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Wang S, Mirmiran SD, Li X, Li X, Zhang F, Duan X, Gao D, Chen Y, Chen H, Qian P. Temperate phage influence virulence and biofilm-forming of Salmonella Typhimurium and enhance the ability to contaminate food product. Int J Food Microbiol 2023; 398:110223. [PMID: 37120944 DOI: 10.1016/j.ijfoodmicro.2023.110223] [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: 12/25/2022] [Revised: 04/05/2023] [Accepted: 04/18/2023] [Indexed: 05/02/2023]
Abstract
Salmonella is a food-borne zoonotic pathogen that threatens food safety and public health security. Temperate phages can influence bacterial virulence and phenotype and play an important role in bacterial evolution. However, most studies on Salmonella temperate phages focus on prophage induced by bacteria, with few reports on Salmonella temperate phages isolated in the environment. Moreover, whether temperate phages drive bacterial virulence and biofilm formation in food and animal models remains unknown. In this study, Salmonella temperate phage vB_Sal_PHB48 was isolated from sewage. TEM and phylogenetic analysis indicated that phage PHB48 belongs to the Myoviridae family. Additionally, Salmonella Typhimurium integrating PHB48 was screened and designated as Sal013+. Whole genome sequencing revealed that the integration site was specific and we confirmed that the integration of PHB48 did not change the O-antigen and coding sequences of Sal013. Our in vitro and in vivo studies showed that the integration of PHB48 could significantly enhance the virulence and biofilm formation of S. Typhimurium. More importantly, the integration of PHB48 significantly improved the colonization and contamination ability of bacteria in food samples. In conclusion, we isolated Salmonella temperate phage directly from the environment and systematically clarified that PHB48 enhanced the virulence and biofilm-forming ability of Salmonella. In addition, we found that PHB48 increased the colonization and contamination ability of Salmonella in food samples. These results indicated that the highly pathogenic Salmonella induced by temperate phage was more harmful to food matrices and public health security. Our results could enhance the understanding of the evolutionary relationship between bacteriophages and bacteria, and raise public awareness of large-scale outbreaks resulting from Salmonella virulence enhancement in food industry.
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Affiliation(s)
- Shuang Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Seyyed Danial Mirmiran
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Xiangmin Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Xinxin Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Fenqiang Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Xiaochao Duan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Dongyang Gao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Yibao Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China
| | - Ping Qian
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, 430070 Wuhan, China; The Cooperative Innovation Centre for Sustainable Pig Production, Huazhong Agricultural University, 430070 Wuhan, China; College of Veterinary Medicine, Huazhong Agricultural University, 430070 Wuhan, China.
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2
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Nakkarach A, Foo HL, Song AAL, Mutalib NEA, Nitisinprasert S, Withayagiat U. Anti-cancer and anti-inflammatory effects elicited by short chain fatty acids produced by Escherichia coli isolated from healthy human gut microbiota. Microb Cell Fact 2021; 20:36. [PMID: 33546705 PMCID: PMC7863513 DOI: 10.1186/s12934-020-01477-z] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/19/2020] [Indexed: 01/01/2023] Open
Abstract
Background Extracellular metabolites of short chain fatty acids (SCFA) excreted by gut microbiota have been reported to play an important role in the regulation of intestinal homeostasis. Apart from supplying energy, SCFA also elicit immune stimulation in animal and human cells. Therefore, an attempt was conducted to isolate SCFA producing bacteria from healthy human microbiota. The anti-cancer and anti-inflammatory effects of extracellular metabolites and individual SFCA were further investigated by using breast, colon cancer and macrophage cells. Toxin, inflammatory and anti-inflammatory cytokine gene expressions were investigated by RT-qPCR analyses in this study. Results Escherichia coli KUB-36 was selected in this study since it has the capability to produce seven SCFA extracellularly. It produced acetic acid as the main SCFA. It is a non-exotoxin producer and hence, it is a safe gut microbiota. The IC50 values indicated that the E. coli KUB-36 metabolites treatment elicited more potent cytotoxicity effect on MCF7 breast cancer cell as compared to colon cancer and leukemia cancer cells but exhibited little cytotoxic effects on normal breast cell. Furthermore, E. coli KUB-36 metabolites and individual SCFA could affect inflammatory responses in lipopolysaccharide-induced THP-1 macrophage cells since they suppressed inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α well as compared to the control, whilst inducing anti-inflammatory cytokine IL-10 expression. Conclusion SCFA producing E. coli KUB-36 possessed vast potential as a beneficial gut microbe since it is a non-exotoxin producer that exhibited beneficial cytotoxic effects on cancer cells and elicited anti-inflammatory activity simultaneously. However, the probiotic characteristic of E. coli KUB-36 should be further elucidated using in vivo animal models.![]()
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Affiliation(s)
- Atchareeya Nakkarach
- Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.,Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Chatuchak, 10900, Bangkok, Thailand
| | - Hooi Ling Foo
- Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia. .,Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
| | - Adelene Ai-Lian Song
- Institute of Bioscience, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.,Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia
| | - Nur Elina Abdul Mutalib
- Agro-Biotechnology Institute, National Institutes of Biotechnology Malaysia, 43000 UPM, Serdang, Selangor, Malaysia
| | - Sunee Nitisinprasert
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Chatuchak, 10900, Bangkok, Thailand
| | - Ulaiwan Withayagiat
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, Chatuchak, 10900, Bangkok, Thailand. .,Fermentation Technology Research Center, Faculty of Agro‑Industry, Kasetsart University, Chatuchak, 10900, Bangkok, Thailand.
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3
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Desvaux M, Dalmasso G, Beyrouthy R, Barnich N, Delmas J, Bonnet R. Pathogenicity Factors of Genomic Islands in Intestinal and Extraintestinal Escherichia coli. Front Microbiol 2020; 11:2065. [PMID: 33101219 PMCID: PMC7545054 DOI: 10.3389/fmicb.2020.02065] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 08/05/2020] [Indexed: 12/20/2022] Open
Abstract
Escherichia coli is a versatile bacterial species that includes both harmless commensal strains and pathogenic strains found in the gastrointestinal tract in humans and warm-blooded animals. The growing amount of DNA sequence information generated in the era of "genomics" has helped to increase our understanding of the factors and mechanisms involved in the diversification of this bacterial species. The pathogenic side of E. coli that is afforded through horizontal transfers of genes encoding virulence factors enables this bacterium to become a highly diverse and adapted pathogen that is responsible for intestinal or extraintestinal diseases in humans and animals. Many of the accessory genes acquired by horizontal transfers form syntenic blocks and are recognized as genomic islands (GIs). These genomic regions contribute to the rapid evolution, diversification and adaptation of E. coli variants because they are frequently subject to rearrangements, excision and transfer, as well as to further acquisition of additional DNA. Here, we review a subgroup of GIs from E. coli termed pathogenicity islands (PAIs), a concept defined in the late 1980s by Jörg Hacker and colleagues in Werner Goebel's group at the University of Würzburg, Würzburg, Germany. As with other GIs, the PAIs comprise large genomic regions that differ from the rest of the genome by their G + C content, by their typical insertion within transfer RNA genes, and by their harboring of direct repeats (at their ends), integrase determinants, or other mobility loci. The hallmark of PAIs is their contribution to the emergence of virulent bacteria and to the development of intestinal and extraintestinal diseases. This review summarizes the current knowledge on the structure and functional features of PAIs, on PAI-encoded E. coli pathogenicity factors and on the role of PAIs in host-pathogen interactions.
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Affiliation(s)
- Mickaël Desvaux
- Université Clermont Auvergne, INRAE, MEDiS, Clermont-Ferrand, France
| | - Guillaume Dalmasso
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Racha Beyrouthy
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - Nicolas Barnich
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Julien Delmas
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - Richard Bonnet
- UMR Inserm 1071, USC-INRAE 2018, M2iSH, Université Clermont Auvergne, Clermont-Ferrand, France
- Laboratoire de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
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4
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Nakkarach A, Foo HL, Song AAL, Nitisinprasert S, Withayagiat U. Promising discovery of beneficial Escherichia coli in the human gut. 3 Biotech 2020; 10:296. [PMID: 32550113 DOI: 10.1007/s13205-020-02289-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 06/01/2020] [Indexed: 01/03/2023] Open
Abstract
Ingested dietary fibres are hydrolysed by colon microbiota to produce energy-providing short-chain fatty acids (SCFA) that stimulate anti-inflammatory effects. SCFA-producing bacteria were screened from bacteria isolated from human faeces using bromothymol blue as an acid indicator and gas chromatography for SCFA profiling. The beneficial functions (antagonistic activity, haemolytic activities, antibiotic susceptibility, mucus adherent percentage and toxin gene detection) were evaluated for the top five SCFA-producing bacteria isolated from three healthy volunteers that identified as Escherichia coli strains. They produced acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acids at average concentrations of 15.9, 1.8, 1.1, 1.9, 1.8, 2.7 and 3.4 mM, respectively. The SCFA production by E. coli strains was rapidly increased during the first 8 h of incubation and gradually decreased after 16 h of incubation. All E. coli strains showed acid and bile tolerance, resulting in a survival rate greater than 70% with no haemolytic activity, mucus adherence greater than 40% and susceptibility to conventional antibiotics. Hence, the selected E. coli strains exhibited promising probiotic properties with neither enterotoxin nor LPS producibility was detected. The present results confirm the existence of friendly and harmless E. coli strains in human microbiota as potential probiotics.
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Affiliation(s)
- Atchareeya Nakkarach
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Hooi Ling Foo
- Department of Bioprocess, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Adelene Ai-Lian Song
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Malaysia
| | - Sunee Nitisinprasert
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
| | - Ulaiwan Withayagiat
- Department of Biotechnology, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
- Fermentation Technology Research Center, Faculty of Agro-Industry, Kasetsart University, 50 Ngam Wong Wan Road, Lat Yao, Chatuchak, Bangkok, 10900 Thailand
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5
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Chatterjee R, Shreenivas MM, Sunil R, Chakravortty D. Enteropathogens: Tuning Their Gene Expression for Hassle-Free Survival. Front Microbiol 2019; 9:3303. [PMID: 30687282 PMCID: PMC6338047 DOI: 10.3389/fmicb.2018.03303] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/19/2018] [Indexed: 12/27/2022] Open
Abstract
Enteropathogenic bacteria have been the cause of the majority of foodborne illnesses. Much of the research has been focused on elucidating the mechanisms by which these pathogens evade the host immune system. One of the ways in which they achieve the successful establishment of a niche in the gut microenvironment and survive is by a chain of elegantly regulated gene expression patterns. Studies have shown that this process is very elaborate and is also regulated by several factors. Pathogens like, enteropathogenic Escherichia coli (EPEC), Salmonella Typhimurium, Shigellaflexneri, Yersinia sp. have been seen to employ various regulated gene expression strategies. These include toxin-antitoxin systems, quorum sensing systems, expression controlled by nucleoid-associated proteins (NAPs), several regulons and operons specific to these pathogens. In the following review, we have tried to discuss the common gene regulatory systems of enteropathogenic bacteria as well as pathogen-specific regulatory mechanisms.
