AND ESCHERICHIA COLI O157 IN FATTENING PIGS AT

Abstract Feacal samples from 630 slaughtered healthy pigs were examined with the aim: (i) to monitor the shedding of non-O157 STEC and E. coli O157; (ii) to further characterize isolated strains; and (iii) to discuss the results obtained with their relevance to food safety. The percentage of the 630 samples testing positive for STEC by polymerase chain reaction was 22.2%. The 32 isolated stx positive strains (31 sorbitol-positive) belonged to non-O157 STEC and comprised ten serotypes. Stx1, stx2, and both toxin genes were detected in 3%, 97%, and 0 % of strains. Among stx2-positive strains, 29 were positive for stx2e, one for stx2/stx2e, and one for stx2c/stx2e. The percentage of the 630 samples testing positive for E. coli O157 by polymerase chain reaction was 7.5%. The 31 isolated rfbE PCR positive strains tested negative for stx genes. However, four strains harbored eae and were classified as EPEC. Introduction The importance of the Shiga toxin (Stx)-producing Escherichia coli (STEC) group has increased since a food-borne infection caused by STEC has first been reported in 1983 (Riley et al, 1983). Pathogenicity of STEC in humans is associated with diverse virulence factors. The main factors are the ability to form cytotoxic exotoxins (shiga toxins), which can be subdivided into a shiga toxin 1 group (Stx1 group) and a shiga toxin 2 group (Stx2 group), as well as the property o