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Daca A, Piechowicz L, Wiśniewska K, Bryl E, Witkowski JM, Jarzembowski T. Both biofilm cytotoxicity and monocytes' adhesion may be used as estimators of enterococcal virulence. Lett Appl Microbiol 2024; 77:ovae047. [PMID: 38755018 DOI: 10.1093/lambio/ovae047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 04/13/2024] [Accepted: 05/15/2024] [Indexed: 05/18/2024]
Abstract
Our study aimed to identify markers of enterococci's virulence potential by evaluating the properties of strains of different sites of isolation. Enterococcal strains were isolated as commensals from faeces and as invasive strains from the urine and blood of patients from the University Clinical Centre, Gdańsk, Poland. Changes in monocytes' susceptibility to the cytotoxic activity of isolates of different origins and their adherence to biofilm were evaluated using a flow cytometer. The bacterial protein profile was estimated by matrix assisted laser desorption ionization-time of flight mass spectrometer. The cytotoxicity of biofilm and monocytes' adherence to it were the most accurate factors in predicting the prevalence of the strain in the specific niche. Additionally, a bacterial protein with mass-to-charge ratio (m/z) 5000 was found to be responsible for the increased bacterial cytotoxicity, while monocytes' decreased adherence to biofilm was linked with the presence of proteins either with m/z 3330 or 2435. The results illustrate that monocytes' reaction when exposed to the bacterial biofilm can be used as an estimator of pathogens' virulence potential. The observed differences in monocytes' response are explainable by the bacterial proteins' profile. Additionally, the results indicate that the features of both bacteria and monocytes impact the outcome of the infection.
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Affiliation(s)
- Agnieszka Daca
- Department of Physiopathology, Medical University of Gdansk, Dębinki 7, 80-211 Gdansk, Poland
- Division of Pathology and Experimental Rheumatology, Medical University of Gdańsk, Dębinki 7, 80-211 Gdańsk, Poland
| | - Lidia Piechowicz
- Department of Microbiology, Medical University of Gdansk, Dębowa 25, 80-204 Gdansk, Poland
| | - Katarzyna Wiśniewska
- Department of Microbiology, Medical University of Gdansk, Dębowa 25, 80-204 Gdansk, Poland
| | - Ewa Bryl
- Department of Physiopathology, Medical University of Gdansk, Dębinki 7, 80-211 Gdansk, Poland
- Division of Pathology and Experimental Rheumatology, Medical University of Gdańsk, Dębinki 7, 80-211 Gdańsk, Poland
| | - Jacek M Witkowski
- Department of Physiopathology, Medical University of Gdansk, Dębinki 7, 80-211 Gdansk, Poland
- Department of Anatomy, Division of Embryology, Medical University of Gdańsk, Dębinki 1, 80-211 Gdańsk, Poland
| | - Tomasz Jarzembowski
- Department of Microbiology, Medical University of Gdansk, Dębowa 25, 80-204 Gdansk, Poland
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Jackson JJ, Heyer S, Bell G. Sortase-encoding genes, srtA and srtC, mediate Enterococcus faecalis OG1RF persistence in the Helicoverpa zea gastrointestinal tract. Front Microbiol 2024; 15:1322303. [PMID: 38562482 PMCID: PMC10982312 DOI: 10.3389/fmicb.2024.1322303] [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: 10/16/2023] [Accepted: 02/19/2024] [Indexed: 04/04/2024] Open
Abstract
Enterococcus faecalis is a commensal and opportunistic pathogen in the gastrointestinal (GI) tract of mammals and insects. To investigate mechanisms of bacterial persistence in the gastrointestinal tract (GIT), we developed a non-destructive sampling model using Helicoverpa zea, a destructive agricultural pest, as host to study the role of bacterial sortase enzymes in mitigating persistence in the gastrointestinal tract. E. faecalis OG1RF ΔsrtA and E. faecalis OG1RF ΔsrtC, isogenic E. faecalis OG1RF sortase mutants grew similarly under planktonic growth conditions relative to a streptomycin-resistant E. faecalis OG1RFS WT in vitro but displayed impaired biofilm formation under, both, physiological and alkaline conditions. In the H. zea GI model, both mutants displayed impaired persistence relative to the WT. This represents one of the initial reports in which a non-destructive insect model has been used to characterize mechanisms of bacterial persistence in the Lepidopteran midgut and, furthermore, sheds light on new molecular mechanisms employed by diverse microorganisms to associate with invertebrate hosts.
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Affiliation(s)
- Jerreme J. Jackson
- Department of Biology, University of Northern Iowa, Cedar Falls, IA, United States
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Sacramento AG, Fuga B, Fontana H, Cardoso B, Esposito F, Vivas R, Malta JAO, Sellera FP, Lincopan N. Successful expansion of hospital-associated clone of vanA-positive vancomycin-resistant Enterococcus faecalis ST9 to an anthropogenically polluted mangrove in Brazil. MARINE POLLUTION BULLETIN 2024; 198:115844. [PMID: 38056291 DOI: 10.1016/j.marpolbul.2023.115844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/21/2023] [Accepted: 11/23/2023] [Indexed: 12/08/2023]
Abstract
Mangrove ecosystems are hotspots of biodiversity, but have been threatened by anthropogenic activities. Vancomycin-resistant enterococci (VRE) are nosocomial bacteria classified as high priority by the World Health Organization (WHO). Herein, we describe the identification and genomic characteristics of a vancomycin-resistant Enterococcus faecalis strain isolated from a highly impacted mangrove ecosystem of the northeastern Brazilian, in 2021. Genomic analysis confirmed the existence of the transposon Tn1546-vanA and clinically relevant antimicrobial resistance genes, such as streptogramins, tetracycline, phenicols, and fluoroquinolones. Virulome analysis identified several genes associated to adherence, immune modulation, biofilm, and exoenzymes production. The UFSEfl strain was assigned to sequence type (ST9), whereas phylogenomic analysis with publicly available genomes from a worldwide confirmed clonal relatedness with a hospital-associated Brazilian clone. Our findings highlight the successful expansion of hospital-associated VRE in a mangrove area and shed light on the need for strengthening genomic surveillance of WHO priority pathogens in these vital ecosystems.
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Affiliation(s)
- Andrey G Sacramento
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
| | - Bruna Fuga
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Department of Clinical Analysis, School of Pharmacy, University of São Paulo, São Paulo, Brazil
| | - Herrison Fontana
- Department of Clinical Analysis, School of Pharmacy, University of São Paulo, São Paulo, Brazil
| | - Brenda Cardoso
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Fernanda Esposito
- Department of Clinical Analysis, School of Pharmacy, University of São Paulo, São Paulo, Brazil
| | - Roberto Vivas
- Microbiology Laboratory, Sergipe Urgent Care Hospital (HUSE), Aracaju, Brazil
| | - Judson A O Malta
- Postgraduate Program in Development and Environment (PRODEMA), Federal University of Sergipe, São Cristóvão, Brazil
| | - Fábio P Sellera
- School of Veterinary Medicine, Metropolitan University of Santos, Santos, Brazil; Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Nilton Lincopan
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Department of Clinical Analysis, School of Pharmacy, University of São Paulo, São Paulo, Brazil
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Choo PY, Wang CY, VanNieuwenhze MS, Kline KA. Spatial and temporal localization of cell wall associated pili in Enterococcus faecalis. Mol Microbiol 2023; 119:1-18. [PMID: 36420961 PMCID: PMC10107303 DOI: 10.1111/mmi.15008] [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: 05/16/2022] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022]
Abstract
Enterococcus faecalis virulence requires cell wall-associated proteins, including the sortase-assembled endocarditis and biofilm associated pilus (Ebp), important for biofilm formation in vitro and in vivo. The current paradigm for sortase-assembled pilus biogenesis in Gram-positive bacteria is that sortases attach substrates to lipid II peptidoglycan (PG) precursors, prior to their incorporation into the growing cell wall. Contrary to prevailing dogma, by following the distribution of Ebp and PG throughout the E. faecalis cell cycle, we found that cell surface Ebp do not co-localize with newly synthesized PG. Instead, surface-exposed Ebp are localized to the older cell hemisphere and excluded from sites of new PG synthesis at the septum. Moreover, Ebp deposition on the younger hemisphere of the E. faecalis diplococcus appear as foci adjacent to the nascent septum. We propose a new model whereby sortase substrate deposition can occur on older PG rather than at sites of new cell wall synthesis. Consistent with this model, we demonstrate that sequestering lipid II to block PG synthesis via ramoplanin, does not impact new Ebp deposition at the cell surface. These data support an alternative paradigm for sortase substrate deposition in E. faecalis, in which Ebp are anchored directly onto uncrosslinked cell wall, independent of new PG synthesis.
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Affiliation(s)
- Pei Yi Choo
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Charles Y Wang
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | | | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland
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Shanmugasundarasamy T, Karaiyagowder Govindarajan D, Kandaswamy K. A review on pilus assembly mechanisms in Gram-positive and Gram-negative bacteria. Cell Surf 2022; 8:100077. [PMID: 35493982 PMCID: PMC9046445 DOI: 10.1016/j.tcsw.2022.100077] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/08/2022] [Accepted: 04/18/2022] [Indexed: 12/17/2022] Open
Abstract
The surface of Gram-positive and Gram-negative bacteria contains long hair-like proteinaceous protrusion known as pili or fimbriae. Historically, pilin proteins were considered to play a major role in the transfer of genetic material during bacterial conjugation. Recent findings however elucidate their importance in virulence, biofilm formation, phage transduction, and motility. Therefore, it is crucial to gain mechanistic insights on the subcellular assembly of pili and the localization patterns of their subunit proteins (major and minor pilins) that aid the macromolecular pilus assembly at the bacterial surface. In this article, we review the current knowledge of pilus assembly mechanisms in a wide range of Gram-positive and Gram-negative bacteria, including subcellular localization patterns of a few pilin subunit proteins and their role in virulence and pathogenesis.