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Affiliation(s)
- Ritika Chatterjee
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India.,Division of Biological Sciences, Indian Institute of Science, Bengaluru, India
| | - Meghanashree M Shreenivas
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India.,Division of Biological Sciences, Indian Institute of Science, Bengaluru, India.,Undergraduate Studies, Indian Institute of Science, Bengaluru, India
| | - Rohith Sunil
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India.,Division of Biological Sciences, Indian Institute of Science, Bengaluru, India.,Undergraduate Studies, Indian Institute of Science, Bengaluru, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India.,Division of Biological Sciences, Indian Institute of Science, Bengaluru, India.,Centre for Biosystems Science and Engineering, Indian Institute of Science, Bengaluru, India
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6
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Ali IH, Jabir MS, Al-Shmgani HSA, Sulaiman GM, Sadoon AH. Pathological And Immunological Study On Infection With Escherichia Coli In ale BALB/c mice. ACTA ACUST UNITED AC 2018. [DOI: 10.1088/1742-6596/1003/1/012009] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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7
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Kang E, Crouse A, Chevallier L, Pontier SM, Alzahrani A, Silué N, Campbell-Valois FX, Montagutelli X, Gruenheid S, Malo D. Enterobacteria and host resistance to infection. Mamm Genome 2018; 29:558-576. [PMID: 29785663 DOI: 10.1007/s00335-018-9749-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/14/2018] [Indexed: 02/06/2023]
Abstract
Enterobacteriaceae are a large family of Gram-negative, non-spore-forming bacteria. Although many species exist as part of the natural flora of animals including humans, some members are associated with both intestinal and extraintestinal diseases. In this review, we focus on members of this family that have important roles in human disease: Salmonella, Escherichia, Shigella, and Yersinia, providing a brief overview of the disease caused by these bacteria, highlighting the contribution of animal models to our understanding of their pathogenesis and of host genetic determinants involved in susceptibility or resistance to infection.
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Affiliation(s)
- Eugene Kang
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
- McGill Research Center on Complex Traits, McGill University, Montreal, QC, Canada
| | - Alanna Crouse
- McGill Research Center on Complex Traits, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Lucie Chevallier
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, École Nationale Vétérinaire d'Alfort, UPEC, Maisons-Alfort, France
- Mouse Genetics Laboratory, Department of Genomes and Genetics, Institut Pasteur, Paris, France
| | - Stéphanie M Pontier
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - Ashwag Alzahrani
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - Navoun Silué
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
| | - François-Xavier Campbell-Valois
- Department of Chemistry and Biomolecular Sciences, Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Xavier Montagutelli
- U955 - IMRB, Team 10 - Biology of the neuromuscular system, Inserm, École Nationale Vétérinaire d'Alfort, UPEC, Maisons-Alfort, France
| | - Samantha Gruenheid
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
- McGill Research Center on Complex Traits, McGill University, Montreal, QC, Canada
| | - Danielle Malo
- McGill Research Center on Complex Traits, McGill University, Montreal, QC, Canada.
- Department of Human Genetics, McGill University, Montreal, QC, Canada.
- Department of Medicine, McGill University, Montreal, QC, Canada.
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8
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Vila J, Sáez-López E, Johnson JR, Römling U, Dobrindt U, Cantón R, Giske CG, Naas T, Carattoli A, Martínez-Medina M, Bosch J, Retamar P, Rodríguez-Baño J, Baquero F, Soto SM. Escherichia coli: an old friend with new tidings. FEMS Microbiol Rev 2018; 40:437-463. [PMID: 28201713 DOI: 10.1093/femsre/fuw005] [Citation(s) in RCA: 180] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 09/23/2015] [Accepted: 02/04/2016] [Indexed: 12/16/2022] Open
Abstract
Escherichia coli is one of the most-studied microorganisms worldwide but its characteristics are continually changing. Extraintestinal E. coli infections, such as urinary tract infections and neonatal sepsis, represent a huge public health problem. They are caused mainly by specialized extraintestinal pathogenic E. coli (ExPEC) strains that can innocuously colonize human hosts but can also cause disease upon entering a normally sterile body site. The virulence capability of such strains is determined by a combination of distinctive accessory traits, called virulence factors, in conjunction with their distinctive phylogenetic background. It is conceivable that by developing interventions against the most successful ExPEC lineages or their key virulence/colonization factors the associated burden of disease and health care costs could foreseeably be reduced in the future. On the other hand, one important problem worldwide is the increase of antimicrobial resistance shown by bacteria. As underscored in the last WHO global report, within a wide range of infectious agents including E. coli, antimicrobial resistance has reached an extremely worrisome situation that ‘threatens the achievements of modern medicine’. In the present review, an update of the knowledge about the pathogenicity, antimicrobial resistance and clinical aspects of this ‘old friend’ was presented.
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Affiliation(s)
- J Vila
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
- Department of Clinical Microbiology, Hospital Clinic, Universitat de Barcelona, Barcelona, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Instituto de Salud Carlos III, Madrid, Spain
| | - E Sáez-López
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - J R Johnson
- VA Medical Center, Minneapolis, MN, USA, and University of Minnesota, Minneapolis, MN, USA
| | - U Römling
- Karolinska Institute, Stockholm, Sweden
| | - U Dobrindt
- Institute of Hygiene, University of Münster, Münster, Germany
| | - R Cantón
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal and Instituto de Investigación Sanitaria (IRYCIS), Madrid, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Instituto de Salud Carlos III, Madrid, Spain
| | - C G Giske
- Karolinska Institute, Stockholm, Sweden
| | - T Naas
- Hôpital de Bicêtre, Université Paris Sud, Le Kremlin-Bicêtre, France
| | - A Carattoli
- Department of infectious, parasitic and immune-mediated diseases, Istituto Superiore di Sanità, Rome, Italy
| | - M Martínez-Medina
- Laboratory of Molecular Microbiology, Department of Biology, University of Girona, Girona, Spain
| | - J Bosch
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
- Department of Clinical Microbiology, Hospital Clinic, Universitat de Barcelona, Barcelona, Spain
| | - P Retamar
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Departamento de Medicina, Universidad de Sevilla, Seville, Spain
| | - J Rodríguez-Baño
- Unidad Clínica de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospitales Universitarios Virgen Macarena y Virgen del Rocío, Departamento de Medicina, Universidad de Sevilla, Seville, Spain
- Spanish Network for Research in Infectious Diseases (REIPI), Instituto de Salud Carlos III, Madrid, Spain
| | - F Baquero
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal and Instituto de Investigación Sanitaria (IRYCIS), Madrid, Spain
| | - S M Soto
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
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9
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Wang H, Wang J, Yu P, Ge P, Jiang Y, Xu R, Chen R, Liu X. Identification of antibiotic resistance genes in the multidrug-resistant Acinetobacter baumannii strain, MDR-SHH02, using whole-genome sequencing. Int J Mol Med 2016; 39:364-372. [PMID: 28035408 PMCID: PMC5358717 DOI: 10.3892/ijmm.2016.2844] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 12/07/2016] [Indexed: 01/28/2023] Open
Abstract
This study aimed to investigate antibiotic resistance genes in the multidrug-resistant (MDR) Acinetobacter baumannii (A. baumanii) strain, MDR-SHH02, using whole-genome sequencing (WGS). The antibiotic resistance of MDR-SHH02 isolated from a patient with breast cancer to 19 types of antibiotics was determined using the Kirby-Bauer method. WGS of MDR-SHH02 was then performed. Following quality control and transcriptome assembly, functional annotation of genes was conducted, and the phylogenetic tree of MDR-SHH02, along with another 5 A. baumanii species and 2 Acinetobacter species, was constructed using PHYLIP 3.695 and FigTree v1.4.2. Furthermore, pathogenicity islands (PAIs) were predicted by the pathogenicity island database. Potential antibiotic resistance genes in MDR-SHH02 were predicted based on the information in the Antibiotic Resistance Genes Database (ARDB). MDR-SHH02 was found to be resistant to all of the tested antibiotics. The total draft genome length of MDR-SHH02 was 4,003,808 bp. There were 74.25% of coding sequences to be annotated into 21 of the Clusters of Orthologous Groups (COGs) of protein terms, such as 'transcription' and 'amino acid transport and metabolism'. Furthermore, there were 45 PAIs homologous to the sequence MDRSHH02000806. Additionally, a total of 12 gene sequences in MDR-SHH02 were highly similar to the sequences of antibiotic resistance genes in ARDB, including genes encoding aminoglycoside-modifying enzymes [e.g., aac(3)-Ia, ant(2″)-Ia, aph33ib and aph(3′)-Ia], β-lactamase genes (bl2b_tem and bl2b_tem1), sulfonamide-resistant dihydropteroate synthase genes (sul1 and sul2), catb3 and tetb. These results suggest that numerous genes mediate resistance to various antibiotics in MDR-SHH02, and provide a clinical guidance for the personalized therapy of A. baumannii-infected patients.
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Affiliation(s)
- Hualiang Wang
- Department of Molecular Biology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Jinghua Wang
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Peijuan Yu
- Department of Clinical Laboratory, The Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R. China
| | - Ping Ge
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Yanqun Jiang
- Department of Clinical Laboratory, The Sixth People's Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200233, P.R. China
| | - Rong Xu
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Rong Chen
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
| | - Xuejie Liu
- Department of Microbiology Laboratory, Shanghai Centre for Clinical Laboratory, Shanghai 200126, P.R. China
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10
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The Locus of Enterocyte Effacement and Associated Virulence Factors of Enterohemorrhagic Escherichia coli. Microbiol Spectr 2016; 2:EHEC-0007-2013. [PMID: 26104209 DOI: 10.1128/microbiolspec.ehec-0007-2013] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subset of Shiga toxin-producing Escherichia coli strains, termed enterohemorrhagic E. coli (EHEC), is defined in part by the ability to produce attaching and effacing (A/E) lesions on intestinal epithelia. Such lesions are characterized by intimate bacterial attachment to the apical surface of enterocytes, cytoskeletal rearrangements beneath adherent bacteria, and destruction of proximal microvilli. A/E lesion formation requires the locus of enterocyte effacement (LEE), which encodes a Type III secretion system that injects bacterial proteins into host cells. The translocated proteins, termed effectors, subvert a plethora of cellular pathways to the benefit of the pathogen, for example, by recruiting cytoskeletal proteins, disrupting epithelial barrier integrity, and interfering with the induction of inflammation, phagocytosis, and apoptosis. The LEE and selected effectors play pivotal roles in intestinal persistence and virulence of EHEC, and it is becoming clear that effectors may act in redundant, synergistic, and antagonistic ways during infection. Vaccines that target the function of the Type III secretion system limit colonization of reservoir hosts by EHEC and may thus aid control of zoonotic infections. Here we review the features and functions of the LEE-encoded Type III secretion system and associated effectors of E. coli O157:H7 and other Shiga toxin-producing E. coli strains.
