Dissemination of different sequence types lineages harboring blaCTX-M-15 among uropathogenic Escherichia coli in Kerman, Iran

Escherichia coli is one of the most important causes of urinary tract infections (UTIs). The aim of this study was to determine antimicrobial resistance, resistance and virulence genes; phylogenetic groups and identify the epidemiologic features of uropathogenic E. coli (UPEC) isolates by multilocus sequence typing (MLST).

One hundred isolates of E. coli from inpatients with UTIs were collected in Kerman, Iran. Antimicrobial susceptibility testing, ESBLs, AmpC production and biofilm formation were performed by phenotypic methods. Phylogenetic groups, resistance and virulence genes were detected. Molecular typing of isolates was performed by MLST.

In this study, 76% of isolates were multidrug-resistant. The blaCTX-M-15 and blaTEM were the dominant ESBL-encoding gene. Among 63 ciprofloxacin-resistant isolates, the frequency of qnrS (15.8%), qnrB (9.5%), and aac (6’)-Ib (25% ) genes was shown. Fifty-five present of isolates were classified as week biofilm, (14%) moderate biofilm, and (5%) strong. The predominant phylogenetic group was B2 (3) .  The prevalence of virulence genes ranged fimH (93%), iutA (66%), KpsmtII (59%), sat (39%), cnf (28%) and hlyA (27%). According to MLST results, 14 sequence types (ST) including ST-693, ST-90, ST-101, ST-1664, ST-2083, ST-131, ST-4443, ST-744, ST-361, ST-405, ST-922, ST-648, ST-5717and ST-410 were detected, indicating a high degree of genotypic diversity.

We identified a high frequency of the ST131 clonal group among UTIs. These data show an important public health threat, and so further studies to control the dissemination and risk factors for acquisition of the ST131 clonal group and other STs are needed to make effective control.