Multiplex Real-Time PCR Assay for the Detection of LT, STIa and STIb Genes in Enterotoxigenic Escherichia coli

Abstract

Background: Diarrhea is an important cause of illness and death among all age groups on a global scale. Enterotoxigenic Escherichia coli (ETEC) protozoa were established as a causative agent of diarrhea in developing and developed countries. The identification of diarrheagenic E. coli (DEC) strains needs to detect the factors that determine the virulence of these organisms. Objectives: In this study, we aimed to use the multiplex real-time (MRT) and multiplex PCR assays for identification of ETEC in patients with diarrhea in Shiraz, Iran. Patients and Methods: A total of 430 stool samples were collected from patients with diarrhea in Shiraz, in 2012. Diarrheagenic E. coli (DEC) strains were isolated by standard biochemical analysis. We used MRT-PCR and multiplex PCR (MPCR) assays to detect the presence of LT, STΙa and STΙb genes in ETEC. Results: In this study, 430 stool samples were tested and 52 (12.1%) were identified as contaminated with E. coli using standard biochemical tests. The ETEC were detected in eight patients (15.4%) with diarrhea by the MRT-PCR and MPCR methods. The results of this study showed that four out of eight strains (50%) were STI a producer, and three out of eight strains were ST producers (37.5%). Also, one strain (12.5%) contained both STΙa and LT genes, simultaneously. Conclusions: This is the first study performed in Shiraz to identify ETEC intestinal pathogens in patients with diarrhea. The results of this study showed that MRT-PCR can be used as a replacement for the conventional MPCR assay to detect the ETEC strains.