combating resistance. Several genes from the epa operon have previously been implicated in biofilm-associated antibiotic resistance, pathogenesis, and competitive fitness in the GI tract, but most genes in this locus remain uncharacterized. Here, we examine epaQ, which has not been characterized functionally. We show that the ΔepaQ mutant exhibits reduced biofilm formation in the presence of daptomycin, altered biofilm architecture, and increased resistance to ceftriaxone, further expanding our understanding of the contribution of this operon to intrinsic enterococcal antibiotic resistance and biofilm growth.
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Fitness Restoration of a Genetically Tractable Enterococcus faecalis V583 Derivative To Study Decoration-Related Phenotypes of the Enterococcal Polysaccharide Antigen. mSphere 2019; 4:4/4/e00310-19. [PMID: 31292230 PMCID: PMC6620374 DOI: 10.1128/msphere.00310-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
E. faecalis strain VE14089 was derived from V583 cured of its plasmids. Although VE14089 had no major DNA rearrangements, it presented significant growth and host adaptation differences from the reference strain V583 of our collection. To construct a strain with better fitness, we sequenced the genome of VE14089, identified single nucleotide polymorphisms (SNPs), and repaired the genes that could account for these changes. Using this reference-derivative strain, we provide a novel genetic system to understand the role of the variable region of epa in the enterococcal lifestyle. Commensal and generally harmless in healthy individuals, Enterococcus faecalis causes opportunistic infections in immunocompromised patients. Plasmid-cured E. faecalis strain VE14089, derived from sequenced reference strain V583, is widely used for functional studies due to its improved genetic amenability. Although strain VE14089 has no major DNA rearrangements, with the exception of an ∼20-kb integrated region of pTEF1 plasmid, the strain presented significant growth differences from the V583 reference strain of our collection (renamed VE14002). In the present study, genome sequencing of strain VE14089 identified additional point mutations. Excision of the integrated pTEF1 plasmid region and sequential restoration of wild-type alleles showing nonsilent mutations were performed to obtain the VE18379 reference-derivative strain. Recovery of the growth ability of the restored VE18379 strain at a level similar to that seen with the reference strain points to GreA and Spx as bacterial fitness determinants. Virulence potential in Galleria mellonella and intestinal colonization in mouse demonstrated host adaptation of the VE18379 strain equivalent to VE14002 host adaptation. We further demonstrated that deletion of the 16.8-kb variable region of the epa locus recapitulates the key role of Epa decoration in host adaptation, providing a genetic system to study the role of specific epa-variable regions in host adaptation independently of other genetic variations. IMPORTANCEE. faecalis strain VE14089 was derived from V583 cured of its plasmids. Although VE14089 had no major DNA rearrangements, it presented significant growth and host adaptation differences from the reference strain V583 of our collection. To construct a strain with better fitness, we sequenced the genome of VE14089, identified single nucleotide polymorphisms (SNPs), and repaired the genes that could account for these changes. Using this reference-derivative strain, we provide a novel genetic system to understand the role of the variable region of epa in the enterococcal lifestyle.
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Suryaletha K, Narendrakumar L, John J, Radhakrishnan MP, George S, Thomas S. Decoding the proteomic changes involved in the biofilm formation of Enterococcus faecalis SK460 to elucidate potential biofilm determinants. BMC Microbiol 2019; 19:146. [PMID: 31253082 PMCID: PMC6599329 DOI: 10.1186/s12866-019-1527-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/20/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Enterococcus faecalis is a major clinically relevant nosocomial bacterial pathogen frequently isolated from polymicrobial infections. The biofilm forming ability of E. faecalis attributes a key role in its virulence and drug resistance. Biofilm cells are phenotypically and metabolically different from their planktonic counterparts and many aspects involved in E. faecalis biofilm formation are yet to be elucidated. The strain E. faecalis SK460 used in the present study is esp (Enterococcal surface protein) and fsr (two-component signal transduction system) negative non-gelatinase producing strong biofilm former isolated from a chronic diabetic foot ulcer patient. We executed a label-free quantitative proteomic approach to elucidate the differential protein expression pattern at planktonic and biofilm stages of SK460 to come up with potential determinants associated with Enterococcal biofilm formation. RESULTS The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of proteomic data revealed that biofilm cells expressed higher levels of proteins which are associated with glycolysis, amino acid biosynthesis, biosynthesis of secondary metabolites, microbial metabolism in diverse environments and stress response factors. Besides these basic survival pathways, LuxS-mediated quorum sensing, arginine metabolism, rhamnose biosynthesis, pheromone and adhesion associated proteins were found to be upregulated during the biofilm transit from planktonic stages. The selected subsets were validated by quantitative real-time PCR. In silico functional interaction analysis revealed that the genes involved in upregulated pathways pose a close molecular interaction thereby coordinating the regulatory network to thrive as a biofilm community. CONCLUSIONS The present study describes the first report of the quantitative proteome analysis of an esp and fsr negative non gelatinase producing E. faecalis. Proteome analysis evidenced enhanced expression of glycolytic pathways, stress response factors, LuxS quorum signaling system, rhamnopolysaccharide synthesis and pheromone associated proteins in biofilm phenotype. We also pointed out the relevance of LuxS quorum sensing and pheromone associated proteins in the biofilm development of E. faecalis which lacks the Fsr quorum signaling system. These validated biofilm determinants can act as potential inhibiting targets in Enterococcal infections.