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Genomic diversity of EPEC associated with clinical presentations of differing severity. Nat Microbiol 2016; 1:15014. [PMID: 27571975 DOI: 10.1038/nmicrobiol.2015.14] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 11/06/2015] [Indexed: 01/01/2023]
Abstract
Enteropathogenic Escherichia coli (EPEC) are diarrhoeagenic E. coli, and are a significant cause of gastrointestinal illness among young children in developing countries. Typical EPEC are identified by the presence of the bundle-forming pilus encoded by a virulence plasmid, which has been linked to an increased severity of illness, while atypical EPEC lack this feature. Comparative genomics of 70 total EPEC from lethal (LI), non-lethal symptomatic (NSI) or asymptomatic (AI) cases of diarrhoeal illness in children enrolled in the Global Enteric Multicenter Study was used to investigate the genomic differences in EPEC isolates obtained from individuals with various clinical outcomes. A comparison of the genomes of isolates from different clinical outcomes identified genes that were significantly more prevalent in EPEC isolates of symptomatic and lethal outcomes than in EPEC isolates of asymptomatic outcomes. These EPEC isolates exhibited previously unappreciated phylogenomic diversity and combinations of virulence factors. These comparative results highlight the diversity of the pathogen, as well as the complexity of the EPEC virulence factor repertoire.
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Molecular analysis of asymptomatic bacteriuria Escherichia coli strain VR50 reveals adaptation to the urinary tract by gene acquisition. Infect Immun 2015; 83:1749-64. [PMID: 25667270 DOI: 10.1128/iai.02810-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/09/2015] [Indexed: 12/21/2022] Open
Abstract
Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli responsible for >80% of all cases. One extreme of UTI is asymptomatic bacteriuria (ABU), which occurs as an asymptomatic carrier state that resembles commensalism. To understand the evolution and molecular mechanisms that underpin ABU, the genome of the ABU E. coli strain VR50 was sequenced. Analysis of the complete genome indicated that it most resembles E. coli K-12, with the addition of a 94-kb genomic island (GI-VR50-pheV), eight prophages, and multiple plasmids. GI-VR50-pheV has a mosaic structure and contains genes encoding a number of UTI-associated virulence factors, namely, Afa (afimbrial adhesin), two autotransporter proteins (Ag43 and Sat), and aerobactin. We demonstrated that the presence of this island in VR50 confers its ability to colonize the murine bladder, as a VR50 mutant with GI-VR50-pheV deleted was attenuated in a mouse model of UTI in vivo. We established that Afa is the island-encoded factor responsible for this phenotype using two independent deletion (Afa operon and AfaE adhesin) mutants. E. coli VR50afa and VR50afaE displayed significantly decreased ability to adhere to human bladder epithelial cells. In the mouse model of UTI, VR50afa and VR50afaE displayed reduced bladder colonization compared to wild-type VR50, similar to the colonization level of the GI-VR50-pheV mutant. Our study suggests that E. coli VR50 is a commensal-like strain that has acquired fitness factors that facilitate colonization of the human bladder.
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Abstract
Adhesins are a group of proteins in enterohemorrhagic Escherichia coli (EHEC) that are involved in the attachment or colonization of this pathogen to abiotic (plastic or steel) and biological surfaces, such as those found in bovine and human intestines. This review provides the most up-to-date information on these essential adhesion factors, summarizing important historical discoveries and analyzing the current and future state of this research. In doing so, the proteins intimin and Tir are discussed in depth, especially regarding their role in the development of attaching and effacing lesions and in EHEC virulence. Further, a series of fimbrial proteins (Lpf1, Lpf2, curli, ECP, F9, ELF, Sfp, HCP, and type 1 fimbriae) are also described, emphasizing their various contributions to adherence and colonization of different surfaces and their potential use as genetic markers in detection and classification of different EHEC serotypes. This review also discusses the role of several autotransporter proteins (EhaA-D, EspP, Saa and Sab, and Cah), as well as other proteins associated with adherence, such as flagella, EibG, Iha, and OmpA. While these proteins have all been studied to varying degrees, all of the adhesins summarized in this chapter have been linked to different stages of the EHEC life cycle, making them good targets for the development of more effective diagnostics and therapeutics.
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Affiliation(s)
- Brian D. McWilliams
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, 77555. USA
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Pathogenesis of human enterovirulent bacteria: lessons from cultured, fully differentiated human colon cancer cell lines. Microbiol Mol Biol Rev 2014; 77:380-439. [PMID: 24006470 DOI: 10.1128/mmbr.00064-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hosts are protected from attack by potentially harmful enteric microorganisms, viruses, and parasites by the polarized fully differentiated epithelial cells that make up the epithelium, providing a physical and functional barrier. Enterovirulent bacteria interact with the epithelial polarized cells lining the intestinal barrier, and some invade the cells. A better understanding of the cross talk between enterovirulent bacteria and the polarized intestinal cells has resulted in the identification of essential enterovirulent bacterial structures and virulence gene products playing pivotal roles in pathogenesis. Cultured animal cell lines and cultured human nonintestinal, undifferentiated epithelial cells have been extensively used for understanding the mechanisms by which some human enterovirulent bacteria induce intestinal disorders. Human colon carcinoma cell lines which are able to express in culture the functional and structural characteristics of mature enterocytes and goblet cells have been established, mimicking structurally and functionally an intestinal epithelial barrier. Moreover, Caco-2-derived M-like cells have been established, mimicking the bacterial capture property of M cells of Peyer's patches. This review intends to analyze the cellular and molecular mechanisms of pathogenesis of human enterovirulent bacteria observed in infected cultured human colon carcinoma enterocyte-like HT-29 subpopulations, enterocyte-like Caco-2 and clone cells, the colonic T84 cell line, HT-29 mucus-secreting cell subpopulations, and Caco-2-derived M-like cells, including cell association, cell entry, intracellular lifestyle, structural lesions at the brush border, functional lesions in enterocytes and goblet cells, functional and structural lesions at the junctional domain, and host cellular defense responses.
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Srikhanta YN, Hocking DM, Wakefield MJ, Higginson E, Robins-Browne RM, Yang J, Tauschek M. Control of bacterial virulence by the RalR regulator of the rabbit-specific enteropathogenic Escherichia coli strain E22. Infect Immun 2013; 81:4232-43. [PMID: 24002063 PMCID: PMC3811808 DOI: 10.1128/iai.00710-13] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/24/2013] [Indexed: 11/20/2022] Open
Abstract
Atypical enteropathogenic Escherichia coli (aEPEC) causes endemic diarrhea, diarrheal outbreaks, and persistent diarrhea in humans, but the mechanism by which aEPEC causes disease is incompletely understood. Virulence regulators and their associated regulons, which often include adhesins, play key roles in the expression of virulence factors in enteric pathogenic bacteria. In this study we identified a transcriptional regulator, RalR, in the rabbit-specific aEPEC strain, E22 (O103:H2) and examined its involvement in the regulation of virulence. Microarray analysis and quantitative real-time reverse transcription-PCR demonstrated that RalR enhances the expression of a number of genes encoding virulence-associated factors, including the Ral fimbria, the Aap dispersin, and its associated transport system, and downregulates several housekeeping genes, including fliC. These observations were confirmed by proteomic analysis of secreted and heat-extracted surface-associated proteins and by adherence and motility assays. To investigate the mechanism of RalR-mediated activation, we focused on its most highly upregulated target operons, ralCDEFGHI and aap. By using primer extension, electrophoretic mobility shift assay, and mutational analysis, we identified the promoter and operator sequences for these two operons. By employing promoter-lacZ reporter systems, we demonstrated that RalR activates the expression of its target genes by binding to one or more 8-bp palindromic sequences (with the consensus of TGTGCACA) located immediately upstream of the promoter core regions. Importantly, we also demonstrated that RalR is essential for virulence since infection of rabbits with E22 carrying a knockout mutation in the ralR gene completely abolished its ability to cause disease.
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Affiliation(s)
- Yogitha N. Srikhanta
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Dianna M. Hocking
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Matthew J. Wakefield
- Bioinformatics Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Genetics, The University of Melbourne, Victoria, Australia
| | - Ellen Higginson
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Roy M. Robins-Browne
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Ji Yang
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
| | - Marija Tauschek
- Department of Microbiology and Immunology, The University of Melbourne, Victoria, Australia
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Law RJ, Gur-Arie L, Rosenshine I, Finlay BB. In vitro and in vivo model systems for studying enteropathogenic Escherichia coli infections. Cold Spring Harb Perspect Med 2013; 3:a009977. [PMID: 23457294 DOI: 10.1101/cshperspect.a009977] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) belong to a group of bacteria known as attaching and effacing (A/E) pathogens that cause disease by adhering to the lumenal surfaces of their host's intestinal epithelium. EPEC and EHEC are major causes of infectious diarrhea that result in significant childhood morbidity and mortality worldwide. Recent advances in in vitro and in vivo modeling of these pathogens have contributed to our knowledge of how EPEC and EHEC attach to host cells and subvert host-cell signaling pathways to promote infection and cause disease. A more detailed understanding of how these pathogenic microbes infect their hosts and how the host responds to infection could ultimately lead to new therapeutic strategies to help control these significant enteric pathogens.
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Affiliation(s)
- Robyn J Law
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Phylogenetic and molecular analysis of food-borne shiga toxin-producing Escherichia coli. Appl Environ Microbiol 2013; 79:2731-40. [PMID: 23417002 DOI: 10.1128/aem.03552-12] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Seventy-five food-associated Shiga toxin-producing Escherichia coli (STEC) strains were analyzed by molecular and phylogenetic methods to describe their pathogenic potential. The presence of the locus of proteolysis activity (LPA), the chromosomal pathogenicity island (PAI) PAI ICL3, and the autotransporter-encoding gene sabA was examined by PCR. Furthermore, the occupation of the chromosomal integration sites of the locus of enterocyte effacement (LEE), selC, pheU, and pheV, as well as the Stx phage integration sites yehV, yecE, wrbA, z2577, and ssrA, was analyzed. Moreover, the antibiotic resistance phenotypes of all STEC strains were determined. Multilocus sequence typing (MLST) was performed, and sequence types (STs) and sequence type complexes (STCs) were compared with those of 42 hemolytic-uremic syndrome (HUS)-associated enterohemorrhagic E. coli (HUSEC) strains. Besides 59 STs and 4 STCs, three larger clusters were defined in this strain collection. Clusters A and C consist mostly of highly pathogenic eae-positive HUSEC strains and some related food-borne STEC strains. A member of a new O26 HUS-associated clone and the 2011 outbreak strain E. coli O104:H4 were found in cluster A. Cluster B comprises only eae-negative food-borne STEC strains as well as mainly eae-negative HUSEC strains. Although food-borne strains of cluster B were not clearly associated with disease, serotypes of important pathogens, such as O91:H21 and O113:H21, were in this cluster and closely related to the food-borne strains. Clonal analysis demonstrated eight closely related genetic groups of food-borne STEC and HUSEC strains that shared the same ST and were similar in their virulence gene composition. These groups should be considered with respect to their potential for human infection.
