Pathotypic Characterization of Enterocyte Effacement-related LEE Genes in EHEC and EPEC Isolated from Diarrheal Patients

Abstract

Attaching and effacing Escherichia coli (AEEC) cause enteric infections in humans and animals. Attaching indicates the intimate attachment of bacteria to the enterocyte, and effacing relates to the localized effacement of brush border microvilli. Enteropathogenic (EPEC) and enterohemorrhagic Escherichia coli (EHEC) infections are characterized by the formation of attaching and effacing (AE) lesion on the intestinal epithelial cells. Therefore, they are often grouped together as AEEC. Development of multiplex PCR allowed us to type five of the most important genes implicated in the formation of the AE lesion. A total of 60 AEEC strains isolated from diarrheal patients were investigated by multiplex PCR for the presence of the insertion site of locus of enterocyte effacement (LEE) and LEE-related (eae, tir, espA, espB, and espD) genes. Associating the results of LEE genes typing in the AEEC strains, three different pathotypes are determined: eae γ -tir γ -espA γ -espB γ -espD γ (O157:H7), eae β -tir β -espA β -espB β -espD β (O26:H11), and eae α -tir α -espA α -espB α -espD α (O55:H6). These results indicate that AEEC are a heterogenous groups of organisms.