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Affiliation(s)
- Karthika Suryaletha
- Cholera and Biofilm Research Laboratory, Pathogen Biology, Rajiv Gandhi Centre for Biotechnology, (National Institute under the Department of Biotechnology, Government of India), Trivandrum, Kerala, 695014, India
| | - Lekshmi Narendrakumar
- Cholera and Biofilm Research Laboratory, Pathogen Biology, Rajiv Gandhi Centre for Biotechnology, (National Institute under the Department of Biotechnology, Government of India), Trivandrum, Kerala, 695014, India
| | - Joby John
- Department of Surgery, Government Medical College Hospital, Trivandrum, Kerala, 695011, India
| | - Megha Periyappilly Radhakrishnan
- Cholera and Biofilm Research Laboratory, Pathogen Biology, Rajiv Gandhi Centre for Biotechnology, (National Institute under the Department of Biotechnology, Government of India), Trivandrum, Kerala, 695014, India
| | - Sanil George
- Interdisciplinary Biology, Rajiv Gandhi Centre for Biotechnology, Trivandrum, Kerala, 695014, India
| | - Sabu Thomas
- Cholera and Biofilm Research Laboratory, Pathogen Biology, Rajiv Gandhi Centre for Biotechnology, (National Institute under the Department of Biotechnology, Government of India), Trivandrum, Kerala, 695014, India.
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Bacteriophage Resistance Alters Antibiotic-Mediated Intestinal Expansion of Enterococci. Infect Immun 2019; 87:IAI.00085-19. [PMID: 30936157 DOI: 10.1128/iai.00085-19] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/25/2019] [Indexed: 12/11/2022] Open
Abstract
Enterococcus faecalis is a human intestinal pathobiont with intrinsic and acquired resistance to many antibiotics, including vancomycin. Nature provides a diverse and virtually untapped repertoire of bacterial viruses, or bacteriophages (phages), that could be harnessed to combat multidrug-resistant enterococcal infections. Bacterial phage resistance represents a potential barrier to the implementation of phage therapy, emphasizing the importance of investigating the molecular mechanisms underlying the emergence of phage resistance. Using a cohort of 19 environmental lytic phages with tropism against E. faecalis, we found that these phages require the enterococcal polysaccharide antigen (Epa) for productive infection. Epa is a surface-exposed heteroglycan synthesized by enzymes encoded by both conserved and strain-specific genes. We discovered that exposure to phage selective pressure favors mutation in nonconserved epa genes both in culture and in a mouse model of intestinal colonization. Despite gaining phage resistance, epa mutant strains exhibited a loss of resistance to cell wall-targeting antibiotics. Finally, we show that an E. faecalis epa mutant strain is deficient in intestinal colonization, cannot expand its population upon antibiotic-driven intestinal dysbiosis, and fails to be efficiently transmitted to juvenile mice following birth. This study demonstrates that phage therapy could be used in combination with antibiotics to target enterococci within a dysbiotic microbiota. Enterococci that evade phage therapy by developing resistance may be less fit at colonizing the intestine and sensitized to vancomycin, preventing their overgrowth during antibiotic treatment.