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RegR virulence regulon of rabbit-specific enteropathogenic Escherichia coli strain E22. Infect Immun 2013; 81:1078-89. [PMID: 23340312 DOI: 10.1128/iai.01325-12] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AraC-like regulators play a key role in the expression of virulence factors in enteric pathogens, such as enteropathogenic Escherichia coli (EPEC), enterotoxigenic E. coli, enteroaggregative E. coli, and Citrobacter rodentium. Bioinformatic analysis of the genome of rabbit-specific EPEC (REPEC) strain E22 (O103:H2) revealed the presence of a gene encoding an AraC-like regulatory protein, RegR, which shares 71% identity to the global virulence regulator, RegA, of C. rodentium. Microarray analysis demonstrated that RegR exerts 25- to 400-fold activation on transcription of several genes encoding putative virulence-associated factors, including a fimbrial operon (SEF14), a serine protease, and an autotransporter adhesin. These observations were confirmed by proteomic analysis of secreted and heat-extracted surface-associated proteins. The mechanism of RegR-mediated activation was investigated by using its most highly upregulated gene target, sefA. Transcriptional analyses and electrophoretic mobility shift assays showed that RegR activates the expression of sefA by binding to a region upstream of the sefA promoter, thereby relieving gene silencing by the global regulatory protein H-NS. Moreover, RegR was found to contribute significantly to virulence in a rabbit infection experiment. Taken together, our findings indicate that RegR controls the expression of a series of accessory adhesins that significantly enhance the virulence of REPEC strain E22.
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Martínez-Castillo A, Allué-Guardia A, Dahbi G, Blanco J, Creuzburg K, Schmidt H, Muniesa M. Type III effector genes and other virulence factors of Shiga toxin-encoding Escherichia coli isolated from wastewater. ENVIRONMENTAL MICROBIOLOGY REPORTS 2012; 4:147-155. [PMID: 23757242 DOI: 10.1111/j.1758-2229.2011.00317.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Pathogenic Shiga toxin-producing Escherichia coli (STEC) strains share the genes encoding Shiga toxins (stx) and many other virulence factors. The classification and evolutionary studies of pathogenic E. coli based on their virulence genes have been conducted with E. coli isolated from human and animal infections or outbreaks. In this study, we used 103 STEC strains isolated from faecally polluted water environments to analyse 23 virulence genes (stx1 , cdt, hlyA, saa, eae, three type III effector genes encoded within the locus of enterocyte effacement (LEE) and 15 non-LEE-encoded type III effector genes). Despite the presence of several stx2 variants, our isolates demonstrated low prevalence of the virulence genes (only 46.6% of the strains were positive for virulence determinants). Among these, the largest repertoire was found in a few O157:H7 isolates (most from cattle wastewater and one from sewage), while other serotypes showed fewer virulence determinants. The occurrence of most virulence genes seemed to be independent from one another. This was clear for hlyA (the most prevalent), cdt and cif (the least prevalent). Other effector genes, could be found or not in combination with others, suggesting that they can be mobilized independently. Our data suggest that E. coli strains can evolve separately by independently acquiring mobile genetic elements.
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Affiliation(s)
- Alexandre Martínez-Castillo
- Department of Microbiology, University of Barcelona, Diagonal 643, Annex, Floor 0, 08028 Barcelona, Spain. Laboratorio de Referencia de E. coli (LREC), Department of Microbiology and Parasitology, Faculty of Veterinary Science, University of Santiago de Compostela, 27002 Lugo, Spain. Institute of Food Science and Biotechnology, Department of Food Microbiology, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany
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Schneider G, Dobrindt U, Middendorf B, Hochhut B, Szijártó V, Emody L, Hacker J. Mobilisation and remobilisation of a large archetypal pathogenicity island of uropathogenic Escherichia coli in vitro support the role of conjugation for horizontal transfer of genomic islands. BMC Microbiol 2011; 11:210. [PMID: 21943043 PMCID: PMC3202238 DOI: 10.1186/1471-2180-11-210] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Accepted: 09/24/2011] [Indexed: 12/14/2022] Open
Abstract
Background A substantial amount of data has been accumulated supporting the important role of genomic islands (GEIs) - including pathogenicity islands (PAIs) - in bacterial genome plasticity and the evolution of bacterial pathogens. Their instability and the high level sequence similarity of different (partial) islands suggest an exchange of PAIs between strains of the same or even different bacterial species by horizontal gene transfer (HGT). Transfer events of archetypal large genomic islands of enterobacteria which often lack genes required for mobilisation or transfer have been rarely investigated so far. Results To study mobilisation of such large genomic regions in prototypic uropathogenic E. coli (UPEC) strain 536, PAI II536 was supplemented with the mobRP4 region, an origin of replication (oriVR6K), an origin of transfer (oriTRP4) and a chloramphenicol resistance selection marker. In the presence of helper plasmid RP4, conjugative transfer of the 107-kb PAI II536 construct occured from strain 536 into an E. coli K-12 recipient. In transconjugants, PAI II536 existed either as a cytoplasmic circular intermediate (CI) or integrated site-specifically into the recipient's chromosome at the leuX tRNA gene. This locus is the chromosomal integration site of PAI II536 in UPEC strain 536. From the E. coli K-12 recipient, the chromosomal PAI II536 construct as well as the CIs could be successfully remobilised and inserted into leuX in a PAI II536 deletion mutant of E. coli 536. Conclusions Our results corroborate that mobilisation and conjugal transfer may contribute to evolution of bacterial pathogens through horizontal transfer of large chromosomal regions such as PAIs. Stabilisation of these mobile genetic elements in the bacterial chromosome result from selective loss of mobilisation and transfer functions of genomic islands.
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Affiliation(s)
- György Schneider
- Institute for Molecular Infection Biology, University of Würzburg, Josef-Schneider-Str, 2/Building D15, Würzburg, 97070, Germany
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Sims GE, Kim SH. Whole-genome phylogeny of Escherichia coli/Shigella group by feature frequency profiles (FFPs). Proc Natl Acad Sci U S A 2011; 108:8329-34. [PMID: 21536867 PMCID: PMC3100984 DOI: 10.1073/pnas.1105168108] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A whole-genome phylogeny of the Escherichia coli/Shigella group was constructed by using the feature frequency profile (FFP) method. This alignment-free approach uses the frequencies of l-mer features of whole genomes to infer phylogenic distances. We present two phylogenies that accentuate different aspects of E. coli/Shigella genomic evolution: (i) one based on the compositions of all possible features of length l = 24 (∼8.4 million features), which are likely to reveal the phenetic grouping and relationship among the organisms and (ii) the other based on the compositions of core features with low frequency and low variability (∼0.56 million features), which account for ∼69% of all commonly shared features among 38 taxa examined and are likely to have genome-wide lineal evolutionary signal. Shigella appears as a single clade when all possible features are used without filtering of noncore features. However, results using core features show that Shigella consists of at least two distantly related subclades, implying that the subclades evolved into a single clade because of a high degree of convergence influenced by mobile genetic elements and niche adaptation. In both FFP trees, the basal group of the E. coli/Shigella phylogeny is the B2 phylogroup, which contains primarily uropathogenic strains, suggesting that the E. coli/Shigella ancestor was likely a facultative or opportunistic pathogen. The extant commensal strains diverged relatively late and appear to be the result of reductive evolution of genomes. We also identify clade distinguishing features and their associated genomic regions within each phylogroup. Such features may provide useful information for understanding evolution of the groups and for quick diagnostic identification of each phylogroup.
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Affiliation(s)
- Gregory E. Sims
- Department of Informatics, J. Craig Venter Institute, Rockville, MD 20850
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Sung-Hou Kim
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley CA 94720-1460; and
- Department of Integrated OMICS for Biomedical Sciences, Graduate School, Yonsei University, Seoul 120-749, Republic of Korea
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Bielaszewska M, Middendorf B, Tarr PI, Zhang W, Prager R, Aldick T, Dobrindt U, Karch H, Mellmann A. Chromosomal instability in enterohaemorrhagic Escherichia coli O157:H7: impact on adherence, tellurite resistance and colony phenotype. Mol Microbiol 2011; 79:1024-44. [PMID: 21299654 PMCID: PMC3064760 DOI: 10.1111/j.1365-2958.2010.07499.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tellurite (Tel) resistant enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is a global pathogen. In strain EDL933 Tel resistance (TelR) is encoded by duplicate ter cluster in O islands (OI) 43 and 48, which also harbour iha, encoding the adhesin and siderophore receptor Iha. We identified five EHEC O157:H7 strains that differentiate into large (L) colonies and small (S) colonies with high and low Tel minimal inhibitory concentrations (MICs) respectively. S colonies (Tel-MICs ≤ 4 µg ml−1) sustained large internal deletions within the TelR OIs via homologous recombination between IS elements and lost ter and iha. Moreover, complete excision of the islands occurred by site-specific recombination between flanking direct repeats. Complete excision of OI 43 and OI 48 occurred in 1.81 × 10−3 and 1.97 × 10−4 cells in culture, respectively; internal deletion of OI 48 was more frequent (9.7 × 10−1 cells). Under iron limitation that promotes iha transcription, iha-negative derivatives adhered less well to human intestinal epithelial cells and grew slower than did their iha-positive counterparts. Experiments utilizing iha deletion and complementation mutants identified Iha as the major factor responsible for these phenotypic differences. Spontaneous deletions affecting TelR OIs contribute to EHEC O157 genome plasticity and might impair virulence and/or fitness.
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Affiliation(s)
- Martina Bielaszewska
- Institute of Hygiene and the National Consulting Laboratory on Haemolytic Uraemic Syndrome, University of Münster, Robert Koch Str. 41, 48149 Münster, Germany.
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Creuzburg K, Middendorf B, Mellmann A, Martaler T, Holz C, Fruth A, Karch H, Schmidt H. Evolutionary analysis and distribution of type III effector genes in pathogenic Escherichia coli from human, animal and food sources. Environ Microbiol 2010; 13:439-52. [PMID: 20880329 DOI: 10.1111/j.1462-2920.2010.02349.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Molecular analysis of Shiga toxin-producing Escherichia coli (STEC) from different sources is considered as a major approach to assess their risk potential. However, only limited data are available about the correlation of evolutionary relationship, the presence of major virulence factor genes and the putative risk of an STEC strain for human infection. In this study, we analysed the evolutionary relationship of 136 pathogenic E. coli strains from human, animal and food sources by multi-locus sequence typing (MLST) and molecular subtyping of their Shiga toxin (stx) and intimin (eae) genes. Moreover, the distribution of three type III effector genes, encoded within the locus of enterocyte effacement (LEE), and 16 effector genes, which are encoded outside the LEE, was analysed. One hundred and five strains from different sources harboured 5-15 of the analysed non-LEE-encoded effector genes. In 101 of these strains, the LEE genes eae, map, espF and espG were present simultaneously. Thirty-one isolates deriving mainly from food and patients suffering from haemolytic uraemic syndrome (HUS) were eae-negative and did not carry any of the analysed effector genes. By combination of MLST and virulence gene data, we defined five genetic clusters. Within these clusters a clear-cut affiliation of particular sequence types and the occurrence of certain effector genes was observed. However, in contrast to other studies, a significant correlation between the amount and type of effector genes and the risk to cause HUS could not be demonstrated.
