Detection and characterization of Shiga toxin-producing Escherichia coli in game meat and ready-to-eat meat products

A total of 142 samples of game meat and ready-to-eat meat products from red deer and wild boar were analysed in order to assess the presence of Shiga toxin-producing Escherichia coli (STEC). Shiga-toxin encoding genes (stx genes) were detected by PCR in 36 (25.4%) of the samples and STEC was isolated from 8 (5.6%) of the same samples. None of the samples tested positive for E. coli O157:H7. Four different serotypes were found among the 8 STEC isolates, with serotype O27:H30 being predominant (62.5%, 5/8). The PCR assay indicated the presence of the stx2 gene in all of the STEC isolates and further subtyping resulted in detection of three different subtypes: stx2a, stx2b and stx2g. The only stx1-positive isolate was further subtyped as stx1c. The ehxA gene was detected in 3 (37.5%) of the isolates and none of them contained the eae gene. All STEC isolates were sensitive to the 13 antibiotics tested. Some isolates possessed serotypes and virulence gene profiles previously associated with STEC infections in humans. The isolation of a STEC strain carrying the stx2a subtype from a ready-to-eat meat product from deer suggests the role of these products as a potential source of STEC infections in humans.