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Genomewide Profiling of the Enterococcus faecalis Transcriptional Response to Teixobactin Reveals CroRS as an Essential Regulator of Antimicrobial Tolerance. mSphere 2019; 4:4/3/e00228-19. [PMID: 31068434 PMCID: PMC6506618 DOI: 10.1128/msphere.00228-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Teixobactin is a new antimicrobial with no known mechanisms of resistance. Understanding how resistance could develop will be crucial to the success and longevity of teixobactin as a new potent antimicrobial. Antimicrobial tolerance has been shown to facilitate the development of resistance, and we show that E. faecalis is intrinsically tolerant to teixobactin at high concentrations. We subsequently chose E. faecalis as a model to elucidate the molecular mechanism underpinning teixobactin tolerance and how this may contribute to the development of teixobactin resistance. Teixobactin is a new antimicrobial of significant interest. It is active against a number of multidrug-resistant pathogens, including Staphylococcus aureus and Enterococcus faecalis, with no reported mechanisms of teixobactin resistance. However, historically, mechanisms of resistance always exist and arise upon introduction of a new antimicrobial into a clinical setting. Therefore, for teixobactin to remain effective long term, we need to understand how mechanisms of resistance could develop. Here we demonstrate that E. faecalis shows a remarkable intrinsic tolerance to high concentrations of teixobactin. This is of critical importance, as antimicrobial tolerance has been shown to precede the development of antimicrobial resistance. To identify potential pathways responsible for this tolerance, we determined the genomewide expression profile of E. faecalis strain JH2-2 in response to teixobactin using RNA sequencing. A total of 573 genes were differentially expressed (2.0-fold log2 change in expression) in response to teixobactin, with genes involved in cell wall biogenesis and division and transport/binding being among those that were the most upregulated. Comparative analyses of E. faecalis cell wall-targeting antimicrobial transcriptomes identified CroRS, LiaRS, and YclRK to be important two-component regulators of antimicrobial-mediated stress. Further investigation of CroRS demonstrated that deletion of croRS abolished tolerance to teixobactin and to other cell wall-targeting antimicrobials. This highlights the crucial role of CroRS in controlling the molecular response to teixobactin. IMPORTANCE Teixobactin is a new antimicrobial with no known mechanisms of resistance. Understanding how resistance could develop will be crucial to the success and longevity of teixobactin as a new potent antimicrobial. Antimicrobial tolerance has been shown to facilitate the development of resistance, and we show that E. faecalis is intrinsically tolerant to teixobactin at high concentrations. We subsequently chose E. faecalis as a model to elucidate the molecular mechanism underpinning teixobactin tolerance and how this may contribute to the development of teixobactin resistance.
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Smith RE, Salamaga B, Szkuta P, Hajdamowicz N, Prajsnar TK, Bulmer GS, Fontaine T, Kołodziejczyk J, Herry JM, Hounslow AM, Williamson MP, Serror P, Mesnage S. Decoration of the enterococcal polysaccharide antigen EPA is essential for virulence, cell surface charge and interaction with effectors of the innate immune system. PLoS Pathog 2019; 15:e1007730. [PMID: 31048927 PMCID: PMC6497286 DOI: 10.1371/journal.ppat.1007730] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/26/2019] [Indexed: 12/13/2022] Open
Abstract
Enterococcus faecalis is an opportunistic pathogen with an intrinsically high resistance to lysozyme, a key effector of the innate immune system. This high level of resistance requires a complex network of transcriptional regulators and several genes (oatA, pgdA, dltA and sigV) acting synergistically to inhibit both the enzymatic and cationic antimicrobial peptide activities of lysozyme. We sought to identify novel genes modulating E. faecalis resistance to lysozyme. Random transposon mutagenesis carried out in the quadruple oatA/pgdA/dltA/sigV mutant led to the identification of several independent insertions clustered on the chromosome. These mutations were located in a locus referred to as the enterococcal polysaccharide antigen (EPA) variable region located downstream of the highly conserved epaA-epaR genes proposed to encode a core synthetic machinery. The epa variable region was previously proposed to be responsible for EPA decorations, but the role of this locus remains largely unknown. Here, we show that EPA decoration contributes to resistance towards charged antimicrobials and underpins virulence in the zebrafish model of infection by conferring resistance to phagocytosis. Collectively, our results indicate that the production of the EPA rhamnopolysaccharide backbone is not sufficient to promote E. faecalis infections and reveal an essential role of the modification of this surface polymer for enterococcal pathogenesis. Enterococcus faecalis is a commensal bacterium colonizing the gastro-intestinal tract of humans. This organism can cause life-threatening opportunistic infections and represents a reservoir for the transmission of antibiotic resistance genes such as resistance to vancomycin. E. faecalis strains responsible for nosocomial infections are also found in healthy individuals and the virulence factors identified so far are not strictly associated with clinical isolates. The molecular basis underpinning E. faecalis infections therefore remains unclear. In this work, we identify several mutations clustered on the chromosome, which play a role in the resistance of E. faecalis to effectors of the innate immune system such as lysozyme and bile salts. We show that the corresponding genes contribute to the decoration of a conserved polysaccharide called the enterococcal polysaccharide antigen and that this decoration is essential for E. faecalis virulence. This mechanism critical for pathogenesis represents an attractive therapeutic target to control enterococcal infections.
