Molecular characterization and prevalence of shiga toxigenic E. Coli isolated from children under 5 years in the Molecular Laboratory, Makerere University

Abstract

Background: Foodborne infections are a public health concern Worldwide. Shiga toxin–producing Escherichia coli (STEC) is one often most important strain of threat in the food system particularly in children where diarrheal diseases are more rampant. Phenotypic characterization of E. coli was reported to limit proper identification yet rapid spread of resistant STEC serotypes was fast becoming a threat to public health and increased morbidity. It was not known still the prevalence of Shiga toxin-producing Escherichia coli (STEC) and distribution of its genotypes from E. coli isolated from children under five years in the molecular laboratory, Makerere University. Methods: In a descriptive cross-sectional study of molecular characterization and prevalence of shiga toxigenic E. coli isolated from children under five years in the molecular laboratory, Makerere University, the stored E. coli isolates were subcultured onto MacConkey agar and incubated at 370 C for 24 hours to obtain fresh bacterial growth. Pure colonies were then obtained by sub-culturing a single colony of the confirmed isolate on Nutrient agar. DNA was extracted and conventional PCR was used to detect the presence of shiga toxin 1 and 2 virulence genes in the E. coli isolates. Results: A total of 51E. coli isolates from children under five years were used and of these, 4 had STEC, representing a prevalence of 8%. The shiga toxin genotypes had three patterns of distribution including; stx1 (50%), stx2 (25%) and stx1 + stx2 (25%) indicating that some STEC isolates had both stx1 and stx2in combination while others had one of the two. This study did not establish why this kind of trend happened. The findings generally concur with similar studies documented elsewhere. Conclusion: There is a significant prevalence of STEC among E. coli cases. Also, stx1 is more prevalent than stx2 and stx1 + stx2 genotypes. The use of polymerase chain reaction assay should aid quick detection of this virulent pathotype and help curb the severe epidemic of human diseases associated with STEC infections.