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Li L, Li Y, Yang J, Xie X, Chen H. The immune responses to different Uropathogens call individual interventions for bladder infection. Front Immunol 2022; 13:953354. [PMID: 36081496 PMCID: PMC9445553 DOI: 10.3389/fimmu.2022.953354] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/05/2022] [Indexed: 11/13/2022] Open
Abstract
Urinary tract infection (UTI) caused by uropathogens is the most common infectious disease and significantly affects all aspects of the quality of life of the patients. However, uropathogens are increasingly becoming antibiotic-resistant, which threatens the only effective treatment option available-antibiotic, resulting in higher medical costs, prolonged hospital stays, and increased mortality. Currently, people are turning their attention to the immune responses, hoping to find effective immunotherapeutic interventions which can be alternatives to the overuse of antibiotic drugs. Bladder infections are caused by the main nine uropathogens and the bladder executes different immune responses depending on the type of uropathogens. It is essential to understand the immune responses to diverse uropathogens in bladder infection for guiding the design and development of immunotherapeutic interventions. This review firstly sorts out and comparatively analyzes the immune responses to the main nine uropathogens in bladder infection, and summarizes their similarities and differences. Based on these immune responses, we innovatively propose that different microbial bladder infections should adopt corresponding immunomodulatory interventions, and the same immunomodulatory intervention can also be applied to diverse microbial infections if they share the same effective therapeutic targets.
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Affiliation(s)
- Linlong Li
- The School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
| | - Yangyang Li
- The School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
| | - Jiali Yang
- The School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
| | - Xiang Xie
- The School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
- Public Center of Experimental Technology, Model Animal and Human Disease Research of Luzhou Key Laboratory, Southwest Medical University, Luzhou, China
- *Correspondence: Xiang Xie, ; Huan Chen,
| | - Huan Chen
- The School of Basic Medical Sciences, Southwest Medical University, Luzhou, China
- Nucleic Acid Medicine of Luzhou Key Laboratory, Southwest Medical University, Luzhou, China
- *Correspondence: Xiang Xie, ; Huan Chen,
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Lepold AM, Tesfamichael DH, Hartmann FA, Wiley CA, Wood MW. Comparison of urine fibrinogen and interleukin-6 concentrations between healthy dogs and dogs with risk factors for enterococcal bacteriuria. Am J Vet Res 2021; 82:846-852. [PMID: 34554867 DOI: 10.2460/ajvr.82.10.846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare urine concentrations of fibrinogen (uFIB) and interleukin-6 (uIL-6) between dogs with risk factors for enterococcal bacteriuria and healthy dogs. SAMPLE Banked urine samples with negative aerobic culture results from 8 dogs with urolithiasis, 9 dogs with anatomic abnormalities of the lower portion of the urinary tract (LUT), 10 dogs with LUT neoplasia, and 21 healthy control dogs. PROCEDURES Urine creatinine concentration (uCrea) was determined by an automated biochemical analyzer, and uFIB and uIL-6 were determined by dog-specific ELISAs. The uFIB:uCrea and uIL-6:uCrea ratios were calculated for each sample to normalize intersample differences in urine concentration and were compared among the 4 experimental groups. RESULTS Median uFIB:uCrea ratios for dogs with urolithiasis (0.72; interquartile [25th to 75 percentile] range [IQR], 0.46 to 3.48) and LUT neoplasia (6.16; IQR, 3.89 to 12.75), but not for dogs with LUT anatomic abnormalities (0.48; IQR, 0.27 to 0.69), were significantly greater than that for control dogs (0.17; IQR, 0.07 to 0.39). Median uIL-6: uCrea ratios for dogs with urolithiasis (0.48; IQR, 0.18 to 1.61), LUT anatomic abnormalities (0.25; IQR, 0.17 to 0.33), and LUT neoplasia (0.25; IQR, 0.12 to 1.01) were significantly greater than that for control dogs (0.08; IQR, 0.06 to 0.11). CONCLUSIONS AND CLINICAL RELEVANCE The uFIB and uIL-6 in dogs with risk factors for enterococcal bacteriuria were generally greater than corresponding values in control dogs. Further investigation is necessary to determine the role of fibrinogen in enterococcal colonization of the urinary tract of dogs.
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Suryaletha K, Chandrika SK, Thomas S. Comprehensive genomics depict accessory genes encoding pathogenicity and biofilm determinants in Enterococcus faecalis. Future Microbiol 2021; 16:175-184. [PMID: 33528277 DOI: 10.2217/fmb-2020-0111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aim: Enterococcus faecalis is a leading nosocomial pathogen in biofilm-associated polymicrobial infections. The study aims to understand pathogenicity and biofilm determinants of the pathogen by genome analysis. Methodology: Genome sequencing of a strong biofilm forming clinical isolate Enterococcus faecalis SK460 devoid of Fsr quorum-signaling system, was performed and comparative genomics was carried out among a set of pathogenic biofilm formers and nonpathogenic weak biofilm formers. Results: Analysis revealed a pool of virulence and adhesion related factors associated with pathogenicity. Absence of CRISPR-Cas system facilitated acquisition of pheromone responsive plasmid, pathogenicity island and phages. Comprehensive analysis identified a subset of accessory genes encoding polysaccharide lyase, sugar phosphotransferase system, phage proteins and transcriptional regulators exclusively in pathogenic biofilm formers. Conclusion: The study identified a set of genes specific to pathogenic biofilm formers and these can act as targets which in turn help to develop future treatment endeavors against enterococcal infections.
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Affiliation(s)
- Karthika Suryaletha
- Cholera & Biofilm Research Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695 014, Kerala, India
| | - Sivakumar K Chandrika
- Distributed Information Sub-Centre, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695 014, Kerala, India
| | - Sabu Thomas
- Cholera & Biofilm Research Laboratory, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695 014, Kerala, India
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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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Alhajjar N, Chatterjee A, Spencer BL, Burcham LR, Willett JLE, Dunny GM, Duerkop BA, Doran KS. Genome-Wide Mutagenesis Identifies Factors Involved in Enterococcus faecalis Vaginal Adherence and Persistence. Infect Immun 2020; 88:e00270-20. [PMID: 32778611 PMCID: PMC7504943 DOI: 10.1128/iai.00270-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/26/2020] [Indexed: 02/08/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive commensal bacterium native to the gastrointestinal tract and an opportunistic pathogen of increasing clinical concern. E. faecalis also colonizes the female reproductive tract, and reports suggest vaginal colonization increases following antibiotic treatment or in patients with aerobic vaginitis. Currently, little is known about specific factors that promote E. faecalis vaginal colonization and subsequent infection. We modified an established mouse vaginal colonization model to explore E. faecalis vaginal carriage and demonstrate that both vancomycin-resistant and -sensitive strains colonize the murine vaginal tract. Following vaginal colonization, we observed E. faecalis in vaginal, cervical, and uterine tissue. A mutant lacking endocarditis- and biofilm-associated pili (Ebp) exhibited a decreased ability to associate with human vaginal and cervical cells in vitro but did not contribute to colonization in vivo Thus, we screened a low-complexity transposon (Tn) mutant library to identify novel genes important for E. faecalis colonization and persistence in the vaginal tract. This screen revealed 383 mutants that were underrepresented during vaginal colonization at 1, 5, and 8 days postinoculation compared to growth in culture medium. We confirmed that mutants deficient in ethanolamine catabolism or in the type VII secretion system were attenuated in persisting during vaginal colonization. These results reveal the complex nature of vaginal colonization and suggest that multiple factors contribute to E. faecalis persistence in the reproductive tract.
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Affiliation(s)
- Norhan Alhajjar
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Anushila Chatterjee
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Brady L Spencer
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Lindsey R Burcham
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Julia L E Willett
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Gary M Dunny
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, Minnesota, USA
| | - Breck A Duerkop
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kelly S Doran
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado, USA
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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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12
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Bin-Asif H, Abid Ali S. The Genus Enterococcus and Its Associated Virulent Factors. Microorganisms 2020. [DOI: 10.5772/intechopen.89083] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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13
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Tan CAZ, Antypas H, Kline KA. Overcoming the challenge of establishing biofilms in vivo: a roadmap for Enterococci. Curr Opin Microbiol 2020; 53:9-18. [PMID: 32062025 DOI: 10.1016/j.mib.2020.01.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/10/2020] [Accepted: 01/15/2020] [Indexed: 12/28/2022]
Abstract
Enterococcus faecalis forms single and mixed-species biofilms on both tissue and medical devices in the host, often under exposure to fluid flow, giving rise to infections that are recalcitrant to treatment. The factors that drive enterococcal biofilm formation in the host, however, remain unclear. Recent reports in other pathogens show how surface sensing by bacteria can trigger the transition from planktonic to sessile lifestyle. Fluid flow can enhance initial adhesion, but also influence quorum sensing. Biofilm-specific factors, as well as biofilm size and extracellular polymeric substances, can compromise opsonization and phagocytosis. Bacterial interspecies synergy can create favorable conditions in the host for biofilm formation. Through these concepts, we define the knowledge gaps in understanding host-associated E. faecalis biofilm formation and propose a roadmap for future investigations.
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Affiliation(s)
- Casandra Ai Zhu Tan
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Haris Antypas
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, 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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(p)ppGpp and CodY Promote Enterococcus faecalis Virulence in a Murine Model of Catheter-Associated Urinary Tract Infection. mSphere 2019; 4:4/4/e00392-19. [PMID: 31341072 PMCID: PMC6656871 DOI: 10.1128/msphere.00392-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Catheter-associated urinary tract infections (CAUTIs) are one of the most frequent types of infection found in the hospital setting that can develop into serious and potentially fatal bloodstream infections. One of the infectious agents that frequently causes complicated CAUTI is the bacterium Enterococcus faecalis, a leading cause of hospital-acquired infections that are often difficult to treat due to the exceptional multidrug resistance of some isolates. Understanding the mechanisms by which E. faecalis causes CAUTI will aid in the discovery of new druggable targets to treat these infections. In this study, we report the importance of two nutrient-sensing bacterial regulators, named (p)ppGpp and CodY, for the ability of E. faecalis to infect the catheterized bladder of mice. In Firmicutes, the nutrient-sensing regulators (p)ppGpp, the effector molecule of the stringent response, and CodY work in tandem to maintain bacterial fitness during infection. Here, we tested (p)ppGpp and codY mutant strains of Enterococcus faecalis in a catheter-associated urinary tract infection (CAUTI) mouse model and used global transcriptional analysis to investigate the relationship of (p)ppGpp and CodY. The absence of (p)ppGpp or single inactivation of codY led to lower bacterial loads in catheterized bladders and diminished biofilm formation on fibrinogen-coated surfaces under in vitro and in vivo conditions. Single inactivation of the bifunctional (p)ppGpp synthetase/hydrolase rel did not affect virulence, supporting previous evidence that the association of (p)ppGpp with enterococcal virulence is not dependent on the activation of the stringent response. Inactivation of codY in the (p)ppGpp0 strain restored E. faecalis virulence in the CAUTI model as well as the ability to form biofilms in vitro. Transcriptome analysis revealed that inactivation of codY restores, for the most part, the dysregulated metabolism of (p)ppGpp0 cells. While a clear linkage between (p)ppGpp and CodY with expression of virulence factors could not be established, targeted transcriptional analysis indicates that a possible association between (p)ppGpp and c-di-AMP signaling pathways in response to the conditions found in the bladder may play a role in enterococcal CAUTI. Collectively, data from this study identify the (p)ppGpp-CodY network as an important contributor to enterococcal virulence in catheterized mouse bladder and support that basal (p)ppGpp pools and CodY promote virulence through maintenance of a balanced metabolism under adverse conditions. IMPORTANCE Catheter-associated urinary tract infections (CAUTIs) are one of the most frequent types of infection found in the hospital setting that can develop into serious and potentially fatal bloodstream infections. One of the infectious agents that frequently causes complicated CAUTI is the bacterium Enterococcus faecalis, a leading cause of hospital-acquired infections that are often difficult to treat due to the exceptional multidrug resistance of some isolates. Understanding the mechanisms by which E. faecalis causes CAUTI will aid in the discovery of new druggable targets to treat these infections. In this study, we report the importance of two nutrient-sensing bacterial regulators, named (p)ppGpp and CodY, for the ability of E. faecalis to infect the catheterized bladder of mice.
