Molecular epidemiology of Escherichia coli sequence type 131 and its H30/H30-Rx subclones recovered from extra-intestinal infections: first report of OXA-48 producing ST131 clone from Iran

Multidrug-resistant (MDR) O25b-ST131 clone of Escherichia coli is well established as a significant cause of extra-intestinal infections worldwide. However, there have been no studies about the prevalence of ST131 and its H30/H30Rx subclones from Iran. The prevalence of ST131 was 29.8% among phylogroups B2, D, and F of E.coli isolates recovered from extra-intestinal infections. Fifty-seven (90.4%) and six (9.6%) of isolates belonged to serogroups O25b and O16 respectively, and exhibited high rates of MDR (98.4% and 83.3%) and extended spectrum beta-lactamase (ESBL) production (96.8% and 83.3%). The majority (56/57, 98.2%) of O25b isolates belonged to H30 lineage; of those, 24 isolates (42.8%) belonged to H30-Rx subclone. O16-ST131 isolates were H30-negative. The resistance rate values of O16-ST131subgroup were lower for fluoroquinolones/aminoglycosides and higher for carbapenems, cephalosporins, beta-lactam/beta-lactamase inhibitors and trimethoprim/sulfamethoxazole, as compared to O25b-ST131 isolates. Among H30 sub lineage and in comparison with non-Rx isolates, H30-Rx subclone showed higher resistance score and virulence genes (papA and papC), and was also associated with CTX-M group 1. bla(OXA-48) carbapenemase was detected in seven O25b and one O16 isolates; of those, one O25b-ST131 isolate was carbapenem-susceptible. The ST131 isolates comprised 15 'enterobacterial repetitive intergenic consensus' (ERIC) clusters, and O16 isolates remained distributed in five groups in cluster with O25b-ST131 isolates. In conclusion, this is the first report of the presence of MDR, bla(OXA-48)/CTX-M-positive O25b/O16-ST131 isolates in Iran. Contrary to lower prevalence of O16-ST131 subgroup, higher resistance rates to beta-lactam antibiotics may indicate the importance of this subgroup in the spread of MDR E.coli isolates.