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Xu L, Wu Y, Yang X, Pang X, Wu Y, Li X, Liu X, Zhao Y, Yu L, Wang P, Ye B, Jiang S, Ma J, Zhang X. The Fe-S cluster biosynthesis in Enterococcus faecium is essential for anaerobic growth and gastrointestinal colonization. Gut Microbes 2024; 16:2359665. [PMID: 38831611 DOI: 10.1080/19490976.2024.2359665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 05/21/2024] [Indexed: 06/05/2024] Open
Abstract
The facultative anaerobic Gram-positive bacterium Enterococcus faecium is a ubiquitous member of the human gut microbiota. However, it has gradually evolved into a pathogenic and multidrug resistant lineage that causes nosocomial infections. The establishment of high-level intestinal colonization by enterococci represents a critical step of infection. The majority of current research on Enterococcus has been conducted under aerobic conditions, while limited attention has been given to its physiological characteristics in anaerobic environments, which reflects its natural colonization niche in the gut. In this study, a high-density transposon mutant library containing 26,620 distinct insertion sites was constructed. Tn-seq analysis identified six genes that significantly contribute to growth under anaerobic conditions. Under anaerobic conditions, deletion of sufB (encoding Fe-S cluster assembly protein B) results in more extensive and significant impairments on carbohydrate metabolism compared to aerobic conditions. Consistently, the pathways involved in this utilization-restricted carbohydrates were mostly expressed at significantly lower levels in mutant compared to wild-type under anaerobic conditions. Moreover, deletion of sufB or pflA (encoding pyruvate formate lyase-activating protein A) led to failure of gastrointestinal colonization in mice. These findings contribute to our understanding of the mechanisms by which E. faecium maintains proliferation under anaerobic conditions and establishes colonization in the gut.
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Affiliation(s)
- Linan Xu
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Yajing Wu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Xiangpeng Yang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinxin Pang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yansha Wu
- Institute of Edible Fungi, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Xingshuai Li
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xiayu Liu
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou, China
| | - Yuzhong Zhao
- College of Agriculture and Forestry, Linyi University, Linyi, China
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Lumin Yu
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Peikun Wang
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Bin Ye
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Shijin Jiang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Junfei Ma
- College of Agriculture and Forestry, Linyi University, Linyi, China
| | - Xinglin Zhang
- College of Agriculture and Forestry, Linyi University, Linyi, China
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Chaguza C, Pöntinen AK, Top J, Arredondo-Alonso S, Freitas AR, Novais C, Torres C, Bentley SD, Peixe L, Coque TM, Willems RJL, Corander J. The population-level impact of Enterococcus faecalis genetics on intestinal colonization and extraintestinal infection. Microbiol Spectr 2023; 11:e0020123. [PMID: 37811975 PMCID: PMC10714801 DOI: 10.1128/spectrum.00201-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 08/29/2023] [Indexed: 10/10/2023] Open
Abstract
IMPORTANCE Enterococcus faecalis causes life-threatening invasive hospital- and community-associated infections that are usually associated with multidrug resistance globally. Although E. faecalis infections cause opportunistic infections typically associated with antibiotic use, immunocompromised immune status, and other factors, they also possess an arsenal of virulence factors crucial for their pathogenicity. Despite this, the relative contribution of these virulence factors and other genetic changes to the pathogenicity of E. faecalis strains remain poorly understood. Here, we investigated whether specific genomic changes in the genome of E. faecalis isolates influence its pathogenicity-infection of hospitalized and nonhospitalized individuals and the propensity to cause extraintestinal infection and intestinal colonization. Our findings indicate that E. faecalis genetics partially influence the infection of hospitalized and nonhospitalized individuals and the propensity to cause extraintestinal infection, possibly due to gut-to-bloodstream translocation, highlighting the potential substantial role of host and environmental factors, including gut microbiota, on the opportunistic pathogenic lifestyle of this bacterium.