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15
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Fiore E, Van Tyne D, Gilmore MS. Pathogenicity of Enterococci. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0053-2018. [PMID: 31298205 PMCID: PMC6629438 DOI: 10.1128/microbiolspec.gpp3-0053-2018] [Citation(s) in RCA: 204] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Indexed: 12/19/2022] Open
Abstract
Enterococci are unusually well adapted for survival and persistence in a variety of adverse environments, including on inanimate surfaces in the hospital environment and at sites of infection. This intrinsic ruggedness undoubtedly played a role in providing opportunities for enterococci to interact with other overtly drug-resistant microbes and acquire additional resistances on mobile elements. The rapid rise of antimicrobial resistance among hospital-adapted enterococci has rendered hospital-acquired infections a leading therapeutic challenge. With about a quarter of a genome of additional DNA conveyed by mobile elements, there are undoubtedly many more properties that have been acquired that help enterococci persist and spread in the hospital setting and cause diseases that have yet to be defined. Much remains to be learned about these ancient and rugged microbes, particularly in the area of pathogenic mechanisms involved with human diseases.
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Affiliation(s)
- Elizabeth Fiore
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA 02114
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
| | - Daria Van Tyne
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA 02114
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
| | - Michael S Gilmore
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA 02114
- Department of Microbiology, Harvard Medical School, Boston, MA 02115
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16
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Sortase-Dependent Proteins Promote Gastrointestinal Colonization by Enterococci. Infect Immun 2019; 87:IAI.00853-18. [PMID: 30804098 DOI: 10.1128/iai.00853-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/18/2019] [Indexed: 12/19/2022] Open
Abstract
The human gastrointestinal tract (GIT) is inhabited by a dense microbial community of symbionts. Enterococci are among the earliest members of this community and remain core members of the GIT microbiota throughout life. Enterococci have also recently emerged as opportunistic pathogens and major causes of nosocomial infections. Although recognized as a prerequisite for infection, colonization of the GIT by enterococci remains poorly understood. One way that bacteria adapt to dynamic ecosystems like the GIT is through the use of their surface proteins to sense and interact with components of their immediate environment. In Gram-positive bacteria, a subset of surface proteins relies on an enzyme called sortase for covalent attachment to the cell wall. Here, we show that the housekeeping sortase A (SrtA) enzyme promotes intestinal colonization by enterococci. Furthermore, we show that the enzymatic activity of SrtA is key to the ability of Enterococcus faecalis to bind mucin (a major component of the GIT mucus). We also report the GIT colonization phenotypes of E. faecalis mutants lacking selected sortase-dependent proteins (SDPs). Further examination of the mucin binding ability of these mutants suggests that adhesion to mucin contributes to intestinal colonization by E. faecalis.
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17
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Saffari F, Sobhanipoor MH, Shahravan A, Ahmadrajabi R. Virulence Genes, Antibiotic Resistance and Capsule Locus Polymorphisms in Enterococcus faecalis isolated from Canals of Root-Filled Teeth with Periapical Lesions. Infect Chemother 2019; 50:340-345. [PMID: 30600657 PMCID: PMC6312899 DOI: 10.3947/ic.2018.50.4.340] [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] [Received: 05/21/2018] [Accepted: 10/31/2018] [Indexed: 11/24/2022] Open
Abstract
Frequent isolation of Enterococcus faecalis from root canal treated teeth with apical periodontitis, has proposed the role of this organism in endodontic treatment failures. Different factors have been suggested in the pathogenicity of this organism. In this study, 22 E. faecalis isolates from canals of root-filled teeth were identified, and phenotypic and genotypic characteristics were investigated. No resistance to vancomycin and gentamicin was noted, and most isolates (91%) were susceptible to ampicillin. Biofilm formation was detected in 73% of the isolates and may be considered as the most important virulence factor involved in the pathogenesis of these isolates.
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Affiliation(s)
- Fereshteh Saffari
- Department of Microbiology and Virology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
| | | | - Arash Shahravan
- Endodontology Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Roya Ahmadrajabi
- Faculty of Medicine, Microbiology Section, Bam University of Medical Sciences, Bam, Iran.
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18
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Flores-Mireles A, Hreha TN, Hunstad DA. Pathophysiology, Treatment, and Prevention of Catheter-Associated Urinary Tract Infection. Top Spinal Cord Inj Rehabil 2019; 25:228-240. [PMID: 31548790 PMCID: PMC6743745 DOI: 10.1310/sci2503-228] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Urinary tract infections (UTIs) are among the most common microbial infections in humans and represent a substantial burden on the health care system. UTIs can be uncomplicated, as when affecting healthy individuals, or complicated, when affecting individuals with compromised urodynamics and/or host defenses, such as those with a urinary catheter. There are clear differences between uncomplicated UTI and catheter-associated UTI (CAUTI) in clinical manifestations, causative organisms, and pathophysiology. Therefore, uncomplicated UTI and CAUTI cannot be approached similarly, or the risk of complications and treatment failure may increase. It is imperative to understand the key aspects of each condition to develop successful treatment options and improve patient outcomes. Here, we will review the epidemiology, pathogen prevalence, differential mechanisms used by uropathogens, and treatment and prevention of uncomplicated UTI and CAUTI.
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Affiliation(s)
| | - Teri N. Hreha
- Washington University School of Medicine, Saint Louis, Missouri
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19
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Colomer-Winter C, Lemos JA, Flores-Mireles AL. Biofilm Assays on Fibrinogen-coated Silicone Catheters and 96-well Polystyrene Plates. Bio Protoc 2019; 9:e3196. [PMID: 31106237 DOI: 10.21769/bioprotoc.3196] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Biofilm formation is a well-known bacterial strategy that protects cells from hostile environments. During infection, bacteria found in a biofilm community are less sensitive to antibiotics and to the immune response, often allowing them to colonize and persist in the host niche. Not surprisingly, biofilm formation on medical devices, such as urinary catheters, is a major problem in hospital settings. To be able to eliminate such biofilms, it is important to understand the key bacterial factors that contribute to their formation. A common practice in the lab setting is to study biofilms grown in laboratory media. However, these media do not fully reflect the host environment conditions, potentially masking relevant biological determinants. This is the case during urinary catheterization, where a key element for Enterococcus faecalis and Staphylococcus aureus colonization and biofilm formation is the release of fibrinogen (Fg) into the bladder and its deposition on the urinary catheter. To recapitulate bladder conditions during catheter-associated urinary tract infection (CAUTI), we have developed a fibrinogen-coated catheter and 96-well plate biofilm assay in urine. Notably, enterococcal biofilm factors identified in these in vitro assays proved to be important for biofilm formation in vivo in a mouse model of CAUTI. Thus, the method described herein can be used to uncover biofilm-promoting factors that are uniquely relevant in the host environment, and that can be exploited to develop new antibacterial therapies.
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Affiliation(s)
- Cristina Colomer-Winter
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - José A Lemos
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Ana L Flores-Mireles
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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20
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Planktonic Interference and Biofilm Alliance between Aggregation Substance and Endocarditis- and Biofilm-Associated Pili in Enterococcus faecalis. J Bacteriol 2018; 200:JB.00361-18. [PMID: 30249706 PMCID: PMC6256026 DOI: 10.1128/jb.00361-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 09/05/2018] [Indexed: 12/13/2022] Open
Abstract
Most bacteria express multiple adhesins that contribute to surface attachment and colonization. However, the network and relationships between the various adhesins of a single bacterial species are less well understood. Here, we examined two well-characterized adhesins in Enterococcus faecalis, aggregation substance and endocarditis- and biofilm-associated pili, and found that they exhibit distinct functional contributions depending on the growth stage of the bacterial community. Pili interfere with aggregation substance-mediated clumping and plasmid transfer under planktonic conditions, whereas the two adhesins structurally complement one another during biofilm development. This study advances our understanding of how E. faecalis, a ubiquitous member of the human gut microbiome and an opportunistic pathogen, uses multiple surface structures to evolve and thrive. Like many bacteria, Enterococcus faecalis encodes a number of adhesins involved in colonization or infection of different niches. Two well-studied E. faecalis adhesins, aggregation substance (AS) and endocarditis- and biofilm-associated pili (Ebp), both contribute to biofilm formation on abiotic surfaces and in endocarditis, suggesting that they may be expressed at the same time. Because different regulatory pathways have been reported for AS and Ebp, here, we examined if they are coexpressed on the same cells and what is the functional impact of coexpression on individual cells and within a population. We found that while Ebp are only expressed on a subset of cells, when Ebp and AS are expressed on the same cells, pili interfere with AS-mediated clumping and impede AS-mediated conjugative plasmid transfer during planktonic growth. However, when the population density increases, horizontal gene transfer rates normalize and are no longer affected by pilus expression. Instead, at higher cell densities during biofilm formation, Ebp and AS differentially contribute to biofilm development and structure, synergizing to promote maximal biofilm formation. IMPORTANCE Most bacteria express multiple adhesins that contribute to surface attachment and colonization. However, the network and relationships between the various adhesins of a single bacterial species are less well understood. Here, we examined two well-characterized adhesins in Enterococcus faecalis, aggregation substance and endocarditis- and biofilm-associated pili, and found that they exhibit distinct functional contributions depending on the growth stage of the bacterial community. Pili interfere with aggregation substance-mediated clumping and plasmid transfer under planktonic conditions, whereas the two adhesins structurally complement one another during biofilm development. This study advances our understanding of how E. faecalis, a ubiquitous member of the human gut microbiome and an opportunistic pathogen, uses multiple surface structures to evolve and thrive.