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Affiliation(s)
- Robert E. Smith
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Bartłomiej Salamaga
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Piotr Szkuta
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Natalia Hajdamowicz
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Tomasz K. Prajsnar
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Gregory S. Bulmer
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | | | - Justyna Kołodziejczyk
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Jean-Marie Herry
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy en Josas, France
| | - Andrea M. Hounslow
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Mike P. Williamson
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
| | - Pascale Serror
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy en Josas, France
- * E-mail: (PS); (SM)
| | - Stéphane Mesnage
- Krebs Institute, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield, United Kingdom
- * E-mail: (PS); (SM)
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Loss of a Major Enterococcal Polysaccharide Antigen (Epa) by Enterococcus faecalis Is Associated with Increased Resistance to Ceftriaxone and Carbapenems. Antimicrob Agents Chemother 2019; 63:AAC.00481-19. [PMID: 30858216 DOI: 10.1128/aac.00481-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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Ramos Y, Rocha J, Hael AL, van Gestel J, Vlamakis H, Cywes-Bentley C, Cubillos-Ruiz JR, Pier GB, Gilmore MS, Kolter R, Morales DK. PolyGlcNAc-containing exopolymers enable surface penetration by non-motile Enterococcus faecalis. PLoS Pathog 2019; 15:e1007571. [PMID: 30742693 PMCID: PMC6386517 DOI: 10.1371/journal.ppat.1007571] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 02/22/2019] [Accepted: 01/08/2019] [Indexed: 11/20/2022] Open
Abstract
Bacterial pathogens have evolved strategies that enable them to invade tissues and spread within the host. Enterococcus faecalis is a leading cause of local and disseminated multidrug-resistant hospital infections, but the molecular mechanisms used by this non-motile bacterium to penetrate surfaces and translocate through tissues remain largely unexplored. Here we present experimental evidence indicating that E. faecalis generates exopolysaccharides containing β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc) as a mechanism to successfully penetrate semisolid surfaces and translocate through human epithelial cell monolayers. Genetic screening and molecular analyses of mutant strains identified glnA, rpiA and epaX as genes critically required for optimal E. faecalis penetration and translocation. Mechanistically, GlnA and RpiA cooperated to generate uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) that was utilized by EpaX to synthesize polyGlcNAc-containing polymers. Notably, exogenous supplementation with polymeric N-acetylglucosamine (PNAG) restored surface penetration by E. faecalis mutants devoid of EpaX. Our study uncovers an unexpected mechanism whereby the RpiA-GlnA-EpaX metabolic axis enables production of polyGlcNAc-containing polysaccharides that endow E. faecalis with the ability to penetrate surfaces. Hence, targeting carbohydrate metabolism or inhibiting biosynthesis of polyGlcNAc-containing exopolymers may represent a new strategy to more effectively confront enterococcal infections in the clinic. Enterococcus faecalis is a microbial inhabitant of the human gastrointestinal tract that can cause lethal infections. Typically classified as a non-motile bacterium, E. faecalis can readily migrate and translocate across epithelial barriers to invade distant organs. Nevertheless, the molecular pathways driving enterococcal invasive attributes remain poorly understood. In this study, we uncover that E. faecalis produces a polyGlcNAc-containing extracellular glycopolymer to efficiently migrate into semisolid surfaces and translocate through human epithelial cell monolayers. Our work provides evidence that non-motile bacterial pathogens can exploit endogenous carbohydrate metabolic pathways to penetrate surfaces. Thus, targeting glycopolymer biosynthetic programs might be useful to control infections by Gram-positive cocci in the clinic.
