Low prevalence of the 'gang of seven' and absence of the O80:H2 serotypes among Shigatoxigenic and enteropathogenic Escherichia coli (STEC and EPEC) in intestinal contents of healthy cattle at two slaughterhouses in Belgium in 2014

Abstract

Aims: The purpose of this survey was to estimate the respective prevalence of the 'gang of seven' and 'non-gang of seven' serotypes of Shigatoxigenic and enteropathogenic Escherichia coli and to identify the O80:H2 serotype in 245 intestinal contents collected at two slaughterhouses in Belgium in 2014.

Methods and results: After overnight enrichment growth, the 69 intestinal contents testing positive with PCR targeting the eae, stx1 and stx2 genes were inoculated onto four agar media. Of the 2542 colonies picked up, 677 from 59 samples were PCR confirmed. The most frequent virulotypes were eae+ in 47 (80%) samples, stx2+ in 20 (34%) samples and eae+ stx1+ in 16 (27%) samples. PCR-positive colonies belonged to different virulotypes in 36 samples. No colony was O80-positive, whereas two eae+ colonies from two samples were O26:H11, 50 eae+ stx1+ and eae+ from eight samples were O103:H2 and two eae+ stx1+ stx2+ colonies from one sample were O157:H7.

Conclusions: The 'non-gang of seven' serotypes are more frequent than the 'gang of seven' serotypes and the O80:H2 serotype was not detected among Shigatoxigenic and enteropathogenic Escherichia coli in the intestines of cattle at these two slaughterhouses.

Significance and impact of the study: Although the identification protocols of Shigatoxigenic Escherichia coli focus on the 'gang of seven' serotypes, several other serotypes can be present with possible importance in public health. Innovative selective identification procedures should be designed.

Keywords: Escherichia coli (all potentially pathogenic types); enterohaemorrhagic E. coli; genotyping; intestinal microbiology; veterinary.