Detection of SHIGA-TOXIN producing E. coli in some retail markets in Egypt using qPCR assay with special reference to serotyping

Background: Shiga toxin-producing Escherichia coli are dangerous foodborne pathogens that represent a severe public health issue worldwide. Raw foods are considered an important source of STEC infection in humans. Objective: In the current study, STEC contamination was investigated in 80 raw foods (chicken, beef, and milk) and water collected from different localities of Greater Cairo using Real-Time PCR. Moreover, the virulence genes of isolates were characterized. Results: STEC was detected in eight samples, (7 beef and 1 chicken), which represent about 10% of the tested samples. Positive beef and chicken samples show the presence of 13 and 2 STEC genes, respectively. Five samples were positive for eaeA (intemin), two samples were positive for stx1 gene and eight samples were positive for stx2 gene. Beef samples reveal the highest incidence of virulence gene stx2 (35%), followed by eaeA (20%), then stx1 (10%). The incidence of STEC was lower in chicken samples and the prevalence of virulence gene was 5% for stx2 and eaeA, respectively. Stx2 gene was the most prevalent subtype identified in beef samples. Serotyping of isolated STEC strains (14) revealed isolation of seven STEC strains belong to O157 serogroup, two strains belong to O111and five strains belong to serogroup O26. Conclusion: The current study concluded that recovery of STEC from raw chicken and beef samples is of important concern.