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      A complete view of the genetic diversity of the Escherichia coli O-antigen biosynthesis gene cluster

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          Abstract

          The O antigen constitutes the outermost part of the lipopolysaccharide layer in Gram-negative bacteria. The chemical composition and structure of the O antigen show high levels of variation even within a single species revealing itself as serological diversity. Here, we present a complete sequence set for the O-antigen biosynthesis gene clusters (O-AGCs) from all 184 recognized Escherichia coli O serogroups. By comparing these sequences, we identified 161 well-defined O-AGCs. Based on the wzx/ wzy or wzm/ wzt gene sequences, in addition to 145 singletons, 37 serogroups were placed into 16 groups. Furthermore, phylogenetic analysis of all the E. coli O-serogroup reference strains revealed that the nearly one-quarter of the 184 serogroups were found in the ST10 lineage, which may have a unique genetic background allowing a more successful exchange of O-AGCs. Our data provide a complete view of the genetic diversity of O-AGCs in E. coli showing a stronger association between host phylogenetic lineage and O-serogroup diversification than previously recognized. These data will be a valuable basis for developing a systematic molecular O-typing scheme that will allow traditional typing approaches to be linked to genomic exploration of E. coli diversity.

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          Most cited references 28

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          Shiga-toxin-producing Escherichia coli and haemolytic uraemic syndrome.

          Most cases of diarrhoea-associated haemolytic uraemic syndrome (HUS) are caused by Shiga-toxin-producing bacteria; the pathophysiology differs from that of thrombotic thrombocytopenic purpura. Among Shiga-toxin-producing Escherichia coli (STEC), O157:H7 has the strongest association worldwide with HUS. Many different vehicles, in addition to the commonly suspected ground (minced) beef, can transmit this pathogen to people. Antibiotics, antimotility agents, narcotics, and non-steroidal anti-inflammatory drugs should not be given to acutely infected patients, and we advise hospital admission and administration of intravenous fluids. Management of HUS remains supportive; there are no specific therapies to ameliorate the course. The vascular injury leading to HUS is likely to be well under way by the time infected patients seek medical attention for diarrhoea. The best way to prevent HUS is to prevent primary infection with Shiga-toxin-producing bacteria.
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            German outbreak of Escherichia coli O104:H4 associated with sprouts.

            A large outbreak of the hemolytic-uremic syndrome caused by Shiga-toxin-producing Escherichia coli O104:H4 occurred in Germany in May 2011. The source of infection was undetermined. We conducted a matched case-control study and a recipe-based restaurant cohort study, along with environmental, trace-back, and trace-forward investigations, to determine the source of infection. The case-control study included 26 case subjects with the hemolytic-uremic syndrome and 81 control subjects. The outbreak of illness was associated with sprout consumption in univariable analysis (matched odds ratio, 5.8; 95% confidence interval [CI], 1.2 to 29) and with sprout and cucumber consumption in multivariable analysis. Among case subjects, 25% reported having eaten sprouts, and 88% reported having eaten cucumbers. The recipe-based study among 10 groups of visitors to restaurant K included 152 persons, among whom bloody diarrhea or diarrhea confirmed to be associated with Shiga-toxin-producing E. coli developed in 31 (20%). Visitors who were served sprouts were significantly more likely to become ill (relative risk, 14.2; 95% CI, 2.6 to ∞). Sprout consumption explained 100% of cases. Trace-back investigation of sprouts from the distributor that supplied restaurant K led to producer A. All 41 case clusters with known trading connections could be explained by producer A. The outbreak strain could not be identified on seeds from the implicated lot. Our investigations identified sprouts as the most likely outbreak vehicle, underlining the need to take into account food items that may be overlooked during subjects' recall of consumption.
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              Multiple independent origins of Shigella clones of Escherichia coli and convergent evolution of many of their characteristics.

              The evolutionary relationships of 46 Shigella strains representing each of the serotypes belonging to the four traditional Shigella species (subgroups), Dysenteriae, Flexneri, Boydii, and Sonnei, were determined by sequencing of eight housekeeping genes in four regions of the chromosome. Analysis revealed a very similar evolutionary pattern for each region. Three clusters of strains were identified, each including strains from different subgroups. Cluster 1 contains the majority of Boydii and Dysenteriae strains (B1-4, B6, B8, B10, B14, and B18; and D3-7, D9, and D11-13) plus Flexneri 6 and 6A. Cluster 2 contains seven Boydii strains (B5, B7, B9, B11, B15, B16, and B17) and Dysenteriae 2. Cluster 3 contains one Boydii strain (B12) and the Flexneri serotypes 1-5 strains. Sonnei and three Dysenteriae strains (D1, D8, and D10) are outside of the three main clusters but, nonetheless, are clearly within Escherichia coli. Boydii 13 was found to be distantly related to E. coli. Shigella strains, like the other pathogenic forms of E. coli, do not have a single evolutionary origin, indicating convergent evolution of Shigella phenotypic properties. We estimate the three main Shigella clusters to have evolved within the last 35,000 to 270,000 years, suggesting that shigellosis was one of the early infectious diseases of humans.
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                Author and article information

                Journal
                DNA Res
                DNA Res
                dnares
                dnares
                DNA Research: An International Journal for Rapid Publication of Reports on Genes and Genomes
                Oxford University Press
                1340-2838
                1756-1663
                February 2015
                26 November 2014
                26 November 2014
                : 22
                : 1
                : 101-107
                Affiliations
                [1 ]Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki , Miyazaki 889-2192, Japan
                [2 ]Department of Bacteriology I, National Institute of Infectious Diseases , Tokyo 162-8640, Japan
                [3 ]Division of Parasitology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki , Miyazaki 889-1692, Japan
                [4 ]Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki , Miyazaki 889-1692, Japan
                [5 ]Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki , Miyazaki 889-1692, Japan
                [6 ]Pathogen Genomics, The Wellcome Trust Sanger Institute , Cambridge CB10 1SA, UK
                [7 ]Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine , London WC1E 7HT, UK
                Author notes
                [* ]To whom correspondence should be addressed. Tel/Fax. +81 985-58-7507. E-mail: iguchi@ 123456med.miyazaki-u.ac.jp

                Edited by Dr Katsumi Isono

                Article
                dsu043
                10.1093/dnares/dsu043
                4379981
                25428893
                © The Author 2014. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

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