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Affiliation(s)
- Chrispin Chaguza
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, Connecticut, USA
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Anna K. Pöntinen
- Department of Biostatistics, Faculty of Medicine, University of Oslo, Oslo, Norway
- Norwegian National Advisory Unit on Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
| | - Janetta Top
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Sergio Arredondo-Alonso
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
- Department of Biostatistics, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Ana R. Freitas
- UCIBIO-Applied Molecular Biosciences Unit, Laboratory of Microbiology, Department of Biological Sciences, REQUIMTE Faculty of Pharmacy, University of Porto, Porto, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, Porto, Portugal
- TOXRUN, Toxicology Research Unit, University Institute of Health Sciences, CESPU, CRL, Gandra, Portugal
| | - Carla Novais
- UCIBIO-Applied Molecular Biosciences Unit, Laboratory of Microbiology, Department of Biological Sciences, REQUIMTE Faculty of Pharmacy, University of Porto, Porto, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Carmen Torres
- Department of Food and Agriculture, Area of Biochemistry and Molecular Biology, University of La Rioja, Logroño, Spain
| | - Stephen D. Bentley
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
| | - Luisa Peixe
- UCIBIO-Applied Molecular Biosciences Unit, Laboratory of Microbiology, Department of Biological Sciences, REQUIMTE Faculty of Pharmacy, University of Porto, Porto, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Faculty of Pharmacy, University of Porto, Porto, Portugal
| | - Teresa M. Coque
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), Madrid, Spain
- CIBER in Infectious Diseases (CIBERINFEC), Madrid, Spain
| | - Rob J. L. Willems
- Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Jukka Corander
- Parasites and Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, United Kingdom
- Department of Biostatistics, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Mathematics and Statistics, Helsinki Institute of Information Technology, University of Helsinki, Helsinki, Finland
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3
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Archambaud C, Derré-Bobillot A, Lapaque N, Rigottier-Gois L, Serror P. Intestinal translocation of enterococci requires a threshold level of enterococcal overgrowth in the lumen. Sci Rep 2019; 9:8926. [PMID: 31222056 PMCID: PMC6586816 DOI: 10.1038/s41598-019-45441-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/06/2019] [Indexed: 12/31/2022] Open
Abstract
Enterococci are subdominant members of the human gastrointestinal microbiota. Enterococcus faecalis is generally harmless for healthy individuals, but it can cause a diverse range of infections in immunodeficient or elderly patients with severe underlying diseases. In this study, we analysed the levels of intestinal translocation of indigenous enterococci in C57BL/6, CF-1 and CX3CR1−/− mice upon clindamycin antibiotic-induced dysbiosis. We found that C57BL/6 was the most permissive model for enterococcal translocation and that initiation of E. faecalis translocation coincided with a threshold of enterococcal colonisation in the gut lumen, which once reached, triggered E. faecalis dissemination to deeper organs. We showed that the extent to which E. faecalis clinical strain VE14821 competed with indigenous enterococci differed between the C57BL/6 and CX3CR1−/− models. Finally, using a simplified gnotobiotic model, we observed E. faecalis crossing an intact intestinal tract using intestinal epithelial cells as one route to reach the lamina propria. Our study opens new perspectives for assessing the effect of various immunodeficiencies and for investigating mechanisms underlying enterococcal translocation.
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Affiliation(s)
- Cristel Archambaud
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy en Josas, France.
| | - Aurélie Derré-Bobillot
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy en Josas, France
| | - Nicolas Lapaque
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy en Josas, France
| | - Lionel Rigottier-Gois
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy en Josas, France
| | - Pascale Serror
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy en Josas, France.
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Ramos Y, Rocha J, Hael AL, van Gestel J, Vlamakis H, Cywes-Bentley C, Cubillos-Ruiz JR, Pier GB, Gilmore MS, Kolter R, Morales DK. PolyGlcNAc-containing exopolymers enable surface penetration by non-motile Enterococcus faecalis. PLoS Pathog 2019; 15:e1007571. [PMID: 30742693 PMCID: PMC6386517 DOI: 10.1371/journal.ppat.1007571] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Revised: 02/22/2019] [Accepted: 01/08/2019] [Indexed: 11/20/2022] Open
Abstract
Bacterial pathogens have evolved strategies that enable them to invade tissues and spread within the host. Enterococcus faecalis is a leading cause of local and disseminated multidrug-resistant hospital infections, but the molecular mechanisms used by this non-motile bacterium to penetrate surfaces and translocate through tissues remain largely unexplored. Here we present experimental evidence indicating that E. faecalis generates exopolysaccharides containing β-1,6-linked poly-N-acetylglucosamine (polyGlcNAc) as a mechanism to successfully penetrate semisolid surfaces and translocate through human epithelial cell monolayers. Genetic screening and molecular analyses of mutant strains identified glnA, rpiA and epaX as genes critically required for optimal E. faecalis penetration and translocation. Mechanistically, GlnA and RpiA cooperated to generate uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) that was utilized by EpaX to synthesize polyGlcNAc-containing polymers. Notably, exogenous supplementation with polymeric N-acetylglucosamine (PNAG) restored surface penetration by E. faecalis mutants devoid of