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Affiliation(s)
- Kristina Creuzburg
- Department of Food Microbiology, Institute of Food Science and Biotechnology, Garbenstraße 28, University of Hohenheim, 70599 Stuttgart, Germany
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Genome dynamics and its impact on evolution of Escherichia coli. Med Microbiol Immunol 2010; 199:145-54. [PMID: 20445988 DOI: 10.1007/s00430-010-0161-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Indexed: 02/08/2023]
Abstract
The Escherichia coli genome consists of a conserved part, the so-called core genome, which encodes essential cellular functions and of a flexible, strain-specific part. Genes that belong to the flexible genome code for factors involved in bacterial fitness and adaptation to different environments. Adaptation includes increase in fitness and colonization capacity. Pathogenic as well as non-pathogenic bacteria carry mobile and accessory genetic elements such as plasmids, bacteriophages, genomic islands and others, which code for functions required for proper adaptation. Escherichia coli is a very good example to study the interdependency of genome architecture and lifestyle of bacteria. Thus, these species include pathogenic variants as well as commensal bacteria adapted to different host organisms. In Escherichia coli, various genetic elements encode for pathogenicity factors as well as factors, which increase the fitness of non-pathogenic bacteria. The processes of genome dynamics, such as gene transfer, genome reduction, rearrangements as well as point mutations contribute to the adaptation of the bacteria into particular environments. Using Escherichia coli model organisms, such as uropathogenic strain 536 or commensal strain Nissle 1917, we studied mechanisms of genome dynamics and discuss these processes in the light of the evolution of microbes.
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Klapproth JMA. The role of lymphostatin/EHEC factor for adherence-1 in the pathogenesis of gram negative infection. Toxins (Basel) 2010; 2:954-62. [PMID: 22069619 PMCID: PMC3153230 DOI: 10.3390/toxins2050954] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2010] [Revised: 04/22/2010] [Accepted: 04/27/2010] [Indexed: 02/02/2023] Open
Abstract
Lymphostatin/EHEC factor for adherence-1 is a novel large toxin represented in various Gram negative bacteria, highly associated with the development of infectious diarrhea and hemolytic uremic syndrome. In vitro and in vivo experiments identified lymphostatin/EFA-1 as a toxin with a central role in the pathogenesis of Gram negative bacteria, responsible for bacterial adhesion, intestinal colonization, immunosuppression, and disruption of gut epithelial barrier function.
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Comparative genomics reveal the mechanism of the parallel evolution of O157 and non-O157 enterohemorrhagic Escherichia coli. Proc Natl Acad Sci U S A 2009; 106:17939-44. [PMID: 19815525 DOI: 10.1073/pnas.0903585106] [Citation(s) in RCA: 258] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Among the various pathogenic Escherichia coli strains, enterohemorrhagic E. coli (EHEC) is the most devastating. Although serotype O157:H7 strains are the most prevalent, strains of different serotypes also possess similar pathogenic potential. Here, we present the results of a genomic comparison between EHECs of serotype O157, O26, O111, and O103, as well as 21 other, fully sequenced E. coli/Shigella strains. All EHECs have much larger genomes (5.5-5.9 Mb) than the other strains and contain surprisingly large numbers of prophages and integrative elements (IEs). The gene contents of the 4 EHECs do not follow the phylogenetic relationships of the strains, and they share virulence genes for Shiga toxins and many other factors. We found many lambdoid phages, IEs, and virulence plasmids that carry the same or similar virulence genes but have distinct evolutionary histories, indicating that independent acquisition of these mobile genetic elements has driven the evolution of each EHEC. Particularly interesting is the evolution of the type III secretion system (T3SS). We found that the T3SS of EHECs is composed of genes that were introduced by 3 different types of genetic elements: an IE referred to as the locus of enterocyte effacement, which encodes a central part of the T3SS; SpLE3-like IEs; and lambdoid phages carrying numerous T3SS effector genes and other T3SS-related genes. Our data demonstrate how E. coli strains of different phylogenies can independently evolve into EHECs, providing unique insights into the mechanisms underlying the parallel evolution of complex virulence systems in bacteria.
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Abu-Ali GS, Lacher DW, Wick LM, Qi W, Whittam TS. Genomic diversity of pathogenic Escherichia coli of the EHEC 2 clonal complex. BMC Genomics 2009; 10:296. [PMID: 19575794 PMCID: PMC2713265 DOI: 10.1186/1471-2164-10-296] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 07/03/2009] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Evolutionary analyses of enterohemorrhagic Escherichia coli (EHEC) have identified two distantly related clonal groups: EHEC 1, including serotype O157:H7 and its inferred ancestor O55:H7; and EHEC 2, comprised of several serogroups (O26, O111, O118, etc.). These two clonal groups differ in their virulence and global distribution. Although several fully annotated genomic sequences exist for strains of serotype O157:H7, much less is known about the genomic composition of EHEC 2. In this study, we analyzed a set of 24 clinical EHEC 2 strains representing serotypes O26:H11, O111:H8/H11, O118:H16, O153:H11 and O15:H11 from humans and animals by comparative genomic hybridization (CGH) on an oligoarray based on the O157:H7 Sakai genome. RESULTS Backbone genes, defined as genes shared by Sakai and K-12, were highly conserved in EHEC 2. The proportion of Sakai phage genes in EHEC 2 was substantially greater than that of Sakai-specific bacterial (non-phage) genes. This proportion was inverted in O55:H7, reiterating that a subset of Sakai bacterial genes is specific to EHEC 1. Split decomposition analysis of gene content revealed that O111:H8 was more genetically uniform and distinct from other EHEC 2 strains, with respect to the Sakai O157:H7 gene distribution. Serotype O26:H11 was the most heterogeneous EHEC 2 subpopulation, comprised of strains with the highest as well as the lowest levels of Sakai gene content conservation. Of the 979 parsimoniously informative genes, 15% were found to be compatible and their distribution in EHEC 2 clustered O111:H8 and O118:H16 strains by serotype. CGH data suggested divergence of the LEE island from the LEE1 to the LEE4 operon, and also between animal and human isolates irrespective of serotype. No correlation was found between gene contents and geographic locations of EHEC 2 strains. CONCLUSION The gene content variation of phage-related genes in EHEC 2 strains supports the hypothesis that extensive modular shuffling of mobile DNA elements has occurred among EHEC strains. These results suggest that EHEC 2 is a multiform pathogenic clonal complex, characterized by substantial intra-serotype genetic variation. The heterogeneous distribution of mobile elements has impacted the diversification of O26:H11 more than other EHEC 2 serotypes.
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Affiliation(s)
- Galeb S Abu-Ali
- Microbial Evolution Laboratory, National Food Safety & Toxicology Center, 165 Food Safety & Toxicology Building, Michigan State University, East Lansing, Michigan 48824, USA
| | - David W Lacher
- Division of Molecular Biology, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland 20708, USA
| | - Lukas M Wick
- Biosynth AG, Rietlistrasse 4, 9422 Staad, Switzerland
| | - Weihong Qi
- Functional Genomics Center Zurich, University of Zurich and Swiss Federal Institute of Technology Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Thomas S Whittam
- Microbial Evolution Laboratory, National Food Safety & Toxicology Center, 165 Food Safety & Toxicology Building, Michigan State University, East Lansing, Michigan 48824, USA
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Comparative analysis of the locus of enterocyte effacement and its flanking regions. Infect Immun 2009; 77:3501-13. [PMID: 19506015 DOI: 10.1128/iai.00090-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The attaching-and-effacing (A/E) phenotype mediated by factors derived from the locus of enterocyte effacement (LEE) is a hallmark of clinically important intestinal pathotypes of Escherichia coli, including enteropathogenic (EPEC), atypical EPEC (ATEC), and enterohemorrhagic E. coli strains. Epidemiological studies indicate that the frequency of diarrhea outbreaks caused by ATEC is increasing. Hence, it is of major importance to further characterize putative factors contributing to the pathogenicity of these strains and to gain additional insight into the plasticity and evolutionary aspects of this emerging pathotype. Here, we analyzed the two clinical ATEC isolates B6 (O26:K60) and 9812 (O128:H2) and compared the genetic organizations, flanking regions, and chromosomal insertion loci of their LEE with those of the LEE of other A/E pathogens. Our analysis shows that the core LEE is largely conserved-particularly among genes coding for the type 3 secretion system-whereas genes encoding effector proteins display a higher variability. Chromosomal insertion loci appear to be restricted to selC, pheU, and pheV. In contrast, striking differences were found between the 5'- and 3'-associated flanking regions reflecting the different histories of the various strains and also possibly indicating different lines in evolution.
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Hernandes RT, Elias WP, Vieira MAM, Gomes TAT. An overview of atypical enteropathogenic Escherichia coli. FEMS Microbiol Lett 2009; 297:137-49. [PMID: 19527295 DOI: 10.1111/j.1574-6968.2009.01664.x] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The enteropathogenic Escherichia coli (EPEC) pathotype is currently divided into two groups, typical EPEC (tEPEC) and atypical EPEC (aEPEC). The property that distinguishes these two groups is the presence of the EPEC adherence factor plasmid, which is only found in tEPEC. aEPEC strains are emerging enteropathogens that have been detected worldwide. Herein, we review the serotypes, virulence properties, genetic relationships, epidemiology, reservoir and diagnosis of aEPEC, including those strains not belonging to the classical EPEC serogroups (nonclassical EPEC serogroups). The large variety of serotypes and genetic virulence properties of aEPEC strains from nonclassical EPEC serogroups makes it difficult to determine which strains are truly pathogenic.
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Affiliation(s)
- Rodrigo T Hernandes
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Brazil
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30
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Kelly B, Vespermann A, Bolton D. The role of horizontal gene transfer in the evolution of selected foodborne bacterial pathogens. Food Chem Toxicol 2009; 47:951-68. [DOI: 10.1016/j.fct.2008.02.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Revised: 02/04/2008] [Accepted: 02/06/2008] [Indexed: 10/22/2022]
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Badea L, Beatson SA, Kaparakis M, Ferrero RL, Hartland EL. Secretion of flagellin by the LEE-encoded type III secretion system of enteropathogenic Escherichia coli. BMC Microbiol 2009; 9:30. [PMID: 19200386 PMCID: PMC2647546 DOI: 10.1186/1471-2180-9-30] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 02/06/2009] [Indexed: 12/29/2022] Open
Abstract
Background Enteropathogenic Escherichia coli (EPEC) is an attaching and effacing (A/E) pathogen that possesses a type III secretion system (T3SS) encoded within the locus of enterocyte effacement (LEE). The LEE is essential for A/E lesion formation and directs the secretion and translocation of multiple LEE-encoded and non-LEE encoded effector proteins into the cytosol of infected cells. In this study we used proteomics to compare proteins exported to the culture supernatant by wild type EPEC E2348/69, a ΔespADB mutant and a ΔescF T3SS mutant. Results We observed that flagellin was consistently and strongly present in the secretome of wild type EPEC and the ΔespADB mutant but present only weakly in the secretome of the ΔescF mutant. Given the ancestral relationship between the flagella export apparatus and virulence associated T3SSs, we investigated whether FliC could utilise the LEE-encoded T3SS for export. In the absence of a functional flagella export apparatus, we showed that FliC could be secreted by the LEE-encoded T3SS and stimulate (Toll-like receptor 5) TLR5 signalling but could not confer motility. Conclusion Since the secretion of FliC during A/E lesion formation would presumably be disadvantageous for the pathogen, we propose that virulence associated T3SSs and flagella T3SSs have evolved through a system of chaperones and complex regulatory pathways to be functional at different times to ensure that FliC secretion does not occur during T3SS effector translocation.