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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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22
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Ch’ng JH, Chong KKL, Lam LN, Wong JJ, Kline KA. Biofilm-associated infection by enterococci. Nat Rev Microbiol 2018; 17:82-94. [DOI: 10.1038/s41579-018-0107-z] [Citation(s) in RCA: 163] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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23
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Colomer-Winter C, Gaca AO, Chuang-Smith ON, Lemos JA, Frank KL. Basal levels of (p)ppGpp differentially affect the pathogenesis of infective endocarditis in Enterococcus faecalis. MICROBIOLOGY (READING, ENGLAND) 2018; 164:1254-1265. [PMID: 30091695 PMCID: PMC6600344 DOI: 10.1099/mic.0.000703] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 07/18/2018] [Indexed: 12/19/2022]
Abstract
The alarmone (p)ppGpp mediates the stringent response and has a recognized role in bacterial virulence. We previously reported a stringent response-like state in Enterococcus faecalis isolated from a rabbit foreign body abscess model and showed that E. faecalis mutants with varying levels of cellular (p)ppGpp [Δrel, ΔrelQ and the (p)ppGpp0 ΔrelΔrelQ] had differential abilities to persist within abscesses. In this study, we investigated whether (p)ppGpp contributes to the pathogenesis of E. faecalis infective endocarditis (IE), a biofilm infection of the heart valves. While the stringent response was not activated in heart valve-associated E. faecalis, deletion of the gene encoding the bifunctional (p)ppGpp synthetase/hydrolase Rel significantly impaired valve colonization. These results indicate that the presence of (p)ppGpp is dispensable for E. faecalis to cause IE, whereas the ability to regulate (p)ppGpp levels is critical for valve colonization. Next, we characterized how basal (p)ppGpp levels affect processes associated with IE pathogenesis. Despite being defective in binding to BSA-coated polystyrene surfaces, the Δrel strain bound to collagen- and fibronectin-coated surfaces and ex vivo porcine heart valves as well as the parent and ΔrelΔrelQ strains, ruling out the possibility that the impaired IE phenotype was due to an attachment defect. Moreover, differences in cellular (p)ppGpp levels did not affect extracellular gelatinase activity but significantly impaired enterococcal invasion of human coronary artery endothelial cells. Taken together, this study uncovers for the first time the fact that differences in basal (p)ppGpp levels, rather than the stringent response, differentially affect processes that contribute to the pathogenesis of IE.
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Affiliation(s)
- Cristina Colomer-Winter
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Anthony O. Gaca
- Center for Oral Biology and Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
- Present address: Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA
| | - Olivia N. Chuang-Smith
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
- Present address: Bridge to MD and Pathway to American University of Antigua (AUA) Programs, Manipal Education Americas, LLC, New York, NY, USA
| | - José A. Lemos
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, FL, USA
| | - Kristi L. Frank
- Department of Microbiology and Immunology, University of Minnesota Medical School, Minneapolis, MN, USA
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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Expression of Adhesive Pili and the Collagen-Binding Adhesin Ace Is Activated by ArgR Family Transcription Factors in Enterococcus faecalis. J Bacteriol 2018; 200:JB.00269-18. [PMID: 29986940 DOI: 10.1128/jb.00269-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 06/29/2018] [Indexed: 12/15/2022] Open
Abstract
It was shown previously that the disruption of the ahrC gene encoding a predicted ArgR family transcription factor results in a severe defect in biofilm formation in vitro, as well as a significant attenuation of virulence of Enterococcus faecalis strain OG1RF in multiple experimental infection models. Using transcriptome sequencing (RNA-seq), we observed ahrC-dependent changes in the expression of more than 20 genes. AhrC-repressed genes included predicted determinants of arginine catabolism and several other metabolic genes and predicted transporters, while AhrC-activated genes included determinants involved in the production of surface protein adhesins. Most notably, the structural and regulatory genes of the ebp locus encoding adhesive pili were positively regulated, as well as the ace gene, encoding a collagen-binding adhesin. Using lacZ transcription reporter fusions, we determined that ahrC and a second argR transcription factor gene, argR2, both function to activate the expression of ebpR, which directly activates the transcription of the pilus structural genes. Our data suggest that in the wild-type E. faecalis, the low levels of EbpR limit the expression of pili and that biofilm biomass is also limited by the amount of pili expressed by the bacteria. The expression of ace is similarly enhanced by AhrC and ArgR2, but ace expression is not dependent on EbpR. Our results demonstrate the existence of novel regulatory cascades controlled by a pair of ArgR family transcription factors that might function as a heteromeric protein complex.IMPORTANCE Cell surface adhesins play critical roles in the formation of biofilms, host colonization, and the pathogenesis of opportunistic infections by Enterococcus faecalis Here, we present new results showing that the expression of two major enterococcal surface adhesins, ebp pili, and the collagen-binding protein Ace is positively regulated at the transcription level by two argR family transcription factors, AhrC and ArgR2. In the case of pili, the direct target of regulation is the ebpR gene, previously shown to activate the transcription of the pilus structural genes, while the activation of ace transcription appears to be directly impacted by the two ArgR proteins. These transcription factors may represent new targets for blocking enterococcal infections.
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25
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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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26
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Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract. Microbiol Spectr 2017; 4. [PMID: 27227294 DOI: 10.1128/microbiolspec.uti-0012-2012] [Citation(s) in RCA: 195] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gram-positive bacteria are a common cause of urinary-tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI.
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27
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Rashid R, Cazenave-Gassiot A, Gao IH, Nair ZJ, Kumar JK, Gao L, Kline KA, Wenk MR. Comprehensive analysis of phospholipids and glycolipids in the opportunistic pathogen Enterococcus faecalis. PLoS One 2017; 12:e0175886. [PMID: 28423018 PMCID: PMC5397010 DOI: 10.1371/journal.pone.0175886] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 04/02/2017] [Indexed: 02/07/2023] Open
Abstract
Enterococcus faecalis is a Gram-positive, opportunistic, pathogenic bacterium that causes a significant number of antibiotic-resistant infections in hospitalized patients. The development of antibiotic resistance in hospital-associated pathogens is a formidable public health threat. In E. faecalis and other Gram-positive pathogens, correlations exist between lipid composition and antibiotic resistance. Resistance to the last-resort antibiotic daptomycin is accompanied by a decrease in phosphatidylglycerol (PG) levels, whereas multiple peptide resistance factor (MprF) converts anionic PG into cationic lysyl-PG via a trans-esterification reaction, providing resistance to cationic antimicrobial peptides. Unlike previous studies that relied on thin layer chromatography and spectrophotometry, we have performed liquid chromatography-tandem mass spectrometry (LC-MS/MS) directly on lipids extracted from E. faecalis, and quantified the phospholipids through multiple reaction monitoring (MRM). In the daptomycin-sensitive E. faecalis strain OG1RF, we have identified 17 PGs, 8 lysyl-PGs (LPGs), 23 cardiolipins (CL), 3 glycerophospho-diglucosyl-diacylglycerols (GPDGDAG), 5 diglucosyl-diacylglycerols (DGDAG), 3 diacylglycerols (DAGs), and 4 triacylglycerols (TAGs). We have quantified PG and shown that PG levels vary during growth of E. faecalis in vitro. We also show that two daptomycin-resistant (DapR) strains of E. faecalis have substantially lower levels of PG and LPG levels. Since LPG levels in these strains are lower, daptomycin resistance is likely due to the reduction in PG. This lipidome map is the first comprehensive analysis of membrane phospholipids and glycolipids in the important human pathogen E. faecalis, for which antimicrobial resistance and altered lipid homeostasis have been intimately linked.
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Affiliation(s)
- Rafi Rashid
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Amaury Cazenave-Gassiot
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Iris H. Gao
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Zeus J. Nair
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Jaspal K. Kumar
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Liang Gao
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Life Sciences Institute, National University of Singapore, Singapore, Singapore
| | - Kimberly A. Kline
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
- * E-mail: (KAK); (MRW)
| | - Markus R. Wenk
- Singapore Lipidomics Incubator, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
- * E-mail: (KAK); (MRW)
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28
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Arena MP, Capozzi V, Spano G, Fiocco D. The potential of lactic acid bacteria to colonize biotic and abiotic surfaces and the investigation of their interactions and mechanisms. Appl Microbiol Biotechnol 2017; 101:2641-2657. [PMID: 28213732 DOI: 10.1007/s00253-017-8182-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/01/2017] [Accepted: 02/03/2017] [Indexed: 12/23/2022]
Abstract
Lactic acid bacteria (LAB) are a heterogeneous group of Gram-positive bacteria that comprise several species which have evolved in close association with humans (food and lifestyle). While their use to ferment food dates back to very ancient times, in the last decades, LAB have attracted much attention for their documented beneficial properties and for potential biomedical applications. Some LAB are commensal that colonize, stably or transiently, host mucosal surfaces, inlcuding the gut, where they may contribute to host health. In this review, we present and discuss the main factors enabling LAB adaptation to such lifestyle, including the gene reprogramming accompanying gut colonization, the specific bacterial components involved in adhesion and interaction with host, and how the gut niche has shaped the genome of intestine-adapted species. Moreover, the capacity of LAB to colonize abiotic surfaces by forming structured communities, i.e., biofilms, is briefly discussed, taking into account the main bacterial and environmental factors involved, particularly in relation to food-related environments. The vast spread of LAB surface-associated communities and the ability to control their occurrence hold great potentials for human health and food safety biotechnologies.