EpaX. Our study uncovers an unexpected mechanism whereby the RpiA-GlnA-EpaX metabolic axis enables production of polyGlcNAc-containing polysaccharides that endow E. faecalis with the ability to penetrate surfaces. Hence, targeting carbohydrate metabolism or inhibiting biosynthesis of polyGlcNAc-containing exopolymers may represent a new strategy to more effectively confront enterococcal infections in the clinic. Enterococcus faecalis is a microbial inhabitant of the human gastrointestinal tract that can cause lethal infections. Typically classified as a non-motile bacterium, E. faecalis can readily migrate and translocate across epithelial barriers to invade distant organs. Nevertheless, the molecular pathways driving enterococcal invasive attributes remain poorly understood. In this study, we uncover that E. faecalis produces a polyGlcNAc-containing extracellular glycopolymer to efficiently migrate into semisolid surfaces and translocate through human epithelial cell monolayers. Our work provides evidence that non-motile bacterial pathogens can exploit endogenous carbohydrate metabolic pathways to penetrate surfaces. Thus, targeting glycopolymer biosynthetic programs might be useful to control infections by Gram-positive cocci in the clinic.
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Affiliation(s)
- Yusibeska Ramos
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
| | - Jorge Rocha
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Ana L. Hael
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Jordi van Gestel
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, Switzerland
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Hera Vlamakis
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Colette Cywes-Bentley
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Juan R. Cubillos-Ruiz
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
| | - Gerald B. Pier
- Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States of America
| | - Michael S. Gilmore
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
- Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| | - Roberto Kolter
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, United States of America
| | - Diana K. Morales
- Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY, United States of America
- * E-mail:
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5
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Zhang X, Top J, de Been M, Bierschenk D, Rogers M, Leendertse M, Bonten MJM, van der Poll T, Willems RJL, van Schaik W. Identification of a genetic determinant in clinical Enterococcus faecium strains that contributes to intestinal colonization during antibiotic treatment. J Infect Dis 2013; 207:1780-6. [PMID: 23447698 DOI: 10.1093/infdis/jit076] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Intestinal colonization by antibiotic-resistant Enterococcus faecium is the first step in a process that can lead to infections in hospitalized patients. By comparative genome analysis and subsequent polymerase chain reaction screening, we identified a locus that encodes a putative phosphotransferase system (PTS). The PTS locus was widespread in isolates from hospital outbreaks of infection (84.2%) and nonoutbreak clinical infections (66.0%) but absent from human commensal isolates. Deletion of pstD, which is predicted to encode the enzyme IID subunit of this PTS, significantly impaired the ability of E. faecium to colonize the murine intestinal tract during antibiotic treatment. This is the first description of a determinant that contributes to intestinal colonization in clinical E. faecium strains.
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Affiliation(s)
- Xinglin Zhang
- Department of Medical Microbiology, University Medical Center Utrecht, The Netherlands
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6
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Velkers FC, van de Graaf-Bloois L, Wagenaar JA, Westendorp ST, van Bergen MAP, Dwars RM, Landman WJM. Enterococcus hirae-associated endocarditis outbreaks in broiler flocks: clinical and pathological characteristics and molecular epidemiology. Vet Q 2012; 31:3-17. [PMID: 22029817 DOI: 10.1080/01652176.2011.570107] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Enterococcus hirae-associated endocarditis, characterized by a peak in mortality during the second week of the grow-out, and occasionally lameness, was diagnosed at Dutch broiler farms. OBJECTIVES Field cases were studied to increase knowledge on clinical and pathological characteristics, pathogenesis and epidemiology of these infections. ANIMALS AND METHODS In total, 1266 birds of 25 flocks from 12 farms were examined. Post-mortem examinations, bacteriology, histopathology, PCR and DNA fingerprinting was carried out. Six flocks were followed longitudinally (n = 1017 birds). RESULTS Average mortality was 4.1% for the entire grow-out, of which 36% was attributed to endocarditis. Fibrinous thromboendocarditis of the right atrioventricular (AV) valve was found in 24% of hearts, compared to 7% and 4% with lesions of left and both AV valves, respectively. Thrombotic lesions were found in 24% (n = 432) of lungs, but only in larger branches of the Arteria pulmonalis. Occasionally, thrombi were found in the Arteria ischiadica externa and in liver and brain vessels. Enterococcus was cultured from 54% (n = 176) of heart and in 75% (n = 28), 62% (n = 106) and 31% (n = 16) of liver, bone marrow and lung samples, respectively. Further identification, using the Rapid ID Strep 32 API system and a PCR targeting mur-2 and mur-2(ed) genes was carried out on a subset of Enterococcus positive isolates (n = 65): both techniques identified the isolates as Enterococcus hirae. Pulsed-field gel electrophoresis did not indicate evidence of clonality between farms and flocks. CONCLUSIONS The relevance of these findings for pathogenesis and epidemiology of E. hirae infections is discussed. CLINICAL IMPORTANCE. This study may facilitate diagnosis of field cases and may contribute to the design of further research and development of control measures.
