Genotypic and Phenotypic Characterization of EnteropathogenicEscherichia coliIsolated from Diarrheal Patients in Gwangju

Abstract

Enteropathogenic Escherichia coli (EPEC) have been implicated in human diarrhea in several countries. Central to EPEC-mediated disease is its ability to cause intestinal lesions, known as attaching and effacing (A/E) lesion. We investigated 92 EPEC strains isolated from patients with diarrhea in Gwangju for their genotypic and phenotypic characteristics. Sixteen (17.4%) of all strains were found to be typical EPEC because they were bfpA gene positive by PCR. The most of typical EPEC isolates (87.5%) showed a localized adhesion (LA) pattern in Hep-2 cell adherence assay, whereas, only 11 atypical EPEC isolates (14.5%) were adhered to Hep-2 cells in a localized manner. Thirteen of the EPEC strains studied belonged to classical O-serogroups of EPEC and 7 isolates were classified as nonclassical EPEC serogroup and the other isolates could not be serotyped with our antisera. The subtypes of eae, tir, espA and espB genes which are major virulence genes concerned of A/E lesion on chromosome were analyzed by multiplex PCR for finding the original resource. The results showed that the composition of these genes subtypes was homogenous and heterogenous in 12 and 26 isolates, respectively. The others were non-determined type in terms of the gene subtype because of genetic diversity of intimin-coding eae genes. Our findings indicated that EPEC isolates from patients with diarrhea were diverse genetically and phenotypically, which require further study in regard to their virulence and epidemiological significance.