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Affiliation(s)
- Mattia Pia Arena
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy
| | - Vittorio Capozzi
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy
| | - Giuseppe Spano
- Department of Agriculture, Food and Environment Sciences, University of Foggia, via Napoli 25, 71122, Foggia, Italy.
| | - Daniela Fiocco
- Department of Clinical and Experimental Medicine, University of Foggia, Viale Pinto 1, 71122, Foggia, Italy
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Woods SE, Lieberman MT, Lebreton F, Trowel E, de la Fuente-Núñez C, Dzink-Fox J, Gilmore MS, Fox JG. Characterization of Multi-Drug Resistant Enterococcus faecalis Isolated from Cephalic Recording Chambers in Research Macaques (Macaca spp.). PLoS One 2017; 12:e0169293. [PMID: 28081148 PMCID: PMC5231353 DOI: 10.1371/journal.pone.0169293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/14/2016] [Indexed: 11/19/2022] Open
Abstract
Nonhuman primates are commonly used for cognitive neuroscience research and often surgically implanted with cephalic recording chambers for electrophysiological recording. Aerobic bacterial cultures from 25 macaques identified 72 bacterial isolates, including 15 Enterococcus faecalis isolates. The E. faecalis isolates displayed multi-drug resistant phenotypes, with resistance to ciprofloxacin, enrofloxacin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, bacitracin, and erythromycin, as well as high-level aminoglycoside resistance. Multi-locus sequence typing showed that most belonged to two E. faecalis sequence types (ST): ST 4 and ST 55. The genomes of three representative isolates were sequenced to identify genes encoding antimicrobial resistances and other traits. Antimicrobial resistance genes identified included aac(6’)-aph(2”), aph(3’)-III, str, ant(6)-Ia, tetM, tetS, tetL, ermB, bcrABR, cat, and dfrG, and polymorphisms in parC (S80I) and gyrA (S83I) were observed. These isolates also harbored virulence factors including the cytolysin toxin genes in ST 4 isolates, as well as multiple biofilm-associated genes (esp, agg, ace, SrtA, gelE, ebpABC), hyaluronidases (hylA, hylB), and other survival genes (ElrA, tpx). Crystal violet biofilm assays confirmed that ST 4 isolates produced more biofilm than ST 55 isolates. The abundance of antimicrobial resistance and virulence factor genes in the ST 4 isolates likely relates to the loss of CRISPR-cas. This macaque colony represents a unique model for studying E. faecalis infection associated with indwelling devices, and provides an opportunity to understand the basis of persistence of this pathogen in a healthcare setting.
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Affiliation(s)
- Stephanie E. Woods
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Mia T. Lieberman
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- * E-mail:
| | - Francois Lebreton
- Departments of Ophthalmology, and Microbiology and Immunobiology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston Massachusetts, United States of America
| | - Elise Trowel
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - César de la Fuente-Núñez
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Synthetic Biology Group, MIT Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge Massachusetts, United States of America
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, United States of America
- Harvard Biophysics Program, Harvard University, Boston, Massachusetts, United States of America
- The Center for Microbiome Informatics and Therapeutics, Cambridge, Massachusetts, United States of America
| | - Joanne Dzink-Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Michael S. Gilmore
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - James G. Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
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Lim SY, Yap KP, Teh CSJ, Jabar KA, Thong KL. Comparative genome analysis of multiple vancomycin-resistant Enterococcus faecium isolated from two fatal cases. INFECTION GENETICS AND EVOLUTION 2017; 49:55-65. [PMID: 28039075 DOI: 10.1016/j.meegid.2016.12.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/22/2016] [Accepted: 12/25/2016] [Indexed: 12/31/2022]
Abstract
Enterococcus faecium is both a commensal of the human intestinal tract and an opportunistic pathogen. The increasing incidence of enterococcal infections is mainly due to the ability of this organism to develop resistance to multiple antibiotics, including vancomycin. The aim of this study was to perform comparative genome analyses on four vancomycin-resistant Enterococcus faecium (VREfm) strains isolated from two fatal cases in a tertiary hospital in Malaysia. Two sequence types, ST80 and ST203, were identified which belong to the clinically important clonal complex (CC) 17. This is the first report on the emergence of ST80 strains in Malaysia. Three of the studied strains (VREr5, VREr6, VREr7) were each isolated from different body sites of a single patient (patient Y) and had different PFGE patterns. While VREr6 and VREr7 were phenotypically and genotypically similar, the initial isolate, VREr5, was found to be more similar to VRE2 isolated from another patient (patient X), in terms of the genome contents, sequence types and phylogenomic relationship. Both the clinical records and genome sequence data suggested that patient Y was infected by multiple strains from different clones and the strain that infected patient Y could have derived from the same clone from patient X. These multidrug resistant strains harbored a number of virulence genes such as the epa locus and pilus-associated genes which could enhance their persistence. Apart from that, a homolog of E. faecalis bee locus was identified in VREr5 which might be involved in biofilm formation. Overall, our comparative genomic analyses had provided insight into the genetic relatedness, as well as the virulence potential, of the four clinical strains.
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Affiliation(s)
- Shu Yong Lim
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Kien-Pong Yap
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Cindy Shuan Ju Teh
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kartini Abdul Jabar
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kwai Lin Thong
- Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
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Abstract
Urinary tract infections (UTI) are among the most common bacterial infections in humans, affecting millions of people every year. UTI cause significant morbidity in women throughout their lifespan, in infant boys, in older men, in individuals with underlying urinary tract abnormalities, and in those that require long-term urethral catheterization, such as patients with spinal cord injuries or incapacitated individuals living in nursing homes. Serious sequelae include frequent recurrences, pyelonephritis with sepsis, renal damage in young children, pre-term birth, and complications of frequent antimicrobial use including high-level antibiotic resistance and Clostridium difficile colitis. Uropathogenic E. coli (UPEC) cause the vast majority of UTI, but less common pathogens such as Enterococcus faecalis and other enterococci frequently take advantage of an abnormal or catheterized urinary tract to cause opportunistic infections. While antibiotic therapy has historically been very successful in controlling UTI, the high rate of recurrence remains a major problem, and many individuals suffer from chronically recurring UTI, requiring long-term prophylactic antibiotic regimens to prevent recurrent UTI. Furthermore, the global emergence of multi-drug resistant UPEC in the past ten years spotlights the need for alternative therapeutic and preventative strategies to combat UTI, including anti-infective drug therapies and vaccines. In this chapter, we review recent advances in the field of UTI pathogenesis, with an emphasis on the identification of promising drug and vaccine targets. We then discuss the development of new UTI drugs and vaccines, highlighting the challenges these approaches face and the need for a greater understanding of urinary tract mucosal immunity.
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La Rosa SL, Montealegre MC, Singh KV, Murray BE. Enterococcus faecalis Ebp pili are important for cell-cell aggregation and intraspecies gene transfer. MICROBIOLOGY-SGM 2016; 162:798-802. [PMID: 26967674 DOI: 10.1099/mic.0.000276] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Enterococcus faecalis is an opportunistic pathogen that ranks among the leading causes of biofilm-associated infections. We previously demonstrated that the endocarditis- and biofilm-associated pili (Ebp) of E. faecalis play a major role in biofilm formation, adherence to abiotic surfaces and experimental infections. In this study, derivatives of E. faecalis strain OG1 were engineered to further characterize functions of Ebp pili. Loss of pili resulted in a 36-fold decrease in the number of closely associated cells when OG1RFΔebpABC was mixed with OG1SSpΔebpABC, compared with mixing the Ebp+ parental strains. In addition, using the Ebp+ parental strains as donor and recipient, we found a statistically significant increase (280-360 %, P < 0.05) in the frequency of plasmid transfer versus using Ebp- mutants in the conjugation experiments. These results demonstrate a previously unrecognized role of Ebp pili, namely, as important contributors to microscale cell aggregation and horizontal spread of genetic material.
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Affiliation(s)
- Sabina Leanti La Rosa
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Health Science Center,Houston, Texas,USA
| | - Maria Camila Montealegre
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Health Science Center,Houston, Texas,USA.,Department of Microbiology and Molecular Genetics, University of Texas Health Science Center,Houston, Texas,USA
| | - Kavindra V Singh
- Department of Internal Medicine, Division of Infectious Diseases, University of Texas Health Science Center,Houston, Texas,USA.,Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center,Houston, Texas,USA
| | - Barbara E Murray
- Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Health Science Center,Houston, Texas,USA.,Department of Microbiology and Molecular Genetics, University of Texas Health Science Center,Houston, Texas,USA.,Department of Internal Medicine, Division of Infectious Diseases, University of Texas Health Science Center,Houston, Texas,USA
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Park YG, Jung MC, Song H, Jeong KW, Bang E, Hwang GS, Kim Y. Novel Structural Components Contribute to the High Thermal Stability of Acyl Carrier Protein from Enterococcus faecalis. J Biol Chem 2015; 291:1692-1702. [PMID: 26631734 DOI: 10.1074/jbc.m115.674408] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Indexed: 11/06/2022] Open
Abstract
Enterococcus faecalis is a Gram-positive, commensal bacterium that lives in the gastrointestinal tracts of humans and other mammals. It causes severe infections because of high antibiotic resistance. E. faecalis can endure extremes of temperature and pH. Acyl carrier protein (ACP) is a key element in the biosynthesis of fatty acids responsible for acyl group shuttling and delivery. In this study, to understand the origin of high thermal stabilities of E. faecalis ACP (Ef-ACP), its solution structure was investigated for the first time. CD experiments showed that the melting temperature of Ef-ACP is 78.8 °C, which is much higher than that of Escherichia coli ACP (67.2 °C). The overall structure of Ef-ACP shows the common ACP folding pattern consisting of four α-helices (helix I (residues 3-17), helix II (residues 39-53), helix III (residues 60-64), and helix IV (residues 68-78)) connected by three loops. Unique Ef-ACP structural features include a hydrophobic interaction between Phe(45) in helix II and Phe(18) in the α1α2 loop and a hydrogen bonding between Ser(15) in helix I and Ile(20) in the α1α2 loop, resulting in its high thermal stability. Phe(45)-mediated hydrophobic packing may block acyl chain binding subpocket II entry. Furthermore, Ser(58) in the α2α3 loop in Ef-ACP, which usually constitutes a proline in other ACPs, exhibited slow conformational exchanges, resulting in the movement of the helix III outside the structure to accommodate a longer acyl chain in the acyl binding cavity. These results might provide insights into the development of antibiotics against pathogenic drug-resistant E. faecalis strains.
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Affiliation(s)
- Young-Guen Park
- From the Department of Bioscience and Biotechnology and the Bio/Molecular Informatics Center Konkuk University, Seoul 143-701, Korea and
| | - Min-Cheol Jung
- From the Department of Bioscience and Biotechnology and the Bio/Molecular Informatics Center Konkuk University, Seoul 143-701, Korea and
| | - Heesang Song
- From the Department of Bioscience and Biotechnology and the Bio/Molecular Informatics Center Konkuk University, Seoul 143-701, Korea and
| | - Ki-Woong Jeong
- From the Department of Bioscience and Biotechnology and the Bio/Molecular Informatics Center Konkuk University, Seoul 143-701, Korea and
| | - Eunjung Bang
- the Western Seoul Center, Korea Basic Science Institute, Seoul 120-140, Korea
| | - Geum-Sook Hwang
- the Western Seoul Center, Korea Basic Science Institute, Seoul 120-140, Korea
| | - Yangmee Kim
- From the Department of Bioscience and Biotechnology and the Bio/Molecular Informatics Center Konkuk University, Seoul 143-701, Korea and.
