A commensal gone bad: complete genome sequence of the prototypical enterotoxigenic Escherichia coli strain H10407.

In most cases Escherichia coli exists as a harmless commensal organism but may on occasion cause intestinal and/or extraintestinal disease. Enterotoxigenic E. coli are the predominant cause of E. coli-mediated diarrhea in the developing world and are responsible for a significant portion of paediatric deaths. In this study we determined the complete genomic sequence of E. coli H10407, a prototypical strain of enterotoxigenic E. coli, which reproducibly elicits diarrhea in human volunteer studies. We performed genomic and phylogenetic comparisons with other E. coli strains revealing that the chromosome is closely related to the non-pathogenic commensal strain E. coli HS and to the laboratory strains E. coli K-12 and C. Furthermore, these analyses demonstrated that there were no chromosomally-encoded factors unique to any sequenced ETEC strains. Comparison of the E. coli H10407 plasmids with those from several ETEC strains revealed the plasmids had a mosaic structure but that several loci were conserved amongst ETEC strains. This study provides a genetic context for the vast amount of experimental and epidemiological data published thus far.