Scientific Publications by FDA Staff

FEMS Microbiol Lett 2012 Dec;337(2):126-31

Clonal relations of atypical enteropathogenic Escherichia coli O157:H16 strains isolated from various sources from several countries.

Feng PC, Keys C, Lacher DW, Beutin L, Bentancor A, Heuvelink A, Afset JE, Rumi V, Monday S

Atypical enteropathogenic Escherichia coli (aEPEC) is comprised of a large heterogeneous group of strains and serotypes that carry the intimin gene (eae) but no other EPEC virulence factors. In a previous study, we examined a few aEPEC strains of O157:H16 serotype from the U.S. and France and found these to be nearly homologous, and speculated that the same strain had been disseminated or perhaps they are part of a large clonal group that exists worldwide. To test that hypothesis, we examined additional 45 strains isolated from various sources from 4 other countries and determined that although there are a few eae-negative O157:H16 strains, most are aEPEC that carried eae and specifically, the epsilon-eae allele. Analysis by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing showed that as a whole, O157:H16 strains are phylogenetically diverse and have different sequence types and PFGE profiles. But the aEPEC strains within the O157:H16 serotype, regardless of the eae allele carried, is a highly conserved and homologous group of Sequence type (ST)-171 strains that shared similar PFGE profiles. These aEPEC strains of O157:H16 serotype are not closely related to any of the major EPEC and EHEC clonal lineages and appear to be part of a large clonal group that are prevalent worldwide.