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Affiliation(s)
- Luminita Badea
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia.
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Systematic identification and sequence analysis of the genomic islands of the enteropathogenic Escherichia coli strain B171-8 by the combined use of whole-genome PCR scanning and fosmid mapping. J Bacteriol 2008; 190:6948-60. [PMID: 18757547 DOI: 10.1128/jb.00625-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are diarrheagenic pathogens that colonize the intestinal tract through the formation of attaching and effacing lesions, induced by effectors translocated via a type III secretion system (T3SS) encoded on the locus of enterocyte effacement (LEE). In EHEC O157, numerous virulence factors, including around 40 T3SS effectors, have been identified. Most of them are encoded on genomic islands (GEIs) such as prophages and integrative elements. For EPEC, however, no systematic search of GEIs and virulence-related genes carried therein has been done, and only a limited number of virulence factors have been identified so far. In this study, we performed a systemic and genome-wide survey of the GEIs in strain B171-8, one of the prototype strains of EPEC, by the combined use of whole-genome PCR scanning and fosmid mapping and identified 22 large GEIs, including nine lambda-like prophages, three P2-like prophages, the LEE, and three additional integrative elements. On these prophages and integrative elements, we found genes for a set of T3SS proteins, a total of 33 T3SS effectors or effector homologues, and 12 other virulence factors which include five nonfimbrial adhesins. Most of the T3SS effector families identified are also present in EHEC O157, but B171-8 possesses a significantly smaller number of effectors. Not only the presence or absence of Shiga toxin genes but also the difference in the T3SS effector repertoire should be considered in analyzing the pathogenicity of EPEC and EHEC strains.
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Genomic O island 122, locus for enterocyte effacement, and the evolution of virulent verocytotoxin-producing Escherichia coli. J Bacteriol 2008; 190:5832-40. [PMID: 18586943 DOI: 10.1128/jb.00480-08] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The locus of enterocyte effacement (LEE) and genomic O island 122 (OI-122) are pathogenicity islands in verocytotoxin-producing Escherichia coli (VTEC) serotypes that are associated with outbreaks and serious disease. Composed of three modules, OI-122 may occur as "complete" (with all three modules) or "incomplete" (with one or two modules) in different strains. OI-122 encodes two non-LEE effector (Nle) molecules that are secreted by the LEE type III secretion system, and LEE and OI-122 are cointegrated in some VTEC strains. Thus, they are functionally linked, but little is known about the patterns of acquisition of these codependent islands. To examine this, we conducted a population genetics analysis, using multilocus sequence typing (MLST), with 72 VTEC strains (classified into seropathotypes A to E) and superimposed on the results the LEE and OI-122 contents of these organisms. The wide distribution of LEE and OI-122 modules among MLST clonal groups corroborates the hypothesis that there has been lateral transfer of both pathogenicity islands. Sequence analysis of a pagC-like gene in OI-122 module 1 also revealed two nonsynonymous single-nucleotide polymorphisms that could help discriminate a subset of seropathotype C strains and determine the presence of the LEE. A nonsense mutation was found in this gene in five less virulent strains, consistent with a decaying or inactive gene. The modular nature of OI-122 could be explained by the acquisition of modules by lateral transfer, either singly or as a group, and by degeneration of genes within modules. Correlations between clonal group, seropathotype, and LEE and OI-122 content provide insight into the role of genomic islands in VTEC evolution.
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Bielaszewska M, Sonntag AK, Schmidt MA, Karch H. Presence of virulence and fitness gene modules of enterohemorrhagic Escherichia coli in atypical enteropathogenic Escherichia coli O26. Microbes Infect 2007; 9:891-7. [PMID: 17544311 DOI: 10.1016/j.micinf.2007.03.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 03/12/2007] [Accepted: 03/13/2007] [Indexed: 10/23/2022]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains of serogroup O26 cause hemolytic-uremic syndrome (HUS) whereas atypical enteropathogenic E. coli (aEPEC) O26 typically cause uncomplicated diarrhea but have been also isolated from HUS patients. To gain insight into the virulence of aEPEC O26, we compared the presence of O island (OI) 122, which is associated with enhanced virulence in EHEC strains, among aEPEC O26 and EHEC O26 clinical isolates. We also tested these strains for the high pathogenicity island (HPI) which is a fitness island. All 20 aEPEC O26 and 20 EHEC O26 investigated contained virulence genes located within OI-122 (efa1/lifA, nleB, nleE, ent). In both aEPEC O26 and EHEC O26, OI-122 was linked to the locus for enterocyte effacement, forming a mosaic island which was integrated in pheU. Moreover, strains of these two pathotypes shared a conserved HPI. These data support a close relatedness between aEPEC O26 and EHEC O26 and have evolutionary implications. The presence of OI-122 in aEPEC O26 might contribute to their pathogenic potential.
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Affiliation(s)
- Martina Bielaszewska
- Institute for Hygiene, and the National Consulting Laboratory on Hemolytic Uremic Syndrome, University of Münster, Robert Koch Strasse 41, D-48149 Münster, Germany.
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Tobe T, Beatson SA, Taniguchi H, Abe H, Bailey CM, Fivian A, Younis R, Matthews S, Marches O, Frankel G, Hayashi T, Pallen MJ. An extensive repertoire of type III secretion effectors in Escherichia coli O157 and the role of lambdoid phages in their dissemination. Proc Natl Acad Sci U S A 2006; 103:14941-6. [PMID: 16990433 PMCID: PMC1595455 DOI: 10.1073/pnas.0604891103] [Citation(s) in RCA: 358] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Several pathogenic strains of Escherichia coli exploit type III secretion to inject "effector proteins" into human cells, which then subvert eukaryotic cell biology to the bacterium's advantage. We have exploited bioinformatics and experimental approaches to establish that the effector repertoire in the Sakai strain of enterohemorrhagic E. coli (EHEC) O157:H7 is much larger than previously thought. Homology searches led to the identification of >60 putative effector genes. Thirteen of these were judged to be likely pseudogenes, whereas 49 were judged to be potentially functional. In total, 39 proteins were confirmed experimentally as effectors: 31 through proteomics and 28 through translocation assays. At the protein level, the EHEC effector sequences fall into >20 families. The largest family, the NleG family, contains 14 members in the Sakai strain alone. EHEC also harbors functional homologs of effectors from plant pathogens (HopPtoH, HopW, AvrA) and from Shigella (OspD, OspE, OspG), and two additional members of the Map/IpgB family. Genes encoding proven or predicted effectors occur in >20 exchangeable effector loci scattered throughout the chromosome. Crucially, the majority of functional effector genes are encoded by nine exchangeable effector loci that lie within lambdoid prophages. Thus, type III secretion in E. coli is linked to a vast phage "metagenome," acting as a crucible for the evolution of pathogenicity.
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Affiliation(s)
- Toru Tobe
- *Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
- To whom correspondence may be addressed. E-mail:
or
| | - Scott A. Beatson
- University of Birmingham Medical School, Birmingham, B15 2TT, United Kingdom
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane QLD 4072, Australia
| | - Hisaaki Taniguchi
- Institute of Enzyme Research, University of Tokushima, 3-8-15 Kuramoto, Tokushima 770-8503, Japan
| | - Hiroyuki Abe
- *Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | - Amanda Fivian
- University of Birmingham Medical School, Birmingham, B15 2TT, United Kingdom
| | - Rasha Younis
- University of Birmingham Medical School, Birmingham, B15 2TT, United Kingdom
| | - Sophie Matthews
- University of Birmingham Medical School, Birmingham, B15 2TT, United Kingdom
| | - Olivier Marches
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Gad Frankel
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, United Kingdom; and
| | - Tetsuya Hayashi
- **Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 899-1692, Japan
| | - Mark J. Pallen
- University of Birmingham Medical School, Birmingham, B15 2TT, United Kingdom
- To whom correspondence may be addressed. E-mail:
or
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Hochhut B, Wilde C, Balling G, Middendorf B, Dobrindt U, Brzuszkiewicz E, Gottschalk G, Carniel E, Hacker J. Role of pathogenicity island-associated integrases in the genome plasticity of uropathogenic Escherichia coli strain 536. Mol Microbiol 2006; 61:584-95. [PMID: 16879640 DOI: 10.1111/j.1365-2958.2006.05255.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The genome of uropathogenic Escherichia coli isolate 536 contains five well-characterized pathogenicity islands (PAIs) encoding key virulence factors of this strain. Except PAI IV(536), the four other PAIs of strain 536 are flanked by direct repeats (DRs), carry intact integrase genes and are able to excise site-specifically from the chromosome. Genome screening of strain 536 identified a sixth putative asnW-associated PAI. Despite the presence of DRs and an intact integrase gene, excision of this island was not detected. To investigate the role of PAI-encoded integrases for the recombination process the int genes of each unstable island of strain 536 were inactivated. For PAI I(536) and PAI II(536), their respective P4-like integrase was required for their excision. PAI III(536) carries two integrase genes, intA, encoding an SfX-like integrase, and intB, coding for an integrase with weak similarity to P4-like integrases. Only intB was required for site-specific excision of this island. For PAI V(536), excision could not be abolished after deleting its P4-like integrase gene but additional deletion of the PAI II(536)-specific integrase gene was required. Therefore, although all mediated by P4-like integrases, the activity of the PAI excision machinery is most often restricted to its cognate island. This work also demonstrates for the first time the existence of a cross-talk between integrases of different PAIs and shows that this cross-talk is unidirectional.
