Investigation of OXA-23, OXA-24, OXA-40, OXA-51 and OXA-58 genes among carbapenem-resistance Escherichia coli and Klebsiella pneumoniae isolates in patients with UTI

Urinary Tract Infections (UTI) can depend on many factors such as bacteria, Escherichia coli and Klebsiella pneumoniae in particular. The high rate of carbapenem resistance in Enterobacteriaceae has become a global therapeutic problem.

The aim of this study was the investigation of OXA-23, OXA-24, OXA-40, OXA-51 and OXA-58 genes in uropathogenic isolates of E. coli and K. pneumoniae.

All 500 uropathogenic isolates of E. coli and K. pneumoniae have been segregated from patients at Milad Hospital, Tehran, Iran. Antibiotic susceptibility testing was performed using a strip-test method and the confirmation of carbapenem-resistant isolates were performed using an automated antimicrobial susceptibility testing system. OXA genes were determined by multiplex PCR assay. Moreover, molecular typing of isolates was performed by MLVA.

Out of 500 isolates, 40 (8%) isolates were detected as carbapenem-resistant, including 13 E. coli and 27 K. pneumoniae. All carbapenem-resistant isolates were ESBL-producing and resistant to ceftriaxone, ciprofloxacin, meropenem, ceftazidime and amoxicillin-clavulanate. Moreover, 46.1% and 26% of carbapenem-resistant E. coli and K. pneumoniae isolates had a gene encoding β-lactamase associated with the OXA-23-like group. E.coli and K. pneumoniae isolates were divided into 2 and 3 MLVA patterns, respectively.

This is the first report of OXA-51, 58 and 24 carbapenemases in clinical isolates of E. coli and K. pneumoniae isolated from urinary tract infections in Iran. Significant differences in OXA-51, 58 and 24 genes were found in carbapenem-resistant and carbapenem-susceptible E. coli and K. pneumoniae isolates. Molecular typing of isolates has suggested vertical transmission of resistant genes.