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Abriouel H, Lerma LL, Casado Muñoz MDC, Montoro BP, Kabisch J, Pichner R, Cho GS, Neve H, Fusco V, Franz CMAP, Gálvez A, Benomar N. The controversial nature of the Weissella genus: technological and functional aspects versus whole genome analysis-based pathogenic potential for their application in food and health. Front Microbiol 2015; 6:1197. [PMID: 26579103 PMCID: PMC4621295 DOI: 10.3389/fmicb.2015.01197] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 10/15/2015] [Indexed: 11/21/2022] Open
Abstract
Despite the use of several Weissella (W.) strains for biotechnological and probiotic purposes, certain species of this genus were found to act as opportunistic pathogens, while strains of W. ceti were recognized to be pathogenic for farmed rainbow trout. Herein, we investigated the pathogenic potential of weissellas based on in silico analyses of the 13 whole genome sequences available to date in the NCBI database. Our screening allowed us to find several virulence determinants such as collagen adhesins, aggregation substances, mucus-binding proteins, and hemolysins in some species. Moreover, we detected several antibiotic resistance-encoding genes, whose presence could increase the potential pathogenicity of some strains, but should not be regarded as an excluding trait for beneficial weissellas, as long as these genes are not present on mobile genetic elements. Thus, selection of weissellas intended to be used as starters or for biotechnological or probiotic purposes should be investigated regarding their safety aspects on a strain to strain basis, preferably also by genome sequencing, since nucleotide sequence heterogeneity in virulence and antibiotic resistance genes makes PCR-based screening unreliable for safety assessments. In this sense, the application of W. confusa and W. cibaria strains as starter cultures or as probiotics should be approached with caution, by carefully selecting strains that lack pathogenic potential.
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Affiliation(s)
- Hikmate Abriouel
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
| | - Leyre Lavilla Lerma
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
| | - María Del Carmen Casado Muñoz
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
| | - Beatriz Pérez Montoro
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
| | - Jan Kabisch
- Department of Microbiology and Biotechnology, Federal Research Institute of Nutrition and Food, Max Rubner-Institut , Kiel, Germany
| | - Rohtraud Pichner
- Department of Microbiology and Biotechnology, Federal Research Institute of Nutrition and Food, Max Rubner-Institut , Kiel, Germany
| | - Gyu-Sung Cho
- Department of Microbiology and Biotechnology, Federal Research Institute of Nutrition and Food, Max Rubner-Institut , Kiel, Germany
| | - Horst Neve
- Department of Microbiology and Biotechnology, Federal Research Institute of Nutrition and Food, Max Rubner-Institut , Kiel, Germany
| | - Vincenzina Fusco
- Institute of Sciences of Food Production, National Research Council of Italy , Bari, Italy
| | - Charles M A P Franz
- Department of Microbiology and Biotechnology, Federal Research Institute of Nutrition and Food, Max Rubner-Institut , Kiel, Germany
| | - Antonio Gálvez
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
| | - Nabil Benomar
- Área de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén , Jaén, Spain
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35
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Chahales P, Thanassi DG. Structure, Function, and Assembly of Adhesive Organelles by Uropathogenic Bacteria. Microbiol Spectr 2015; 3:10.1128/microbiolspec.UTI-0018-2013. [PMID: 26542038 PMCID: PMC4638162 DOI: 10.1128/microbiolspec.uti-0018-2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 01/02/2023] Open
Abstract
Bacteria assemble a wide range of adhesive proteins, termed adhesins, to mediate binding to receptors and colonization of surfaces. For pathogenic bacteria, adhesins are critical for early stages of infection, allowing the bacteria to initiate contact with host cells, colonize different tissues, and establish a foothold within the host. The adhesins expressed by a pathogen are also critical for bacterial-bacterial interactions and the formation of bacterial communities, including biofilms. The ability to adhere to host tissues is particularly important for bacteria that colonize sites such as the urinary tract, where the flow of urine functions to maintain sterility by washing away non-adherent pathogens. Adhesins vary from monomeric proteins that are directly anchored to the bacterial surface to polymeric, hair-like fibers that extend out from the cell surface. These latter fibers are termed pili or fimbriae, and were among the first identified virulence factors of uropathogenic Escherichia coli. Studies since then have identified a range of both pilus and non-pilus adhesins that contribute to bacterial colonization of the urinary tract, and have revealed molecular details of the structures, assembly pathways, and functions of these adhesive organelles. In this review, we describe the different types of adhesins expressed by both Gram-negative and Gram-positive uropathogens, what is known about their structures, how they are assembled on the bacterial surface, and the functions of specific adhesins in the pathogenesis of urinary tract infections.
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Affiliation(s)
- Peter Chahales
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
| | - David G Thanassi
- Center for Infectious Diseases and Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794
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The fibronectin-binding protein Fnm contributes to adherence to extracellular matrix components and virulence of Enterococcus faecium. Infect Immun 2015; 83:4653-61. [PMID: 26371130 DOI: 10.1128/iai.00885-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/10/2015] [Indexed: 12/29/2022] Open
Abstract
The interaction between bacteria and fibronectin is believed to play an important role in the pathogenicity of clinically important Gram-positive cocci. In the present study, we identified a gene encoding a predicted fibronectin-binding protein of Enterococcus faecium (fnm), a homologue of Streptococcus pneumoniae pavA, in the genomes of E. faecium strain TX82 and all other sequenced E. faecium isolates. Full-length recombinant Fnm from strain TX82 bound to immobilized fibronectin in a concentration-dependent manner and also appeared to bind collagen type V and laminin, but not other proteins, such as transferrin, heparin, bovine serum albumin, mucin, or collagen IV. We demonstrated that the N-terminal fragment of Fnm is required for full fibronectin binding, since truncation of this region caused a 2.4-fold decrease (P < 0.05) in the adhesion of E. faecium TX82 to fibronectin. Deletion of fnm resulted in a significant reduction (P < 0.001) in the ability of the mutant, TX6128, to bind fibronectin relative to that of the wild-type strain; in situ reconstitution of fnm in the deletion mutant strain restored adherence. In addition, the Δfnm mutant was highly attenuated relative to TX82 (P ≤ 0.0001) in a mixed-inoculum rat endocarditis model. Taken together, these results demonstrate that Fnm affects the adherence of E. faecium to fibronectin and is important in the pathogenesis of experimental endocarditis.
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The fibronectin-binding protein EfbA contributes to pathogenesis and protects against infective endocarditis caused by Enterococcus faecalis. Infect Immun 2015; 83:4487-94. [PMID: 26351286 DOI: 10.1128/iai.00884-15] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/01/2015] [Indexed: 12/24/2022] Open
Abstract
EfbA is a PavA-like fibronectin adhesin of Enterococcus faecalis previously shown to be important in experimental urinary tract infection. Here, we expressed and purified the E. faecalis OG1RF EfbA and confirmed that this protein binds with high affinity to immobilized fibronectin, collagen I, and collagen V. We constructed an efbA deletion mutant and demonstrated that its virulence was significantly attenuated (P < 0.0006) versus the wild type in a mixed inoculum rat endocarditis model. Furthermore, efbA deletion resulted in diminished ability to bind fibronectin (P < 0.0001) and reduced biofilm (P < 0.001). Reintroduction of efbA into the original chromosomal location restored virulence, adherence to fibronectin, and biofilm formation to wild-type levels. Finally, vaccination of rats with purified recombinant EfbA protein protected against OG1RF endocarditis (P = 0.008 versus control). Taken together, our results demonstrate that EfbA is an important factor involved in E. faecalis endocarditis and that rEfbA immunization is effective in preventing such infection, likely by interfering with bacterial adherence.
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Frank KL, Vergidis P, Brinkman CL, Greenwood Quaintance KE, Barnes AMT, Mandrekar JN, Schlievert PM, Dunny GM, Patel R. Evaluation of the Enterococcus faecalis Biofilm-Associated Virulence Factors AhrC and Eep in Rat Foreign Body Osteomyelitis and In Vitro Biofilm-Associated Antimicrobial Resistance. PLoS One 2015; 10:e0130187. [PMID: 26076451 PMCID: PMC4467866 DOI: 10.1371/journal.pone.0130187] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/18/2015] [Indexed: 02/01/2023] Open
Abstract
Enterococcus faecalis can cause healthcare-associated biofilm infections, including those of orthopedic devices. Treatment of enterococcal prosthetic joint infection is difficult, in part, due to biofilm-associated antimicrobial resistance. We previously showed that the E. faecalis OG1RF genes ahrC and eep are in vitro biofilm determinants and virulence factors in animal models of endocarditis and catheter-associated urinary tract infection. In this study, we evaluated the role of these genes in a rat acute foreign body osteomyelitis model and in in vitro biofilm-associated antimicrobial resistance. Osteomyelitis was established for one week following the implantation of stainless steel orthopedic wires inoculated with E. faecalis strains OG1RF, ΩahrC, and ∆eep into the proximal tibiae of rats. The median bacterial loads recovered from bones and wires did not differ significantly between the strains at multiple inoculum concentrations. We hypothesize that factors present at the infection site that affect biofilm formation, such as the presence or absence of shear force, may account for the differences in attenuation in the various animal models we have used to study the ΩahrC and ∆eep strains. No differences among the three strains were observed in the planktonic and biofilm antimicrobial susceptibilities to ampicillin, vancomycin, daptomycin, linezolid, and tetracycline. These findings suggest that neither ahrC nor eep directly contribute to E. faecalis biofilm-associated antimicrobial resistance. Notably, the experimental evidence that the biofilm attachment mutant ΩahrC displays biofilm-associated antimicrobial resistance suggests that surface colonization alone is sufficient for E. faecalis cells to acquire the biofilm antimicrobial resistance phenotype.