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Affiliation(s)
- Yusibeska Ramos
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
| | - Jorge Rocha
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Ana L. Hael
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Hera Vlamakis
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Colette Cywes-Bentley
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Juan R. Cubillos-Ruiz
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
| | - Gerald B. Pier
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michael S. Gilmore
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
- Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| | - Roberto Kolter
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Diana K. Morales
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
- * E-mail:
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Wandro S, Oliver A, Gallagher T, Weihe C, England W, Martiny JBH, Whiteson K. Predictable Molecular Adaptation of Coevolving Enterococcus faecium and Lytic Phage EfV12-phi1. Front Microbiol 2019; 9:3192. [PMID: 30766528 PMCID: PMC6365445 DOI: 10.3389/fmicb.2018.03192] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 12/10/2018] [Indexed: 01/21/2023] Open
Abstract
Bacteriophages are highly abundant in human microbiota where they coevolve with resident bacteria. Phage predation can drive the evolution of bacterial resistance, which can then drive reciprocal evolution in the phage to overcome that resistance. Such coevolutionary dynamics have not been extensively studied in human gut bacteria, and are of particular interest for both understanding and eventually manipulating the human gut microbiome. We performed experimental evolution of an Enterococcus faecium isolate from healthy human stool in the absence and presence of a single infecting Myoviridae bacteriophage, EfV12-phi1. Four replicates of E. faecium and phage were grown with twice daily serial transfers for 8 days. Genome sequencing revealed that E. faecium evolved resistance to phage through mutations in the yqwD2 gene involved in exopolysaccharide biogenesis and export, and the rpoC gene which encodes the RNA polymerase β’ subunit. In response to bacterial resistance, phage EfV12-phi1 evolved varying numbers of 1.8 kb tandem duplications within a putative tail fiber gene. Host range assays indicated that coevolution of this phage-host pair resulted in arms race dynamics in which bacterial resistance and phage infectivity increased over time. Tracking mutations from population sequencing of experimental coevolution can quickly illuminate phage entry points along with resistance strategies in both phage and host – critical information for using phage to manipulate microbial communities.
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Affiliation(s)
- Stephen Wandro
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
| | - Andrew Oliver
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
| | - Tara Gallagher
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
| | - Claudia Weihe
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Whitney England
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States.,Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, United States
| | - Jennifer B H Martiny
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
| | - Katrine Whiteson
- Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States
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Enterococcus faecalis Countermeasures Defeat a Virulent Picovirinae Bacteriophage. Viruses 2019; 11:v11010048. [PMID: 30634666 PMCID: PMC6356687 DOI: 10.3390/v11010048] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 12/29/2018] [Accepted: 12/31/2018] [Indexed: 12/23/2022] Open
Abstract
Enterococcus faecalis is an opportunistic pathogen that has emerged as a major cause of nosocomial infections worldwide. Many clinical strains are indeed resistant to last resort antibiotics and there is consequently a reawakening of interest in exploiting virulent phages to combat them. However, little is still known about phage receptors and phage resistance mechanisms in enterococci. We made use of a prophageless derivative of the well-known clinical strain E. faecalis V583 to isolate a virulent phage belonging to the Picovirinae subfamily and to the P68 genus that we named Idefix. Interestingly, most isolates of E. faecalis tested—including V583—were resistant to this phage and we investigated more deeply into phage resistance mechanisms. We found that E. faecalis V583 prophage 6 was particularly efficient in resisting Idefix infection thanks to a new abortive infection (Abi) mechanism, which we designated Abiα. It corresponded to the Pfam domain family with unknown function DUF4393 and conferred a typical Abi phenotype by causing a premature lysis of infected E. faecalis. The abiα gene is widespread among prophages of enterococci and other Gram-positive bacteria. Furthermore, we identified two genes involved in the synthesis of the side chains of the surface rhamnopolysaccharide that are important for Idefix adsorption. Interestingly, mutants in these genes arose at a frequency of ~10−4 resistant mutants per generation, conferring a supplemental bacterial line of defense against Idefix.
