Determination of extended-spectrum β-lactamase producing and hybrid pathotypes of Escherichia coli isolates from diarrheic samples

Abstract

ObjectiveIntra-intestinal pathogenic and antibiotic resistant strains of Escherichia coli are responsible for mild to severe gastrointestinal lesions mediated by various virulence and resistance factors. This study was undertaken to determine the genes related to the extended-spectrum β-lactamase producing and hybrid pathotypes of E. coli isolates from diarrheic human cases in southeast of Iran. MethodTotally, 467 gastrointestinal patients were considered to collect 467 fecal samples during four years (2016 to 2020). Four pathotypes of E. coli (EPEC, ETEC, EHEC, STEC) were screened for five virulence genes, including eae, stx1, stx2, st, and lt using the conventional PCR method. The detected E. coli pathotypes were subjected to determine phenotypic and genotypic β-lactam resistance properties using disc diffusion method and the conventional PCR, respectively. ResultThe virulence profiling of E. coli isolates showed that from 467 (12.63%) isolates, 59 belonged to the four pathotypes of STEC (30/59; 50.8%), EPEC (11/59; 18.6%), ETEC (8/59; 13.5%), EHEC (5/59; 8.4%) and also three hybrid pathotypes of STEC/ETEC (3/59; 5%), EHEC/ETEC (1/59; 1.6%), and EPEC/ETEC (1/59; 1.6%). The phenotypic antibiotic susceptibility testing showed that from 59 isolates, 23 (38.9%) were identified as the ESBL-producing and 58/59 (98.3%) isolates were positive for at least one of the studied β-lactam genes. ConclusionThis study showed considerable occurrence of the β-lactam resistant diarrheagenic E. coli strains in southeast of Iran. Presence of the hybrid pathotypes detected in this research might potentially lead to more severe intestinal infections. Therefore, there is a need to increase surveillance to reduce the spread of antibiotic-resistant E. coli pathotypes in this region.