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Affiliation(s)
- Kristi L. Frank
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Paschalis Vergidis
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Cassandra L. Brinkman
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Kerryl E. Greenwood Quaintance
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Aaron M. T. Barnes
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jayawant N. Mandrekar
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Patrick M. Schlievert
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Gary M. Dunny
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Robin Patel
- Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, United States of America
- Division of Infectious Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
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Flores-Mireles AL, Pinkner JS, Caparon MG, Hultgren SJ. EbpA vaccine antibodies block binding of Enterococcus faecalis to fibrinogen to prevent catheter-associated bladder infection in mice. Sci Transl Med 2015; 6:254ra127. [PMID: 25232179 DOI: 10.1126/scitranslmed.3009384] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Enterococci bacteria are a frequent cause of catheter-associated urinary tract infections, the most common type of hospital-acquired infection. Treatment has become increasingly challenging because of the emergence of multiantibiotic-resistant enterococcal strains and their ability to form biofilms on catheters. We identified and targeted a critical step in biofilm formation and developed a vaccine that prevents catheter-associated urinary tract infections in mice. In the murine model, formation of catheter-associated biofilms by Enterococcus faecalis depends on EbpA, which is the minor subunit at the tip of a heteropolymeric surface fiber known as the endocarditis- and biofilm-associated pilus (Ebp). We show that EbpA is an adhesin that mediates bacterial attachment to host fibrinogen, which is released and deposited on catheters after introduction of the catheter into the mouse bladder. Fibrinogen-binding activity resides in the amino-terminal domain of EbpA (EbpA(NTD)), and vaccination with EbpA and EbpA(NTD), but not its carboxyl-terminal domain or other Ebp subunits, inhibited biofilm formation in vivo and protected against catheter-associated urinary tract infection. Analyses in vitro demonstrated that protection was associated with a serum antibody response that blocked EbpA binding to fibrinogen and the formation of a fibrinogen-dependent biofilm on catheters. This approach may provide a new strategy for the prevention of catheter-associated urinary tract infections.
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Affiliation(s)
- Ana L Flores-Mireles
- Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
| | - Jerome S Pinkner
- Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110-1093, USA
| | - Michael G Caparon
- Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
| | - Scott J Hultgren
- Department of Molecular Microbiology and Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
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40
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The Enterococcus faecalis EbpA Pilus Protein: Attenuation of Expression, Biofilm Formation, and Adherence to Fibrinogen Start with the Rare Initiation Codon ATT. mBio 2015; 6:e00467-15. [PMID: 26015496 PMCID: PMC4447247 DOI: 10.1128/mbio.00467-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The endocarditis and biofilm-associated pili (Ebp) are important in Enterococcus faecalis pathogenesis, and the pilus tip, EbpA, has been shown to play a major role in pilus biogenesis, biofilm formation, and experimental infections. Based on in silico analyses, we previously predicted that ATT is the EbpA translational start codon, not the ATG codon, 120 bp downstream of ATT, which is annotated as the translational start. ATT is rarely used to initiate protein synthesis, leading to our hypothesis that this codon participates in translational regulation of Ebp production. To investigate this possibility, site-directed mutagenesis was used to introduce consecutive stop codons in place of two lysines at positions 5 and 6 from the ATT, to replace the ATT codon in situ with ATG, and then to revert this ATG to ATT; translational fusions of ebpA to lacZ were also constructed to investigate the effect of these start codons on translation. Our results showed that the annotated ATG does not start translation of EbpA, implicating ATT as the start codon; moreover, the presence of ATT, compared to the engineered ATG, resulted in significantly decreased EbpA surface display, attenuated biofilm, and reduced adherence to fibrinogen. Corroborating these findings, the translational fusion with the native ATT as the initiation codon showed significantly decreased expression of β-galactosidase compared to the construct with ATG in place of ATT. Thus, these results demonstrate that the rare initiation codon of EbpA negatively regulates EbpA surface display and negatively affects Ebp-associated functions, including biofilm and adherence to fibrinogen. IMPORTANCE Enterococcus faecalis is among the leading causes of serious infections in the hospital setting, and the endocarditis and biofilm-associated pili (Ebp) have been shown to play significant roles in E. faecalis pathogenesis. Understanding the regulation of virulence is important for the development of new approaches to counteract multidrug-resistant pathogens. We previously predicted that ATT, which has been reported to start protein synthesis only in rare instances, is the most likely translational start codon of EbpA in E. faecalis. Here, we demonstrate that ATT is the initiation codon of EbpA and, relative to a constructed ATG start codon, results in smaller amounts of EbpA on the surface of the cells, attenuating biofilm formation and fibrinogen adherence, phenotypes associated with the ability of E. faecalis to cause infections. This provides the first example of pilus regulation through the use of an ATT initiation codon.
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The two-component system GrvRS (EtaRS) regulates ace expression in Enterococcus faecalis OG1RF. Infect Immun 2014; 83:389-95. [PMID: 25385790 DOI: 10.1128/iai.02587-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Expression of ace (adhesin to collagen of Enterococcus faecalis), encoding a virulence factor in endocarditis and urinary tract infection models, has been shown to increase under certain conditions, such as in the presence of serum, bile salts, urine, and collagen and at 46 °C. However, the mechanism of ace/Ace regulation under different conditions is still unknown. In this study, we identified a two-component regulatory system GrvRS as the main regulator of ace expression under these stress conditions. Using Northern hybridization and β-galactosidase assays of an ace promoter-lacZ fusion, we found transcription of ace to be virtually absent in a grvR deletion mutant under the conditions that increase ace expression in wild-type OG1RF and in the complemented strain. Moreover, a grvR mutant revealed decreased collagen binding and biofilm formation as well as attenuation in a murine urinary tract infection model. Here we show that GrvR plays a major role in control of ace expression and E. faecalis virulence.
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Wobser D, Ali L, Grohmann E, Huebner J, Sakinc T. A novel role for D-alanylation of lipoteichoic acid of enterococcus faecalis in urinary tract infection. PLoS One 2014; 9:e107827. [PMID: 25296179 PMCID: PMC4189791 DOI: 10.1371/journal.pone.0107827] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/20/2014] [Indexed: 11/19/2022] Open
Abstract
Background Enterococci are the third most common cause of healthcare-associated infections, which include urinary tract infections, bacteremia and endocarditis. Cell-surface structures such as lipoteichoic acid (LTA) have been poorly examined in E. faecalis, especially with respect to urinary tract infections (UTIs). The dlt operon is responsible for the D-alanylation of LTA and includes the gene dltA, which encodes the D-alanyl carrier protein ligase (Dcl). The involvement of LTA in UTI infection by E. faecalis has not been studied so far. Here, we examined the role of teichoic acid alanylation in the adhesion of enterococci to uroepithelial cells. Results In a mouse model of urinary tract infection, we showed that E. faecalis 12030ΔdltA mutant colonizes uroepithelial surfaces more efficiently than wild type bacteria. We also demonstrated that this mutant adhered four fold better to human bladder carcinoma cell line T24 compared to the wild type strain. Bacterial adherence could be significantly inhibited by purified lipoteichoic acid (LTA) and inhibition was specific. Conclusion In contrast to bacteraemia model and adherence to colon surfaces, E. faecalis 12030ΔdltA mutant colonized uroepithelial surfaces more efficiently than wild-type bacteria. In the case of the uroepithelial surface the adherence to specific host cells could be prevented by purified LTA. Our results therefore suggest a novel function of alanylation of LTA in E. faecalis.
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Affiliation(s)
- Dominique Wobser
- Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany
| | - Liaqat Ali
- Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany
- Faculty of Biology, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Elisabeth Grohmann
- Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany
- Faculty of Biology, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Johannes Huebner
- Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany
- Division of Pediatric Infectious Diseases, Dr. Von Hauner Children's Hospital, Ludwig Maximilian University Munich, Munich, Germany
| | - Türkan Sakinc
- Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, Freiburg, Germany
- * E-mail:
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Leuconostoc mesenteroides SJRP55: A Bacteriocinogenic Strain Isolated from Brazilian Water Buffalo Mozzarella Cheese. Probiotics Antimicrob Proteins 2014; 6:186-97. [DOI: 10.1007/s12602-014-9163-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Diederich AK, Wobser D, Spiess M, Sava IG, Huebner J, Sakιnç T. Role of glycolipids in the pathogenesis of Enterococcus faecalis urinary tract infection. PLoS One 2014; 9:e96295. [PMID: 24806450 PMCID: PMC4012979 DOI: 10.1371/journal.pone.0096295] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 04/06/2014] [Indexed: 01/28/2023] Open
Abstract
Background After uropathogenic Escherichia coli (UPEC), Enterococcus faecalis is the second most common pathogen causing urinary tract infections. Monoglucosyl-diacylglycerol (MGlcDAG) and diglucosyl-diacylglycerol (DGlcDAG) are the main glycolipids of the E. faecalis cell membrane. Examination of two mutants in genes bgsB and bgsA (both glycosyltransferases) showed that these genes are involved in cell membrane glycolipid biosynthesis, and that their inactivation leads to loss of glycolipids DGlcDAG (bgsA) or both MGlcDAG and DGlcDAG (bgsB). Here we investigate the function of bgsB and bgsA regarding their role in the pathogenesis in a mouse model of urinary tract infection and in bacterial adhesion to T24 bladder epithelial cells. Results In a mouse model of urinary tract infection, we showed that E. faecalis 12030ΔbgsB and E. faecalis 12030ΔbgsA mutants, colonize uroepithelial surfaces more efficiently than wild-type bacteria. We also demonstrated that these mutants showed a more than three-fold increased binding to human bladder carcinoma cells line T24 compared to the wild-type strain. Bacterial binding could be specifically inhibited by purified glycolipids. Lipoteichoic acid (LTA), wall-teichoic acid (WTA), and glycosaminoglycans (GAGs) were not significantly involved in binding of E. faecalis to the bladder epithelial cell line. Conclusions Our data show that the deletion of bgsB and bgsA and the absence of the major glycolipid diglucosyl-diacylglycerol increases colonization and binding to uroepithelial cells. We hypothesize that secreted diglucosyl-diacylglycerol blocks host binding sites, thereby preventing bacterial adhesion. Further experiments will be needed to clarify the exact mechanism underlying the adhesion through glycolipids and their cognate receptors.