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Affiliation(s)
- F C Velkers
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
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7
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Large-scale screening of a targeted Enterococcus faecalis mutant library identifies envelope fitness factors. PLoS One 2011; 6:e29023. [PMID: 22194979 PMCID: PMC3240637 DOI: 10.1371/journal.pone.0029023] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 11/18/2011] [Indexed: 11/25/2022] Open
Abstract
Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% Gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence.
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Gatt M, Reddy BS, MacFie J. Review article: bacterial translocation in the critically ill--evidence and methods of prevention. Aliment Pharmacol Ther 2007; 25:741-57. [PMID: 17373913 DOI: 10.1111/j.1365-2036.2006.03174.x] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Delayed sepsis, systemic inflammatory response syndrome (SIRS) and multiorgan failure remain major causes of morbidity and mortality on intensive care units. One factor thought to be important in the aetiology of SIRS is failure of the intestinal barrier resulting in bacterial translocation and subsequent sepsis. AIM This review summarizes the current knowledge about bacterial translocation and methods to prevent it. METHODS Relevant studies during 1966-2006 were identified from a literature search. Factors, which detrimentally affect intestinal barrier function, are discussed, as are methods that may attenuate bacterial translocation in the critically ill patient. RESULTS Methodological problems in confirming bacterial translocation have restricted investigations to patients undergoing laparotomy. There are only limited data available relating to specific interventions that might preserve intestinal barrier function or limit bacterial translocation in the intensive care setting. These can be categorized broadly into pre-epithelial, epithelial and post-epithelial interventions. CONCLUSIONS A better understanding of factors that influence translocation could result in the implementation of interventions which contribute to improved patient outcomes. Glutamine supplementation, targeted nutritional intervention, maintaining splanchnic flow, the judicious use of antibiotics and directed selective gut decontamination regimens hold some promise of limiting bacterial translocation. Further research is required.
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Affiliation(s)
- M Gatt
- Combined Gastroenterology Research Unit, Scarborough General Hospital, Woodlands Drive, Scarborough, UK
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9
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Chen LW, Huang HL, Lee IT, Hsu CM, Lu PJ. Hypertonic saline enhances host defense to bacterial challenge by augmenting Toll-like receptors*. Crit Care Med 2006; 34:1758-68. [PMID: 16625117 DOI: 10.1097/01.ccm.0000218810.66485.01] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To determine whether hypertonic saline infusion modulates thermal injury-induced bacterial translocation and host response to bacterial challenge through the augmentation of Toll-like receptors (TLRs). DESIGN Prospective, experimental study. SETTING Research laboratory at a university hospital. SUBJECTS Thermal injury models in the mice. INTERVENTIONS In experiment 1, mice underwent burn were given with 10 mL/kg hypertonic saline (7.5% NaCl), 10 mg/kg saline (N/S1), or 80 mL/kg saline (N/S2) at 4 or 8 hrs after burn. At 24 hrs after burn, mesenteric lymph nodes were harvested for bacterial translocation assay. In experiment 2, mice receiving hypertonic saline or saline after thermal injury received peritoneal challenge with Escherichia coli, and bacterial clearance was measured. In experiment 3, peritoneal cells from mice receiving hypertonic saline or saline after thermal injury were incubated with E. coli, and bacterial count, TLR2, TLR4, MIP2, CXCR2, pp38, and ERK expression were evaluated. In experiment 4, reactive oxygen species production, CXCR2, MIP2, TLR2, and TLR4 expression of bone marrow neutrophil from mice receiving hypertonic saline or saline treatment after thermal injury were evaluated. In experiment 5, neutrophil were cultured with hypertonic saline or N/S and incubated with E. coli. TLR2 and TLR4 expression and bacterial count were evaluated. In