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Banla LI, Salzman NH, Kristich CJ. Colonization of the mammalian intestinal tract by enterococci. Curr Opin Microbiol 2018; 47:26-31. [PMID: 30439685 DOI: 10.1016/j.mib.2018.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/08/2018] [Accepted: 10/16/2018] [Indexed: 02/08/2023]
Abstract
Enterococci are colonizers of the mammalian gastrointestinal tract (GIT) and normally live in healthy association with their human host. However, enterococci are also major causes of healthcare-acquired infections, prompting the US Centers for Disease Control and Prevention to declare vancomycin-resistant enterococci (VRE) a serious threat to public health. Because of both intrinsic and acquired antibiotic resistance, enterococci proliferate in the GIT during antibiotic therapy, leading to dissemination and disease. The recognition that colonization of the GIT is a pre-requisite for enterococcal infections has prompted research to study mechanisms used by enterococci to colonize this niche. This review discusses major findings of recent research to understand GIT colonization by enterococci using diverse experimental models, each of which exhibits unique strengths. This work has revealed enterococcal transcriptional reprogramming in the GIT, contributions of specific enterococcal genes encoded by the core genome to GIT colonization, the impact of genome plasticity, and roles for intra-species and inter-species interactions in modulation of GIT colonization.
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Affiliation(s)
- Leou Ismael Banla
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Nita H Salzman
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States.
| | - Christopher J Kristich
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, United States.
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Loss-of-Function Mutations in epaR Confer Resistance to ϕNPV1 Infection in Enterococcus faecalis OG1RF. Antimicrob Agents Chemother 2018; 62:AAC.00758-18. [PMID: 30104266 PMCID: PMC6153818 DOI: 10.1128/aac.00758-18] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/01/2018] [Indexed: 02/06/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive opportunistic pathogen that inhabits the human gastrointestinal tract. Because of the high frequency of antibiotic resistance among Enterococcus clinical isolates, interest in using phage to treat enterococcal infections and to decolonize high-risk patients for antibiotic-resistant Enterococcus is rising. Bacteria can evolve phage resistance, but there is little published information on these mechanisms in E. faecalis In this report, we identified genetic determinants of E. faecalis resistance to phage NPV1 (ϕNPV1). We found that loss-of-function mutations in epaR confer ϕNPV1 resistance by blocking phage adsorption. We attribute the inability of the phage to adsorb to the modification or loss of an extracellular polymer in strains with inactivated epaR Phage-resistant epaR mutants exhibited increased daptomycin and osmotic stress susceptibilities. Our results demonstrate that in vitro spontaneous resistance to ϕNPV1 comes at a cost in E. faecalis OG1RF.
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Jung A, Chen LR, Suyemoto MM, Barnes HJ, Borst LB. A Review ofEnterococcus cecorumInfection in Poultry. Avian Dis 2018; 62:261-271. [DOI: 10.1637/11825-030618-review.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Arne Jung
- Clinic for Poultry, University of Veterinary Medicine Hannover, Buenteweg 17, D-30559 Hannover, Germany,
| | - Laura R. Chen
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607
| | - M. Mitsu Suyemoto
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607
| | - H. John Barnes
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607
| | - Luke B. Borst
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607
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Comparative Genomics and Description of Putative Virulence Factors of Melissococcus plutonius, the Causative Agent of European Foulbrood Disease in Honey Bees. Genes (Basel) 2018; 9:genes9080419. [PMID: 30127293 PMCID: PMC6116112 DOI: 10.3390/genes9080419] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/13/2018] [Indexed: 11/17/2022] Open
Abstract
In Europe, approximately 84% of cultivated crop species depend on insect pollinators, mainly bees. Apis mellifera (the Western honey bee) is the most important commercial pollinator worldwide. The Gram-positive bacterium Melissococcus plutonius is the causative agent of European foulbrood (EFB), a global honey bee brood disease. In order to detect putative virulence factors, we sequenced and analyzed the genomes of 14 M. plutonius strains, including two reference isolates. The isolates do not show a high diversity in genome size or number of predicted protein-encoding genes, ranging from 2.021 to 2.101 Mbp and 1589 to 1686, respectively. Comparative genomics detected genes that might play a role in EFB pathogenesis and ultimately in the death of the honey bee larvae. These include bacteriocins, bacteria cell surface- and host cell adhesion-associated proteins, an enterococcal polysaccharide antigen, an epsilon toxin, proteolytic enzymes, and capsule-associated proteins. In vivo expression of three putative virulence factors (endo-alpha-N-acetylgalactosaminidase, enhancin and epsilon toxin) was verified using naturally infected larvae. With our strain collection, we show for the first time that genomic differences exist between non-virulent and virulent typical strains, as well as a highly virulent atypical strain, that may contribute to the virulence of M. plutonius. Finally, we also detected a high number of conserved pseudogenes (75 to 156) per genome, which indicates genomic reduction during evolutionary host adaptation.
