Successful international clones of blaCTX-M-15–producing Klebsiella pneumoniae with coexpression of plasmid-mediated quinolone resistance (PMQR) determinants in Tehran hospitals

• We characterize extended-spectrum β-lactamase–producing K. pneumoniae from Iran.
• CTX-M was the dominating genotype, followed by SHV-ESBLs.
• Other plasmid-encoded resistance genes were frequently found.
• The successful clone sequence type 16 was described for the first time in Iran.
• The pefloxacin disk was used for detection of fluoroquinolone resistance.

The dissemination of plasmid-mediated multidrug resistance in Enterobacteriaceae is a major public health concern. We investigated the prevalence of plasmid-mediated quinolone resistance (PMQR), 16S rRNA methylases, CTX-M, and acquired AmpC enzymes in ESBL-producing Klebsiella pneumoniae (n = 40) from Tehran hospitals. Plasmid replicon typing, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were carried out for typing. CTX-M group 1 (confirmed as blaCTX-M-15 in selected isolates) was found in 35/40 isolates. Thirty-two isolates hosted PMQR genes. Twenty isolates featured aac(6′)-Ib-CR only; 9 isolates had aac(6′)-Ib-CR and qnrB; 2 isolates had aac(6′)-Ib-CR and qnrS; and 1 isolate had aac(6′)-Ib-CR, qnrS, and qepA. The 16S rRNA methylase RmtB was found in 1 isolate; and acquired AmpC enzymes, in 6 isolates. PFGE detected 7 pulsotypes, the largest corresponded to sequence type 16. The successful clone ST101 was also found. The emergence of successful clones of K. pneumoniae in Tehran hospitals is concerning.