experiment 6, mice were fed with oral antibiotics with or without lipopolysaccharide, a TLR ligand, supplements. At 24 hrs after burn, mesenteric lymph nodes were harvested for bacterial translocation assay, and neutrophils were harvested for TLR2 and TLR4 protein assay. MEASUREMENTS AND MAIN RESULTS Hypertonic saline decreased thermal injury-induced bacterial translocation. Hypertonic saline increased bacterial clearance, phagocytic activity, and TLR2, TLR4, CXCR2, pp38, and p44/42 expression of peritoneal cells. Hypertonic saline treatment at 4 or 8 hrs after thermal injury decreased reactive oxygen species production of neutrophil. Hypertonic saline injection increased TLR2, TLR4, and pp38 expression of neutrophil. In vitro treatment of neutrophil with hypertonic saline increased phagocytic activity and TLR2 and TLR4 expression. Commensal depletion with oral antibiotics decreased TLR2 and TLR4 expression of neutrophil; lipopolysaccharide increased TLR4 expression of neutrophil and decreased thermal injury-induced bacterial translocation. CONCLUSIONS Restoration of extracellular fluid in burn shock with hypertonic saline decreased thermal injury-induced bacterial translocation. Hypertonic saline increased the phagocytic activity and TLR2, TLR4, CXCR2, pp38, and P44/42 expression of peritoneal cells. Hypertonic saline decreased reactive oxygen species but increased TLR2, TLR4, and pp38 expression and phagocytic activity of bone marrow neutrophil. Stimulation of the TLRs with lipopolysaccharide in commensal depleted mice increased TLRs expression of neutrophil and decreased thermal injury-induced bacterial translocation. Taken together with the fact that stimulation of TLRs with hypertonic saline increases phagocytic activity of systemic inflammatory cells, we conclude that TLRs play a critical role in the innate immunity by recognizing bacteria and that hypertonic saline enhances host response to bacterial challenge by increasing TLRs of inflammatory cells.
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Affiliation(s)
- Lee-Wei Chen
- Department of Surgery, Kaohsiung Veterans General Hospital, National Yang-Ming Medical University, Taipei (L-WC, I-TL), R.O.C
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10
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Koh AY, Priebe GP, Pier GB. Virulence of Pseudomonas aeruginosa in a murine model of gastrointestinal colonization and dissemination in neutropenia. Infect Immun 2005; 73:2262-72. [PMID: 15784570 PMCID: PMC1087461 DOI: 10.1128/iai.73.4.2262-2272.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa bacteremia in cancer patients develops from initial gastrointestinal (GI) colonization with translocation into the bloodstream in the setting of chemotherapy-induced neutropenia and GI mucosal damage. We established a reproducible mouse model of P. aeruginosa GI colonization and systemic spread during neutropenia. Mice received 2 mg of streptomycin/ml of drinking water and 1,500 U of penicillin G/ml for 4 days and then ingested 10(7) CFU of P. aeruginosa per ml of drinking water for 5 days. After GI colonization levels were determined, cyclophosphamide (Cy) was then injected intraperitoneally (i.p.) three times every other day or an antineutrophil monoclonal antibody, RB6-8C5, was injected i.p. once. Dissemination was defined by the presence of P. aeruginosa in spleens of moribund or dead mice. In this mouse model, P. aeruginosa colonizes the GI tract and then disseminates systemically once Cy or RB6-8C5 is administered. The duration and intensity of neutropenia, related to Cy dose, was found to be a means to compare the virulence of different P. aeruginosa strains, as exhibited by comparisons of strains lacking or producing the virulence-enhancing ExoU cytotoxin. The lipopolysaccharide outer core polysaccharide and O side chains were critical in establishing GI colonization, and P. aeruginosa mutants lacking the aroA gene (necessary for synthesizing aromatic amino acids) were able to establish GI colonization but unable to disseminate. Both the colonization and dissemination phases of P. aeruginosa pathogenesis can be studied in this model, which should prove useful for evaluating pathogenesis, therapies, and associated means to control P. aeruginosa nosocomial infections.
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Affiliation(s)
- Andrew Y Koh
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Ave., Boston, MA 02115, USA.
