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Appl. Environ. Microbiol. doi:10.1128/AEM.02855-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Identification of Unconventional Intestinal Pathogenic Escherichia coli Expressing Intermediate Virulence Factor Profiles with a Novel Single Step Multiplex PCR

Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung (ZMBE), Westfälische Wilhelms-Universität Münster, Institut für Hygiene, Universitätsklinikum Münster, D-48149 Münster, and Robert-Koch Institut, Bereich Wernigerode, D-38855 Wernigerode, Germany

^* To whom correspondence should be addressed. Email: infekt{at}uni-muenster.de or http://zmbe.uni-muenster.de.

	Abstract

Intestinal pathogenic Escherichia coli represent a global health problem for mammals, including humans. At present, diarrheagenic E. coli are grouped into seven major pathotypes that differ in their virulence factor profiles, severity of clinical manifestations, and prognosis. In this study, we developed and evaluated a one-step multiplex-PCR (MPCR) for the straightforward differential identification of intestinal pathotypes of E. coli. The specificity of this novel MPCR was validated using a subset of reference strains and further confirmed by PCR-independent pheno- and genotypic characterization. Moreover, we tested 246 clinical E. coli isolates derived from diarrhea patients from several distinct geographical regions. Interestingly, besides strains belonging to the defined and well-described pathotypes, we identified five unconventional strains expressing intermediate virulence factor profiles. These strains have been further characterized and appear to represent 'intermediate' strains carrying genes and expressing factors associated with enteropathogenic E. coli (EPEC), Shiga toxin-producing E. coli (STEC), enterotoxigenic E. coli (ETEC) and enteroaggregative E. coli (EAEC) alike. These strains represent further examples for the extraordinary plasticity of the E. coli genome. Moreover, this implies that the important identification of specific pathotypes has to be based on a broad matrix of indicator genes. In addition, the presence of 'intermediate' strains needs to be accounted for.