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Hullahalli K, Rodrigues M, Nguyen UT, Palmer K. An Attenuated CRISPR-Cas System in Enterococcus faecalis Permits DNA Acquisition. mBio 2018; 9:e00414-18. [PMID: 29717009 PMCID: PMC5930301 DOI: 10.1128/mbio.00414-18] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 03/28/2018] [Indexed: 12/13/2022] Open
Abstract
Antibiotic-resistant bacteria are critical public health concerns. Among the prime causative factors for the spread of antibiotic resistance is horizontal gene transfer (HGT). A useful model organism for investigating the relationship between HGT and antibiotic resistance is the opportunistic pathogen Enterococcus faecalis, since the species possesses highly conjugative plasmids that readily disseminate antibiotic resistance genes and virulence factors in nature. Unlike many commensal E. faecalis strains, the genomes of multidrug-resistant (MDR) E. faecalis clinical isolates are enriched for mobile genetic elements (MGEs) and lack clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein (Cas) genome defense systems. CRISPR-Cas systems cleave foreign DNA in a programmable, sequence-specific manner and are disadvantageous for MGE-derived genome expansion. An unexplored facet of CRISPR biology in E. faecalis is that MGEs that are targeted by native CRISPR-Cas systems can be maintained transiently. Here, we investigate the basis for this "CRISPR tolerance." We observe that E. faecalis can maintain self-targeting constructs that direct Cas9 to cleave the chromosome, but at a fitness cost. Interestingly, DNA repair genes were not upregulated during self-targeting, but integrated prophages were strongly induced. We determined that low cas9 expression contributes to this transient nonlethality and used this knowledge to develop a robust CRISPR-assisted genome-editing scheme. Our results suggest that E. faecalis has maximized the potential for DNA acquisition by attenuating its CRISPR machinery, thereby facilitating the acquisition of potentially beneficial MGEs that may otherwise be restricted by genome defense.IMPORTANCE CRISPR-Cas has provided a powerful toolkit to manipulate bacteria, resulting in improved genetic manipulations and novel antimicrobials. These powerful applications rely on the premise that CRISPR-Cas chromosome targeting, which leads to double-stranded DNA breaks, is lethal. In this study, we show that chromosomal CRISPR targeting in Enterococcus faecalis is transiently nonlethal. We uncover novel phenotypes associated with this "CRISPR tolerance" and, after determining its genetic basis, develop a genome-editing platform in E. faecalis with negligible off-target effects. Our findings reveal a novel strategy exploited by a bacterial pathogen to cope with CRISPR-induced conflicts to more readily accept DNA, and our robust CRISPR editing platform will help simplify genetic modifications in this organism.
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Affiliation(s)
- Karthik Hullahalli
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Marinelle Rodrigues
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Uyen Thy Nguyen
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
| | - Kelli Palmer
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA
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Goh HMS, Yong MHA, Chong KKL, Kline KA. Model systems for the study of Enterococcal colonization and infection. Virulence 2017; 8:1525-1562. [PMID: 28102784 PMCID: PMC5810481 DOI: 10.1080/21505594.2017.1279766] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/30/2016] [Accepted: 01/04/2017] [Indexed: 02/07/2023] Open
Abstract
Enterococcus faecalis and Enterococcus faecium are common inhabitants of the human gastrointestinal tract, as well as frequent opportunistic pathogens. Enterococci cause a range of infections including, most frequently, infections of the urinary tract, catheterized urinary tract, bloodstream, wounds and surgical sites, and heart valves in endocarditis. Enterococcal infections are often biofilm-associated, polymicrobial in nature, and resistant to antibiotics of last resort. Understanding Enterococcal mechanisms of colonization and pathogenesis are important for identifying new ways to manage and intervene with these infections. We review vertebrate and invertebrate model systems applied to study the most common E. faecalis and E. faecium infections, with emphasis on recent findings examining Enterococcal-host interactions using these models. We discuss strengths and shortcomings of each model, propose future animal models not yet applied to study mono- and polymicrobial infections involving E. faecalis and E. faecium, and comment on the significance of anti-virulence strategies derived from a fundamental understanding of host-pathogen interactions in model systems.
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Affiliation(s)
- H. M. Sharon Goh
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - M. H. Adeline Yong
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Kelvin Kian Long Chong
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
- Singapore Centre for Environmental Life Sciences Engineering, Interdisciplinary Graduate School, Nanyang Technological University, Singapore
| | - Kimberly A. Kline
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
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