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11
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Zeng J, Teng F, Murray BE. Gelatinase is important for translocation of Enterococcus faecalis across polarized human enterocyte-like T84 cells. Infect Immun 2005; 73:1606-12. [PMID: 15731060 PMCID: PMC1064952 DOI: 10.1128/iai.73.3.1606-1612.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previously, in our laboratory, we established a two-chamber system to study translocation of Enterococcus faecalis across monolayers of polarized human colon carcinoma-derived T84 cells. By using the same system in the present study, we now show that disruption of gelE of strain OG1RF, which also has a polar effect on the cotranscribed sprE, as well as disruption of its regulatory system (fsrA, fsrB, and fsrC) resulted in a loss of detectable translocation by E. faecalis OG1RF; these mutants lost gelatinase (GelE) and serine protease (SprE) production by standard assay. A gelE deletion mutant of OG1RF (GelE- SprE+) also showed that significantly reduced translocation and complementation with the gelE gene (pTEX5438) in trans restored gelatinase and translocation, demonstrating that gelatinase is important for E. faecalis translocation. Complementation of fsrA, fsrB, and fsrC mutants with all three fsr genes also resulted in production of gelatinase and translocation. Furthermore, introduction of fsr genes into two non-gelatinase-producing E. faecalis isolates, the well-characterized laboratory strain JH2-2 and a human-derived fecal isolate, TX1322 (both of which have gelE but not fsrA or fsrB, are gelatinase negative, and do not translocate), resulted in gelatinase production by these strains and restored translocation across T84 monolayers, while transformation with pTEX5438 (gelE) showed little or no translocation and no detectable gelatinase, confirming the importance of both fsr and gelatinase for E. faecalis translocation. The importance of gelatinase production was also corroborated among 20 E. faecalis human isolates (7 fecal, 7 endocarditis, and 6 urine isolates), which showed translocation by all gelatinase-positive isolates but little to no translocation for gelatinase nonproducers. These results indicate that gelatinase is important for the successful in vitro translocation of E. faecalis across human enterocyte-like T84 cells.
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Affiliation(s)
- Jing Zeng
- Department of Internal Medicine, Division of Infectious Diseases, 1728 JFB, University of Texas Medical School, 6431 Fannin St., Houston, TX 77030, USA
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Koch S, Hufnagel M, Huebner J. Treatment and prevention of enterococcal infections--alternative and experimental approaches. Expert Opin Biol Ther 2005; 4:1519-31. [PMID: 15335318 DOI: 10.1517/14712598.4.9.1519] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Enterococci are one of the leading types of organisms isolated from infections of hospitalised patients and the third most common cause of nosocomial bloodstream infections. They contribute significantly to patient mortality and morbidity, as well as healthcare costs. The emergence of resistance against virtually all clinically available antibiotics and the ability to transfer these resistance determinants to other pathogens demonstrates the urgency for an improved understanding of enterococcal virulence mechanisms, and the development of alternative treatment and prevention options. This article reviews new antimicrobials, vaccine targets, bacteriophage therapy, as well as treatments targeting virulence factors and biofilm, for their potential to treat and/or prevent enterococcal infections. Although clinical isolates often cause serious infections, so-called 'non-pathogenic' strains are used as therapeutics in the form of probiotics. Understanding the differences between true pathogens and beneficial commensals may help to evaluate future treatment and prophylactic options.
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Affiliation(s)
- Stefanie Koch
- Department of Medicine, Channing Laboratory, Brigham and Women's Hospital, 181 Longwood Ave, Boston, MA 02115, USA
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Theilacker C, Krueger WA, Kropec A, Huebner J. Rationale for the development of immunotherapy regimens against enterococcal infections. Vaccine 2004; 22 Suppl 1:S31-8. [PMID: 15576199 DOI: 10.1016/j.vaccine.2004.08.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Enterococci are the third most common pathogen isolated in bloodstream infections. Increasing resistance against multiple antimicrobial agents has left few treatment options for enterococcal infections, and alternative therapeutic approaches are needed. Although a variety of virulence factors have been described for Enterococcus faecalis, only aggregation substance (AS) and a teichoic acid-like capsular polysaccharide have been evaluated for their potential for vaccine development. Antibodies raised against purified capsular polysaccharide are highly opsonic and protect mice against bacteremia after active and passive immunization. Since E. faecalis expresses only a limited number of capsular serotypes, this antigen may be an attractive candidate for development of a conjugate vaccine.
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Affiliation(s)
- Christian Theilacker
- Infectious Diseases, Department of Medicine, University Hospital Freiburg, Germany
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