Analysis of diarrheagenic potential of uropathogenic Escherichia coli isolates in Dhaka, Bangladesh

Introduction: Uropathogenic Escherichia coli (UPEC) strains are chiefly responsible for urinary tract infections (UTIs). The aim of the study was to observe the virulence properties of UPEC and to determine whether they carry virulence properties of diarrheagenic E. coli. Methodology: Seventy-one pure cultures were collected from UTI patients. After biochemical identification, 56 UPEC strains were examined for biofilm formation capability, hemolytic activity, presence of UTI-associated virulence genes (papC, fim1, afa, sfa) and diarrhea-associated virulence genes (estA, eltB, vt1, vt2, eaeA, aatA, ial, bfpA) by multiplex polymerase chain reaction (PCR) assay. Results: Among the 56 UPEC strains, 21 showed biofilm formation ability, and only 5 showed beta-hemolytic activity. In multiplex PCR, 42% were found positive for papC gene, 27% were fim1 positive, 11% were afa positive, and none were sfa positive. The diarrheagenic genes found were vt2, ial, estA, eltB, bfpA, and aatA, but only in seven isolates. Of these isolates, two were positive for estA and one was positive for eltB, characteristic genes also found in enterotoxigenic E. coli. One carried vt2, a gene characteristically found in enterohemorrhagic E. coli. Another one was characterized as enteropathogenic E. coli (EPEC), as it was carrying the EPEC gene bfpA. Another isolate was positive for ial, the characteristic gene found in enteroinvasive E. coli, and one isolate was found to harbor the aatA gene, a gene found in all enteroaggregative E. coli. Conclusions: This study revealed that most UPEC strains were unique to uropathogenic virulence properties, and very few carried diarrheagenic properties.