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Affiliation(s)
- Bianca Hochhut
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, 97070 Würzburg, Germany
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Adams MA, Singh VK, Keller BO, Jia Z. Structural and biochemical characterization of gentisate 1,2-dioxygenase from Escherichia coli O157:H7. Mol Microbiol 2006; 61:1469-84. [PMID: 16930152 DOI: 10.1111/j.1365-2958.2006.05334.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gentisic acid (2,5-dihydroxybenzoic acid) is a key intermediate in aerobic bacterial pathways that are responsible for the metabolism of a large number of aromatic compounds. The critical step of these pathways is the oxygen-dependent reaction catalysed by gentisate 1,2-dioxygenase which opens the aromatic ring of gentisate to form maleylpyruvate. From gentisic acid, the cell derives carbon and energy through the conversion of maleylpyruvate to central metabolites. We have confirmed the annotation of a gentisate 1,2-dioygenase from the pathogenic O157:H7 Escherichia coli strain and present the first structural characterization of this family of enzymes. The identity of the reaction product was revealed using tandem mass spectroscopy. The operon responsible for the degradation of gentisate in this organism exhibits a high degree of conservation with the gentisate-degrading operons of other pathogenic bacteria, including the Shiga toxin-producing E. coli O103:H2, but does not appear to be present in non-pathogenic strains. The acquisition of the gentisate operon may represent a special adaptation to meet carbon source requirements under conditions of environmental stress and may provide a selective advantage for enterohaemorrhagic E. coli relative to their non-pathogenic counterparts.
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Affiliation(s)
- Melanie A Adams
- Department of Biochemistry, Queen's University, Kingston, ON, Canada K7L 3N6
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Muniesa M, Schembri MA, Hauf N, Chakraborty T. Active genetic elements present in the locus of enterocyte effacement in Escherichia coli O26 and their role in mobility. Infect Immun 2006; 74:4190-9. [PMID: 16790794 PMCID: PMC1489727 DOI: 10.1128/iai.00926-05] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The locus of enterocyte effacement (LEE) is a large multigene chromosomal segment encoding gene products responsible for the generation of attaching and effacing lesions in many diarrheagenic Escherichia coli strains. A recently sequenced LEE harboring a pathogenicity island (PAI) from a Shiga toxin E. coli serotype O26 strain revealed a LEE PAI (designated LEE O26) almost identical to that obtained from a rabbit-specific enteropathogenic O15:H- strain. LEE O26 comprises 59,540 bp and is inserted at 94 min within the mature pheU tRNA locus. The LEE O26 PAI is flanked by two direct repeats of 137 and 136 bp (DR1 and DR2), as well as a gene encoding an integrase belonging to the P4 integrase family. We examined LEE O26 for horizontal gene transfer. By generating mini-LEE plasmids harboring only DR1 or DR2 with or without the integrase-like gene, we devised a simple assay to examine recombination processes between these sequences. Recombination was shown to be integrase dependent in a DeltarecA E. coli K-12 strain background. Recombinant plasmids harboring a single direct repeat cloned either with or without the LEE O26 integrase gene were found to insert within the chromosomal pheU locus of E. coli K-12 strains with equal efficiency, suggesting that an endogenous P4-like integrase can substitute for this activity. An integrase with strong homology to the LEE O26 integrase was detected on the K-12 chromosome associated with the leuX tRNA locus at 97 min. Strains deleted for this integrase demonstrated a reduction in the insertion frequency of plasmids harboring only the DR into the pheU locus. These results provide strong evidence that LEE-harboring elements are indeed mobile and suggest that closely related integrases present on the chromosome of E. coli strains contribute to the dynamics of PAI mobility.
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Affiliation(s)
- Maite Muniesa
- School of Molecular and Microbial Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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Genka H, Baba T, Tsuda M, Kanaya S, Mori H, Yoshida T, Noguchi MT, Tsuchiya K, Sawada H. Comparative analysis of argK-tox clusters and their flanking regions in phaseolotoxin-producing Pseudomonas syringae pathovars. J Mol Evol 2006; 63:401-14. [PMID: 16927007 DOI: 10.1007/s00239-005-0271-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2005] [Accepted: 04/27/2006] [Indexed: 11/29/2022]
Abstract
DNA fragments containing argK-tox clusters and their flanking regions were cloned from the chromosomes of Pseudomonas syringae pathovar (pv.) actinidiae strain KW-11 (ACT) and P. syringae pv. phaseolicola strain MAFF 302282 (PHA), and then their sequences were determined. Comparative analysis of these sequences and the sequences of P. syringae pv. tomato DC3000 (TOM) (Buell et al., Proc Natl Acad Sci USA 100:10181-10186, 2003) and pv. syringae B728a (SYR) (Feil et al., Proc Natl Acad Sci USA 102:11064-11069, 2005) revealed that the chromosomal backbone regions of ACT and TOM shared a high similarity to each other but presented a low similarity to those of PHA and SYR. Nevertheless, almost-identical DNA regions of about 38 kb were confirmed to be present on the chromosomes of both ACT and PHA, which we named "tox islands." The facts that the GC content of such tox islands was 6% lower than that of the chromosomal backbone regions of P. syringae, and that argK-tox clusters, which are considered to be of exogenous origin based on our previous studies (Sawada et al., J Mol Evol 54:437-457, 2002), were confirmed to be contained within the tox islands, suggested that the tox islands were an exogenous, mobile genetic element inserted into the chromosomes of P. syringae strains. It was also predicted that the tox islands integrated site-specifically into the homologous sites of the chromosomes of ACT and PHA in the same direction, respectively, wherein 34 common gene coding sequences (CDSs) existed. Furthermore, at the left end of the tox islands were three CDSs, which encoded polypeptides and had similarities to the members of the tyrosine recombinase family, suggesting that these putative site-specific recombinases were involved in the recent horizontal transfer of tox islands.
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Affiliation(s)
- Hiroyuki Genka
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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Manson JM, Gilmore MS. Pathogenicity island integrase cross-talk: a potential new tool for virulence modulation. Mol Microbiol 2006; 61:555-9. [PMID: 16879637 DOI: 10.1111/j.1365-2958.2006.05262.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Instability and excision of pathogenicity islands (PAIs) have already been described in Escherichia coli 536. In this edition of Molecular Microbiology, Bianca Hochhut and colleagues from the University of Würzburg in Germany have shown that the instability of four of the E. coli 536 PAIs is mediated by a P4-type integrase encoded within the specific PAI by a site-specific recombination mechanism. The integrase encoded on PAI II(536) is able to mediate excision and integration of both PAI II(536), and also PAI V(536). The att sites of both these PAIs have a region of sequence similarity, which is also found in several other PAIs and in tRNA genes in several bacterial species. The cross-PAI activity of this integrase (Int(PAI II)) suggests that it plays an important role in both genome evolution and horizontal transfer of pathogenicity elements, possibly even across species barriers. Deletion of PAIs that carry genes for adhesins and other traits might lead to a phase variation-like phenomenon. Differential regulation of integrase activity or production might add a further level of fine-tuning during bacterial infection.
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Affiliation(s)
- Janet M Manson
- Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
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Kelly M, Hart E, Mundy R, Marchès O, Wiles S, Badea L, Luck S, Tauschek M, Frankel G, Robins-Browne RM, Hartland EL. Essential role of the type III secretion system effector NleB in colonization of mice by Citrobacter rodentium. Infect Immun 2006; 74:2328-37. [PMID: 16552063 PMCID: PMC1418941 DOI: 10.1128/iai.74.4.2328-2337.2006] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Attaching and effacing (A/E) pathogens are a significant cause of gastrointestinal illness in humans and animals. All A/E pathogens carry a large pathogenicity island, termed the locus for enterocyte effacement (LEE), which encodes a type III secretion system that translocates several effector proteins into host cells. To identify novel virulence determinants in A/E pathogens, we performed a signature-tagged mutagenesis screen in C57BL/6 mice by using the mouse A/E pathogen Citrobacter rodentium. Five hundred seventy-six derivatives of C. rodentium were tested in pools of 12 mutants. One attenuated mutant carried a transposon insertion in nleB, which encodes a putative effector of the LEE-encoded type III secretion system (T3SS). nleB is present in a genomic pathogenicity island that also encodes another putative effector, NleE, immediately downstream. Using translational fusions with beta-lactamase (TEM-1), we showed that both NleB and NleE were translocated into host cells by the LEE-encoded T3SS of enteropathogenic Escherichia coli. In addition, deletion of the gene encoding NleB in C. rodentium resulted in reduced colonization of mice in single infections and reduced colonic hyperplasia. In contrast, the deletion of other non-LEE-encoded effector genes in C. rodentium, nleC, nleD, or nleE, had no effect on host colonization or disease. These results suggest that nleB encodes an important virulence determinant of A/E pathogens.
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Affiliation(s)
- Michelle Kelly
- Department of Microbiology, Monash University, Victoria 3800, Australia
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42
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Marchés O, Wiles S, Dziva F, La Ragione RM, Schüller S, Best A, Phillips AD, Hartland EL, Woodward MJ, Stevens MP, Frankel G. Characterization of two non-locus of enterocyte effacement-encoded type III-translocated effectors, NleC and NleD, in attaching and effacing pathogens. Infect Immun 2006; 73:8411-7. [PMID: 16299341 PMCID: PMC1307030 DOI: 10.1128/iai.73.12.8411-8417.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Intestinal colonization by enteropathogenic and enterohemorrhagic Escherichia coli requires the locus of enterocyte effacement-encoded type III secretion system. We report that NleC and NleD are translocated into host cells via this system. Deletion mutants induced attaching and effacing lesions in vitro, while infection of calves or lambs showed that neither gene was required for colonization.
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Affiliation(s)
- Olivier Marchés
- CMMI, Flowers Building, Imperial College London, London SW7 2AZ, United Kingdom
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43
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Abstract
Enterohemorrhagic Escherichia coli (EHEC) was first recognized as a cause of human disease in 1983 and is associated with diarrhea and hemorrhagic colitis, which may be complicated by life-threatening renal and neurological sequelae. EHEC are defined by their ability to produce one or more Shiga-like toxins (Stx), which mediate the systemic complications of EHEC infections, and to induce characteristic attaching and effacing lesions on intestinal epithelia, a phenotype that depends on the locus of enterocyte effacement. Acquisition of Stx-encoding bacteriophages by enteropathogenic E. coli is believed to have contributed to the evolution of EHEC, and consequently some virulence factors are conserved in both pathotypes. A key requirement for E. coli to colonize the intestines and produce disease is the ability to adhere to epithelial cells lining the gastrointestinal tract. Here, we review knowledge of the adhesins produced by EHEC and other Stx-producing E. coli, with emphasis on genetic, structural, and mechanistic aspects and their contribution to pathogenesis.
