Occurrence of SHV, TEM and CTX-M β-Lactamase Genes Among Enteropathogenic Escherichia coli Strains Isolated From Children With Diarrhea

BACKGROUND: Antibiotic resistance is widespread among diarrheagenic Escherichia coli in developing countries, where the overuse of antibiotics is common. Information regarding β-lactamases, especially Extended-Spectrum β-Lactamases (ESBLs) in diarrheagenic pathogens should be considered in clinical management when an optimal treatment is needed. OBJECTIVES: The main objective of this study was to investigate the prevalence of bla(CTX-M), bla(SHV) and bla(TEM) β-lactamase genes among enteropathogenic E. coli (EPEC) isolates in Tehran, Iran. MATERIALS AND METHODS: Stool specimens were collected from children with diarrhea during a 17-month period from 2011 to 2013. Routine biochemical tests were performed for identification of E. coli isolates. The isolates were further examined by PCR for the presence of eae, stx1, stx2 and bfp genes. EPEC isolates have been screened for different β-lactamase genes. Genotyping EPEC isolates harboring bla(CTX-M15) gene was performed through Multi-Locus VNTR Analysis (MLVA). RESULTS: Of 42 EPEC, eight isolates carried the bla(CTX-M1). None of the isolates carried bla(CTX-M2) and bla(CTX-M9). The bla(CTX-M15) variant was identified in all of bla(CTX-M1)-positive isolates. Furthermore, bla(SHV) and bla(TEM) genes were detected in 40.5% (n = 17) and 19% (n = 8) of all EPEC isolates, respectively. No significant association was observed between the existence of bfp gene and presence of those β-lactamase genes (P > 0.05). MLVA analysis revealed high genetic diversity among bla(CTX-M15)-positive isolates. CONCLUSIONS: Our study emphasized the increasing role of ESBL genes, especially bla(CTX-M15) in EPEC isolates.