analysis of carbapenemases genes of carbapenem-resistant klebsiella pneumoniae isolated from tehran heart center

Background and objectives: emerging of carbapenem-resistant klebsiella pneumoniae (crkp) is one of the major con- cerns among healthcare systems. this study aimed to investigate the antibiotic susceptibility pattern and carbapenemase genes of carbapenemase-producing k. pneumoniae isolates obtained from iranian hospitalized patients.materials and methods: this study was performed on 71 crkp strains isolated from different clinical specimens collectedin tehran heart center (tehran, iran). a modified hodge test (mht) was done for the detection of carbapenemase-producingk. pneumoniae. the presence of blamethod.kpc, blavim, blaimp, bla, and blaoxa-48-type carbapenemases was evaluated by the pcrresults: we identified 8.82% (71/805) of k. pneumoniae isolates as crkp by mht test. the antibiotic susceptibility indi- cated that all isolates were resistant to imipenem, meropenem, cefotaxime, ceftazidime, cefepime, ceftriaxone, cephalothin, ciprofloxacin, and augmentin, and then mostly resistant to aztreonam, cefoxitin, gentamicin, and trimethoprim/sulfamethox- azole with 98.6%, 98.6%, 97.2%, and 94.4%, respectively. the lowest resistance was related to amikacin with 46.5% (33/71 isolates). the level of imipenem mic for all carbapenem-resistant isolates was estimated ≥32 μg/ml. among positive iso-lates for carbapenemase genes, the most frequent gene was bla. it was found in 48 (67.6%) isolates followed by blavimin 28 (39.4%) isolates. blaimp,bla, and blakpcgenes were identified in 19 (26.8%), 13 (18.3%) and 5 (7.0%) isolates,respectively. these genes were not detected in nine isolates.conclusion: the relatively high frequency of some carbapenemase genes suggests major concern about the emergence of isolates containing carbapenem resistance genes as a potential health threat.