investigation of oxa-23, oxa-24, oxa-40, oxa-51, and oxa-58 genes in carbapenem-resistant escherichia coli and klebsiella pneumoniaeisolates from patients with urinary tract infections

Background: escherichia coli and klebsiella pneumoniae are frequently responsible for urinary tract infections (utis). the high rate of carbapenem resistance in enterobacteriaceae has become a global therapeutic concern. objectives: the study investigated oxa-23, oxa-24, oxa-40, oxa-51, and oxa-58 genes in uropathogenic e. coli and k. pneumoniae isolates. methods: we isolated 500 uropathogenic isolates of e. coli and k. pneumoniae from patients at milad hospital, tehran, iran. antibiotic susceptibility testing was performed using a strip-test method, and the carbapenem-nonsusceptoble isolates were confirmed with an automated antibiotic sensitivity testing system. the oxa genes were determined by multiplex pcr. molecular typing was performed by multilocus variable-number tandem repeat (vntr) analysis (mlva). results: out of 500 isolates, 40 (8%) 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-insensitive e. coli and k. pneumoniae isolates carried a betalactamase- producing gene associated with the oxa-23-like group. finally, e. coli and k. pneumoniae isolates were divided into two and three mlva patterns, respectively. conclusions: this is the first report of oxa-51, 58, and 24 carbapenemases in clinical isolates of e. coli and k. pneumoniae from uti patients in iran. significant differences were seen in oxa-51, 58, and 24 genes between carbapenem-insensitive and carbapenemsensitive e. coli and k. pneumoniae isolates. molecular typing suggested the vertical transmission of resistance genes.