Virulence genotyping of Escherichia coli isolates from diarrheic and urinary tract infections in relation to phylogeny in southeast of Iran

The purpose of this study was to determine the prevalence of virulence genes and phylogenetic groups/subgroups of Escherichia coli (E. coli) isolates from diarrheic and urinary tract infections (UTI) cases in Rigan area, southeast of Iran. One hundred thirty five E. coli were isolated from diarrheic (90 isolates) and urinary tract infections (45 isolates) samples. The confirmed isolates were examined to detect the phylogenetic group/subgroups and a selection of virulence genes including iucD, sfa/focDE, afaIBC, papEF, hly, cnfI and cdtI by PCR. The examined isolates belonged to four phylogenetic groups A (42.2%), B1 (14.1%), B2 (10.4%), and D (33.3%). Among 135 tested bacteria, 62.22% of diarrheic and 30.37% of UTI isolates had at least one of the virulence genes. In the diarrheic isolates iucD (47.77%) was the most prevalent gene. The other genes including sfa/focDE, afaIBC, papEF and cnfI/cdtI genes were detected in 15, 13, 11 and one diarrheic isolates respectively. None of the diarrheic isolates were positive for hly gene. Out of 45 UTI isolates 28.88% were positive for iucD, 13.33% for cnfI, 11.11% for afaIBC, 11.11% for papEF, 6.66% for sfa/focDE and 4.44% for cdtI genes. Several combination patterns of the virulence genes were detected in diarrheic and UTI isolates. In conclusion, the prevalence of virulence genes in diarrheic and UTI isolates differ according to phylogenetic groups, although B2 and D phylotypes have an accumulation of virulence associated genes.