Investigating the Diversity of Bacterial Resistance and Virulence in the hybrid Uropathogenic Escherichia coli (UPEC) and Diarrheagenic E. coli (DEC) isolates

Abstract

Escherichia coli is a prevalent commensal bacterial species that also exists in certain pathogenic forms which result in intestinal diseases. Two different pathotypes of E. coli that exist in nature are Extra-intestinal Pathogenic E. coli (ExPEC) and Diarrheagenic E. coli (DEC). Out of the ExPEC species the most common is Uropathogenic E. coli (UPEC). The predominant etiology of Urinary tract infections (UTIs) is linked to UPEC. The existence of complex pathotypes of E. coli can be related to the evolution of new hybrid pathotypes of ExPEC and DEC which might be the result of horizontal gene transfer of transferable genetic fragments. In the current study we have isolated and characterized 100 UPEC isolates for their phylogeny, antibiotic resistance, virulence factors, virulence associated genes (VAGs) and their pathogenic nature. In addition to this we have also detected DEC genetic markers in the UPEC isolates. Most of the isolates were assigned to Phylogroup B2 (38%) and A (28%). The isolates had a high antibiotic resistance profile, where 96% of the strains were resistant to multiple drugs thereby, considered as multiple drug resistant (MDR) strains. Isolates were highly resistant to macrolides (100%) followed by Ampicillin (95%) and Amoxicillin (80%). A large portion of isolates was resistant to different fluoroquinolones. Among the tested isolates, 51% of the isolates also tested for Extended Spectrum β-lactamases. The most common VAG detected in the isolates was fimH it was present in 95% of the isolates. Out of the 100 isolates in our study 15 showed hybrid genetic markers. The hybrid strains contained genetic markers from three DEC pathotypes i.e. Enteropathogenic E. coli (EPEC), Enterohemorrhagic E. coli (EHEC), Enteroggregative E. coli (EAEC). Among the 15 strains there were 5 UPEC/aEPEC/EHEC, 4 UPEC/EHEC, 3 UPEC/aEPEC, 2 UPEC/EAEC and 1 UPEC/tEPEC/EHEC isolates. The 15 hybrid isolates were MDR in nature and the emergence of these MDR hybrid pathotypes poses a new danger in the field of microbiology. There is need to monitor and study these pathotypes to enable us to deal with them in an outbreak.