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Affiliation(s)
| | - Dominique Wobser
- Division of Infectious Diseases, University Hospital Freiburg, Freiburg, Germany
| | - Meike Spiess
- Division of Infectious Diseases, University Hospital Freiburg, Freiburg, Germany
| | - Irina G. Sava
- Nutrition and Immunology, Research Centre for Nutrition and Food Science, Technical University Munich, Munich, Germany
| | - Johannes Huebner
- Division of Infectious Diseases, University Hospital Freiburg, Freiburg, Germany
- Division of Pediatric Infectious Diseases, Dr. Von Hauner Children's Hospital, Ludwig Maximilian University Munich, Munich, Germany
- * E-mail:
| | - Türkân Sakιnç
- Division of Infectious Diseases, University Hospital Freiburg, Freiburg, Germany
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Cell-wall glycolipid mutations and their effects on virulence of E. faecalis in a rat model of infective endocarditis. PLoS One 2014; 9:e91863. [PMID: 24637922 PMCID: PMC3956713 DOI: 10.1371/journal.pone.0091863] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 02/17/2014] [Indexed: 11/19/2022] Open
Abstract
Enterococci are among the major pathogens implicated in cardiac infections and biofilm formation. E. faecalis has been shown to play an important role in infectious endocarditis. Several distinct mechanisms for biofilm formation have been identified in E. faecalis. Our group has previously characterized two distinct bacterial glucosyltransferases playing key roles in the production of the major cell wall glycolipids and leading to reduced biofilm production. To assess if this mechanism is involved in the pathogenesis of enterococcal endocarditis we compared the wild-type strain of E. faecalis 12030 with two mutants in gene EF2891 and EF2890 respectively in a rat model of infective endocarditis. The results showed less endocarditic lesions and reduced colony counts per vegetation in the two mutants. indicating that the modification of bacterial surface lipids results in significantly reduced virulence in infective endocarditis. These results underscore the important role of biofilm formation in the pathogenicity of enterococcal endocarditis and may indicate an interesting target for novel therapeutic strategies.
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Danne C, Dubrac S, Trieu-Cuot P, Dramsi S. Single cell stochastic regulation of pilus phase variation by an attenuation-like mechanism. PLoS Pathog 2014; 10:e1003860. [PMID: 24453966 PMCID: PMC3894217 DOI: 10.1371/journal.ppat.1003860] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Accepted: 11/18/2013] [Indexed: 12/17/2022] Open
Abstract
The molecular triggers leading to virulence of a number of human-adapted commensal bacteria such as Streptococcus gallolyticus are largely unknown. This opportunistic pathogen is responsible for endocarditis in the elderly and associated with colorectal cancer. Colonization of damaged host tissues with exposed collagen, such as cardiac valves and pre-cancerous polyps, is mediated by appendages referred to as Pil1 pili. Populations of S. gallolyticus are heterogeneous with the majority of cells weakly piliated while a smaller fraction is hyper piliated. We provide genetic evidences that heterogeneous pil1 expression depends on a phase variation mechanism involving addition/deletion of GCAGA repeats that modifies the length of an upstream leader peptide. Synthesis of longer leader peptides potentiates the transcription of the pil1 genes through ribosome-induced destabilization of a premature stem-loop transcription terminator. This study describes, at the molecular level, a new regulatory mechanism combining phase variation in a leader peptide-encoding gene and transcription attenuation. This simple and robust mechanism controls a stochastic heterogeneous pilus expression, which is important for evading the host immune system while ensuring optimal tissue colonization. Streptococcus gallolyticus (formely known as S. bovis biotype I) is an emerging cause of septicemia and endocarditis in the elderly. Intriguingly, epidemiological studies revealed a strong association, up to 65%, between endocarditis due to S. gallolyticus and colorectal malignancies. Whether S. gallolyticus infection is a cause or a consequence of colon cancer remains to be investigated. We previously showed that colonization of damaged cardiac valves with exposed collagen is mediated by the Pil1 pilus in S. gallolyticus. In the present work, we report that Pil1 is heterogeneously expressed at the single cell level, giving rise to two distinct bacterial subpopulations, a majority of weakly piliated cells and a minority of hyper-piliated cells. We have characterized, at the molecular level, a novel regulatory mechanism responsible for Pil1 heterogeneous expression combining phase variation in the leader peptide and transcriptional attenuation. Pili are highly immunogenic proteins proposed as vaccine candidate in pathogenic streptococci whose expression involves a fitness cost due to the selective pressure of host immune responses. Hence, this robust and simple system mitigates susceptibility to immune defenses while ensuring optimal colonization of host tissues.
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Affiliation(s)
- Camille Danne
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
- Université Paris Diderot-Sorbonne Paris Cité, Paris, France
| | - Sarah Dubrac
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
| | - Shaynoor Dramsi
- Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram positif, Paris, France
- CNRS ERL 3526, Paris, France
- * E-mail:
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Pilin and sortase residues critical for endocarditis- and biofilm-associated pilus biogenesis in Enterococcus faecalis. J Bacteriol 2013; 195:4484-95. [PMID: 23913319 DOI: 10.1128/jb.00451-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Enterococci commonly cause hospital-acquired infections, such as infective endocarditis and catheter-associated urinary tract infections. In animal models of these infections, a long hairlike extracellular protein fiber known as the endocarditis- and biofilm-associated (Ebp) pilus is an important virulence factor for Enterococcus faecalis. For Ebp and other sortase-assembled pili, the pilus-associated sortases are essential for fiber formation as they create covalent isopeptide bonds between the sortase recognition motif and the pilin-like motif of the pilus subunits. However, the molecular requirements governing the incorporation of the three pilus subunits (EbpA, EbpB, and EbpC) have not been investigated in E. faecalis. Here, we show that a Lys residue within the pilin-like motif of the EbpC subunit was necessary for EbpC polymerization. However, incorporation of EbpA into the pilus fiber only required its sortase recognition motif (LPXTG), while incorporation of EbpB only required its pilin-like motif. Only the sortase recognition motif would be required for incorporation of the pilus tip subunit, while incorporation of the base subunit would only require the pilin recognition motif. Thus, these data support a model with EbpA at the tip and EbpB at the base of an EbpC polymer. In addition, the housekeeping sortase, SrtA, was found to process EbpB and its predicted catalytic Cys residue was required for efficient cell wall anchoring of mature Ebp pili. Thus, we have defined molecular interactions involved in fiber polymerization, minor subunit organization, and pilus subcellular compartmentalization in the E. faecalis Ebp pilus system. These studies advance our understanding of unique molecular mechanisms of sortase-assembled pilus biogenesis.
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Contribution of individual Ebp Pilus subunits of Enterococcus faecalis OG1RF to pilus biogenesis, biofilm formation and urinary tract infection. PLoS One 2013; 8:e68813. [PMID: 23874774 PMCID: PMC3708956 DOI: 10.1371/journal.pone.0068813] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 05/31/2013] [Indexed: 11/25/2022] Open
Abstract
The endocarditis and biofilm-associated pilus (Ebp) operon is a component of the core genome of Enterococcus faecalis that has been shown to be important for biofilm formation, adherence to host fibrinogen, collagen and platelets, and in experimental endocarditis and urinary tract infection models. Here, we created single and double deletion mutants of the pilus subunits and sortases; next, by combining western blotting, immunoelectron microscopy, and using ebpR in trans to increase pilus production, we identified EbpA as the tip pilin and EbpB as anchor at the pilus base, the latter attached to cell wall by the housekeeping sortase, SrtA. We also confirmed EbpC and Bps as the major pilin and pilin-specific sortase, respectively, both required for pilus polymerization. Interestingly, pilus length was increased and the number of pili decreased by deleting ebpA, while control overexpression of ebpA in trans restored wild-type levels, suggesting a dual role for EbpA in both initiation and termination of pilus polymerization. We next investigated the contribution of each pilin subunit to biofilm formation and UTI. Significant reduction in biofilm formation was observed with deletion of ebpA or ebpC (P<0.001) while ebpB was found to be dispensable; a similar result was seen in kidney CFUs in experimental UTI (ΔebpA, ΔebpC, P≤0.0093; ΔebpB, non-significant, each vs. OG1RF). Hence, our data provide important structural and functional information about these ubiquitous E. faecalis pili and, based on their demonstrated importance in biofilm and infection, suggest EbpA and EbpC as potential targets for antibody-based therapeutic approaches.
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Cohen ALV, Roh JH, Nallapareddy SR, Höök M, Murray BE. Expression of the collagen adhesin ace by Enterococcus faecalis strain OG1RF is not repressed by Ers but requires the Ers box. FEMS Microbiol Lett 2013; 344:18-24. [PMID: 23551253 DOI: 10.1111/1574-6968.12146] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/26/2013] [Accepted: 03/29/2013] [Indexed: 11/30/2022] Open
Abstract
Expression of adhesin to collagen of Enterococcus faecalis (ace), a known virulence factor, is increased by environmental signals such as the presence of serum, high temperature, and bile salts. Currently, the enterococcal regulator of survival (Ers) of E. faecalis strain JH2-2 is the only reported repressor of ace. Here, we show that for strain OG1RF, Ers is not involved in the regulation of ace. Our data showed similar levels of ace expression by OG1RF and its Δers derivative in the presence of bile salts, serum, and high temperature. Using ace promoter-lacZ fusions and site-directed mutagenesis, we confirmed these results and further showed that, while the previously designated Ers box is important for increased expression from the ace promoter of OG1RF, the region responsible for the increase is bigger than the Ers box. In summary, these results indicate that, in strain OG1RF, Ers is not a repressor of ace expression. Although JH2-2 and OG1RF differ by six nucleotides in the region upstream of ace as well as in production of Fsr and gelatinase, the reason(s) for the difference in ace expression between JH2-2 and OG1RF and for increased ace expression in bile, serum and at 46 °C remain(s) to be determined.
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Affiliation(s)
- Ana Luisa V Cohen
- Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical School, Houston, TX 77030, USA
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Tan Q, Xu H, Aguilar ZP, Peng S, Dong S, Wang B, Li P, Chen T, Xu F, Wei H. Safety Assessment and Probiotic Evaluation ofEnterococcus FaeciumYF5 Isolated from Sourdough. J Food Sci 2013; 78:M587-93. [DOI: 10.1111/1750-3841.12079] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 01/14/2013] [Indexed: 12/18/2022]
Affiliation(s)
- Qianglai Tan
- State Key Laboratory of Food Science and Technology; Nanchang Univ., 235 Nanjing Donglu, Nanchang 330047, P.R. China; Jiangxi-OAI Joint Research Inst., Nanchang Univ.; Nanchang; 330047, P.R.; China
| | - Hengyi Xu
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
| | - Zoraida P. Aguilar
- Dept. of Immunochemistry, Covance Laboratories, Inc.; Chantilly VA; 20150; U.S.A
| | - Shanshan Peng
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
| | - Suqin Dong
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
| | - Baogui Wang
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
| | - Ping Li
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
| | - Tingtao Chen
- Jiangxi-OAI Joint Research Inst.; Nanchang Univ.; Nanchang 330047, P.R.; China
| | - Feng Xu
- Jiangxi-OAI Joint Research Inst.; Nanchang Univ.; Nanchang 330047, P.R.; China
| | - Hua Wei
- State Key Laboratory of Food Science and Technology, Nanchang Univ.; 235 Nanjing; Donglu, Nanchang 330047, P.R.; China
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