Background: The increasing pattern of Multi-Drug Resistant (MDR) bacteria has limited therapeutic options especially for nosocomial isolates of Klebsiella pneumoniae. Therefore, the aim of this study was the molecular detection of 16S rRNA methylase and blaCTX-M-15 among K. pneumoniae strains isolated from hospitalized patients in Mofid, Imam Hossein and Taleghani hospitals.

Materials and Methods:This study was done with 110 K.pneumoniae isolated of hospitals in Tehran, Iran. Antibiotic susceptibility tests were carried out by Kirby-Bauer disc diffusion and broth microdilution methods according to CLSI guidelines. ESBL, AmpC and KPC enzymes were detected by CDDT and MHT methods and the armA, rmtB, rmtC, rmtD and blaCTX-M-15 genes were detected by PCR and sequencing techniques. Typing of antibiotic resistance isolates was carried out by PFGE technique.

Results: In this study, Fosfomycin, colistin and tigecycline were more active than other antibiotics. Among the 110 K. pneumoniae strains, 60(54.5%), 33(30%) and 5(4.5%) were ESBL, Amp-C and KPC positive, respectively. The existence of blaCTX-M-15, armA and rmtC was detected in 40(36.3%), 15 (13.6%) and 2 (1.8%) respectively. Of 15 representative armA-producing K. pneumoniae isolates analyzed by PFGE, 9 different pulsotypes (PF1–9) were identified with Dice coefficients of &ge90% similarity.

Conclusions: High-level aminoglycoside resistance in human pathogens result of 16S rRNA methylases is one of the serious concerns in Iran.