Molecular Genetic Characterization of Shiga Toxin-producing E. coli Isolated from Diarrhea Patients and Cattle in Gwangju Area, Korea

ABSTRACT

Shiga toxin-producing Escherichia coli (STEC) can cause a broad spectrum of human illness ranging from symptom-free to hemolytic uremic syndrom (HUS). Associations between known or putative virulence factors of STEC and diseases in human were investigated. PCR analyses showed that 33 (78.6%) isolates carried an ehxA enterohemolysin gene and 6 (14.3%) isolates possessed an saa autoaggutinating adhesin gene, and 31 (73.8%) isolates carried an eae intimin gene (7 isolates with type beta, 16 with type gamma, and 3 with type epsilon). Twenty-nine (69%) isolates from patients carried eae+, ehxA+, saa- (genotype A) and 68 (86%) isolates from asymptomatic outbreaks and 4 (36%) isolates from bovine possessed eae-, ehxA+, saa+ (genotype C). Neither the bundle-forming pilus gene nor the enteropathogenic E. coli adherence factor plasmid was found. In HEp-2 cell adherence assay, isolates carrying eae gene exhibited a localized adherence phenotype, the other isolates carrying saa showed LC (loose clusters of bacteria) and IS (isolated bacteria). In conclusion, most STEC isolated from cattle feces in Gwangju, Korea showed characteristics different from those isolated from patients. But these results may be useful information for pathogenesis judgement of STEC.