Purpose: Prevalence and pathogenic potentials of STEC isolates from retail meat products in Korea were evaluated.
Methods: During the years 2008-2009, a total of 912 retail meat products including beef, pork and chicken were collected in Korea. E. coli was isolated according to the Korean Food Standards Codex. Further identification of STEC was done by detection of the stx genes and O-serotyping. Antibiogram of individual STEC isolates was determined by disk diffusion or minimal inhibitory concentrations according to the guideline of clinical laboratory standard institute. The polymerase chain reactions were employed to detect the previously defined virulence genes in STEC, including Stx1 and 2 (stx1 & 2), enterohemolysin (ehxA), intimin (eaeA), STEC autoagglutination adhesin (saa) and subtilase cytotoxin (subAB). Stx production was analyzed quantitatively by a reverse phase latex agglutination (RPLA) kit.
Results: Among the 469 E. coli strains isolated during the experimental periods, 12 (2.6%) isolates contained the stx gene and belonged to 12 O-serogroups. They all carried stx1 and eae genes, but none of them had stx2, saa, and subAB genes. Six (50.0%) STEC isolates possessed the ehxA gene, which are known to be plasmid-encoded. As expected, the antibiogram profiles showed that some STEC strains, especially pork and chicken isolates, displayed a multiple drug resistance phenotype. The RPLA analysis revealed that all the STEC isolates produced Stx1 only at the undetectable levels.
Significance: Prevalence of STEC isolates and their pathogenic properties have been analyzed in Korea for the first time, implying that a unique pattern(s) might be present among the Korean STEC isolates.