This Article Full Text (PDF) Other Versions of this Article: IAI.00956-07v1 76/2/845    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wu, G. Articles by Anjum, M. F. Search for Related Content PubMed PubMed Citation Articles by Wu, G. Articles by Anjum, M. F.

 Previous Article  |  Next Article 

Infect. Immun. doi:10.1128/IAI.00956-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Genetic Diversity among Escherichia coli O157:H7 Isolates and identification of genes linked to human infections

Department of Food and Environmental Safety, Veterinary Laboratories Agency (VLA)-Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT13 3NB, UK

^* To whom correspondence should be addressed. Email: g.wu{at}vla.defra.gsi.gov.uk.

	Abstract

An E. coli oligonucleotide microarray based on three sequenced genomes was validated for comparative genomic microarray hybridisation and used to study the diversity of E. coli O157 isolates from human infections, food and animal sources. Among 26 test strains, twenty-four (including both Shiga-toxin (Stx) positive and negative strains) were found to be related to the two sequenced E. coli O157:H7 strains, EDL933 and Sakai. However, these strains showed much greater genetic diversity than those had been reported previously, and most of them could not be categorised as either lineage I or II. Some genes were found more often in isolates from human than from non-human sources, e.g. ECs1202 and ECs2976 associated with stx2AB and stx1AB were in all isolates from human, but only in 40% of those from non-human sources. Some (but not all) lineage I specific or dominant genes were also more frequently associated with isolates from human. The results suggested that it might be more effective if we concentrate our efforts on finding markers that are directly related to infection rather than those specific to certain lineage in future. In addition, two Stx-negative O157 cattle isolates (one confirmed to be H7) were significantly different from other Stx-positive and negative E. coli O157:H7 strains, and were more similar to MG1655 in their gene content. This work has demonstrated that not all E. coli O157:H7 strains belong to the same clonal group and those that were similar to E. coli K-12 might be less virulent.