Detection of Shiga toxin-producing Escherichia coli in packaged salad and lettuce leaves sold in flea markets and supermarkets in Ulaanbaatar

Abstract

Background: A risk assessment by the WHO and the US Food and Agriculture Organizati on found that green leafy vegetables pose the highest risk of pathogen transmission. STEC infection can cause dysentery in elderly, immunocompromised people and young children, which can be complicated by acute kidney failure. Aim: To detect of STEC contamination in the packaged salad and lettuce leaves sold in flea markets and supermarkets. Materials and methods: The study samples, 40 of green salads, 25 of lettuces sold in flea market and supermarkets, were collected for detecting E.coli contamination by stx1 and stx2 genes of STEC. We use molecular biology methods to detect genes. Results: E.coli contamination was proved in 47.5% (n=19) of the packaged salad samples. On the other hand, in lettuce samples collected from flea markets and supermarkets, 16% (n=8) samples of flea market and 10% (n=5) samples of lettuce were detected E.coli contamination too. STEC strains which causing dysentery, renal failure, and foodborne illness were identified in 31.6% (n=6) of packaged salad samples and 25% (n=2) of lettuce samples. Conclusion: The green salad and lettuce are sold in in flea market and supermarkets are highly contaminated by E.coli. Moreover, the lettuce which are sold in flea markets are evaluated more contaminated than the others.