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Affiliation(s)
- Mark P Stevens
- Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire RG20 7NN, United Kingdom
| | - Timothy S Wallis
- Division of Microbiology, Institute for Animal Health, Compton Laboratory, Berkshire RG20 7NN, United Kingdom
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Shifflett DE, Clayburgh DR, Koutsouris A, Turner JR, Hecht GA. Enteropathogenic E. coli disrupts tight junction barrier function and structure in vivo. J Transl Med 2005; 85:1308-24. [PMID: 16127426 DOI: 10.1038/labinvest.3700330] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) infection disrupts tight junctions (TJs) and perturbs intestinal barrier function in vitro. E. coli secreted protein F (EspF) is, in large part, responsible for these physiological and morphological alterations. We recently reported that the C57BL/6J mouse is a valid in vivo model of EPEC infection as EPEC colonizes the intestinal epithelium and effaces microvilli. Our current aim was to examine the effects of EPEC on TJ structure and barrier function of the mouse intestine and to determine the role of EspF in vivo. C57BL/6J mice were gavaged with approximately 2 x 10(8) EPEC organisms or PBS. At 1 or 5 days postinfection, mice were killed and ileal and colonic tissue was mounted in Ussing chambers to determine barrier function (measured as transepithelial resistance) and short circuit current. TJ structure was analyzed by immunofluorescence microscopy. Wild-type (WT) EPEC significantly diminished the barrier function of ileal and colonic mucosa at 1 and 5 days postinfection. Deficits in barrier function correlated with redistribution of occludin in both tissues. Infection with an EPEC strain deficient of EspF (delta espF) had no effect on barrier function at 1 day postinfection. Furthermore, delta espF had no effect on ileal TJ morphology and minor alterations of colonic TJ morphology at 1 day postinfection. In contrast, at 5 days postinfection, WT EPEC and delta espF had similar effects on barrier function and occludin localization. In both cases this was associated with immune activation, as demonstrated by increased mucosal tumor necrosis factor-alpha levels 5 days postinfection. In conclusion, these data demonstrate that WT EPEC infection of 6-8-week-old C57BL/6J mice (1) significantly decreases barrier function in the ileum and colon (2) redistributes occludin in the ileum and colon and (3) is dependent upon EspF to induce TJ barrier defects at early, but not late, times postinfection.
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Affiliation(s)
- Donnie E Shifflett
- Department of Medicine, Section of Digestive Diseases and Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA
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Use of comparative genomics as a tool to assess the clinical and public health significance of emerging Shiga toxin-producing Escherichia coli serotypes. Meat Sci 2005; 71:62-71. [DOI: 10.1016/j.meatsci.2005.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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46
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Beutin L, Tao J, Feng L, Krause G, Zimmermann S, Gleier K, Xia Q, Wang L. Sequence analysis of the Escherichia coli O15 antigen gene cluster and development of a PCR assay for rapid detection of intestinal and extraintestinal pathogenic E. coli O15 strains. J Clin Microbiol 2005; 43:703-10. [PMID: 15695667 PMCID: PMC548065 DOI: 10.1128/jcm.43.2.703-710.2005] [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: 01/18/2023] Open
Abstract
A collection of 33 Escherichia coli serogroup O15 strains was studied with regard to O:H serotypes and virulence markers and for detection of the O-antigen-specific genes wzx and wzy. The strains were from nine different countries, originated from healthy or diseased humans and animals and from food, and were isolated between 1941 and 2003. On the basis of virulence markers and clinical data the strains could be split into different pathogroups, such as uropathogenic E. coli, enteropathogenic E. coli, Shiga toxin-producing E. coli, and enteroaggregative E. coli. H serotyping and genotyping of the flagellin (fliC) gene revealed 11 different H types and a close association between certain H types, virulence markers, and pathogroups was found. Nucleotide sequence analysis of the O-antigen gene cluster revealed putative genes for biosynthesis of O15 antigen. PCR assays were developed for sensitive and specific detection of the O15-antigen-specific genes wzx and wzy. The high pathotype diversity found in the collection of 33 O15 strains contrasted with the high level of similarity found in the genes specific to the O15 antigen. This might indicate that the O15 determinant has been spread by horizontal gene transfer to a number of genetically unrelated strains of E. coli.
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Affiliation(s)
- Lothar Beutin
- Division of Microbial Toxins, Robert Koch Institute, Berlin, Germany
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Beutin L, Kaulfuss S, Herold S, Oswald E, Schmidt H. Genetic analysis of enteropathogenic and enterohemorrhagic Escherichia coli serogroup O103 strains by molecular typing of virulence and housekeeping genes and pulsed-field gel electrophoresis. J Clin Microbiol 2005; 43:1552-63. [PMID: 15814965 PMCID: PMC1081317 DOI: 10.1128/jcm.43.4.1552-1563.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the genetic relationships of 54 Escherichia coli O103 strains from humans, animals, and meat by molecular typing of housekeeping and virulence genes and by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) of seven housekeeping genes revealed seven profiles, I through VII. MLST profiles I plus III cover 45 Shiga toxin-producing E. coli (STEC) O103:H2 strains from Australia, Canada, France, Germany, and Northern Ireland that are characterized by the intimin (eae) epsilon gene and carry enterohemorrhagic E. coli (EHEC) virulence plasmids. MLST profile II groups five human and animal enteropathogenic E. coli (EPEC) O103:H2 strains that were positive for intimin (eae) beta. Although strains belonging to MLST groups II and I plus III are closely related to each other (92.6% identity), major differences were found in the housekeeping icdA gene and in the virulence-associated genes eae and escD. E. coli O103 strains with MLST patterns IV to VII are genetically distant from MLST I, II, and III strains, as are the non-O103 E. coli strains EDL933 (O157), MG1655 (K-12), and CFT073 (O6). Comparison of MLST results with those of PFGE and virulence typing demonstrated that E. coli O103 STEC and EPEC have recently acquired different virulence genes and DNA rearrangements, causing alterations in their PFGE patterns. PFGE typing was very useful for identification of genetically closely related subgroups among MLST I strains, such as Stx2-producing STEC O103 strains from patients with hemolytic uremic syndrome. Analysis of virulence genes contributed to grouping of E. coli O103 strains into EPEC and STEC. Novel virulence markers, such as efa (EHEC factor for adherence), paa (porcine adherence factor), and cif (cell cycle-inhibiting factor), were found widely associated with E. coli O103 EPEC and STEC strains.
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Affiliation(s)
- Lothar Beutin
- Division of Microbial Toxins, Department of Biological Safety, Robert Koch Institute, Berlin, Germany
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Dow MA, Tóth I, Alexa P, Davies M, Malik A, Oswald E, Nagy B. Predominance of afr2 and ral fimbrial genes related to those encoding the K88 and CS31A fimbrial adhesins in enteropathogenic Escherichia coli isolates from rabbits with postweaning diarrhea in Central Europe. J Clin Microbiol 2005; 43:1366-71. [PMID: 15750109 PMCID: PMC1081305 DOI: 10.1128/jcm.43.3.1366-1371.2005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PCR tests designed in these studies identified three rabbit adhesive factor genes among 43 enteropathogenic E. coli (EPEC) strains: afr1 (2 strains), the F4(K88)/CS31A-related afr2 (10 strains), and ral (15 strains). Several EPEC strains (i.e., O153:H7 and O157:H2) lacked these genes but did adhere to HeLa cells and produced attaching and effacing lesions in rabbits.
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Affiliation(s)
- Mohamed A Dow
- Veterinary Medical Research Institute of the Hungarian Academy of Sciences, 1143 Budapest, Hungaria Str. 21, Budapest, Hungary
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49
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Deng W, Li Y, Hardwidge PR, Frey EA, Pfuetzner RA, Lee S, Gruenheid S, Strynakda NCJ, Puente JL, Finlay BB. Regulation of type III secretion hierarchy of translocators and effectors in attaching and effacing bacterial pathogens. Infect Immun 2005; 73:2135-46. [PMID: 15784556 PMCID: PMC1087438 DOI: 10.1128/iai.73.4.2135-2146.2005] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Human enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC), and the mouse pathogen Citrobacter rodentium (CR) belong to the family of attaching and effacing (A/E) bacterial pathogens. They possess the locus of enterocyte effacement (LEE) pathogenicity island, which encodes a type III secretion system. These pathogens secrete a number of proteins into culture media, including type III effector proteins and translocators that are required for the translocation of effectors into host cells. Preliminary evidence indicated that the LEE-encoded SepL and Rorf6/SepD may form a molecular switch that controls the secretion of translocators and effectors in CR. Here, we show that SepL and SepD indeed perform this function in A/E pathogens such as EHEC and EPEC. Their sepL and sepD mutants do not secrete translocators but exhibit enhanced secretion of effectors. We demonstrate that SepL and SepD interact with each other and that both SepL and SepD are localized to the bacterial membranes. Furthermore, we demonstrate that culture media influence the type III secretion profile of EHEC, EPEC, and CR and that low-calcium concentrations inhibit secretion of translocators but promote the secretion of effectors, similar to effects on type III secretion by mutations in sepL and sepD. However, the secretion profile of the sepD and sepL mutants is not affected by these culture conditions. Collectively, our results suggest that SepL and SepD not only are necessary for efficient translocator secretion in A/E pathogens but also control a switch from translocator to effector secretion by sensing certain environmental signals such as low calcium.
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Affiliation(s)
- Wanyin Deng
- Michael Smith Laboratories, University of British Columbia, 301-2185, East Mall, Vancouver, British Columbia V6T 1Z4, Canada
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50
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Jores J, Wagner S, Rumer L, Eichberg J, Laturnus C, Kirsch P, Schierack P, Tschäpe H, Wieler LH. Description of a 111-kb pathogenicity island (PAI) encoding various virulence features in the enterohemorrhagic E. coli (EHEC) strain RW1374 (O103:H2) and detection of a similar PAI in other EHEC strains of serotype 0103:H2. Int J Med Microbiol 2005; 294:417-25. [PMID: 15715170 DOI: 10.1016/j.ijmm.2004.09.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Human infections with enterohemorrhagic E. coli (EHEC) strains of serotype O103:H2 are of increasing importance in Germany. As bovines are the principal EHEC reservoir behind the occurrence of human infections, we analyzed a pathogenicity island (PAI I(RW1374)) of bovine O103:H2 strain RW1374 to identify putative virulence features. This PAI I(RW1374) harbors a functional 34-kb locus of enterocyte effacement (LEE) core region and has a total length of 111 kb. About 43 kb upstream of the LEE core a gene cassette consisting of efa1/lifA gene and flanking IS elements suggests another putative transposon within the PAI(IRW1374). In addition, the ent gene, encoding a Shigella ShET-2 enterotoxin homologue, is present about 57 kb upstream of the LEE core. This PAI is therefore a complex assembly of various virulence determinants including the efa1/lifA and the ent gene resembling O157:H7 PAI OI-122/SpLE3 as well as the LEE core region. An integrase gene on the very left end of PAI I(Rw1374) is disrupted by an IS629 homologue. In an attempt to mobilize the LEE core we performed conjugation, transformation and transduction experiments. We were, however, unable to mobilize the whole or even single regions of PAI I(RW1374). Comparative studies with other strains of serotype O103:H2 isolated from humans, bovines and food showed that they all harbored a similar phe V-inserted PAI including the virulence genes ent and lifA/efa1 as well as the large virulence-associated plasmid encoding the EHEC hemolysin. This combination of several virulence factors confirms the complex virulence of O103:H2 EHEC and may at least partly explain the high virulence of this EHEC serotype in humans.
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Affiliation(s)
- Joerg Jores
- Institut für Mikrobiologie und Tierseuchen, Freie Universität Berlin, Philippstrasse 13, D-10115 Berlin, Germany.
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