Detection of virulence genes in Shiga toxigenic Escherichia coli isolated from diarrhoeic and non-diarrhoeic pediatric patients in Ondo State, Nigeria

Abstract

Background: Shiga toxigenic Escherichia coli (STEC) is one of the major causes of intestinal infection, bloody and non-bloody diarrhoea and extra-intestinal complications in humans. It is therefore necessary to enumerate the virulence genes present in isolated STEC strains. Methods: This research investigated the prevalence of STEC and identified some virulence genes (stx1, stx2, and eaeA) from diarrhoeic and non-diarrhoeic pediatric patients of age 1 to 16 years. A total of 243 stool samples were collected from diarrhoeic and non-diarrhoeic pediatric patients (in ratio 43:200) in four different State Specialist Hospitals in Ondo State, Nigeria. Polymerase chain reaction (PCR) assay was used for detection of Shiga toxinproducing E. coli. The virulence genes (stx1, stx2, and eaeA) were detected by PCR assay. Results: Out of the 243 samples, 163 (67%) were positive for E. coli and specifically 6 of them were positive for E. coli O157 (3.7%). Exactly 50% of the 6 E. coli O157 contained eaeA while all the strains contained Stx1 and Stx2. The results obtained also revealed that 6 strains that were non-O157:H7 STEC also contained Stx1 and four strains contained Stx2 genes. Conclusion:The results obtained from this study revealed that Stx1 and Stx2 genes are of the genes responsible for the virulence of STEC among diarrhoeic and non-diarrhoeic pediatric patients.