The Occurrence of blaCTX-M-15 extended-spectrum β-lactamase Among Clinical Isolates of Klebsiella pneumoniae in Khorramabad, Iran.

OBJECTIVE

During the recent decade, CTX-M-type enzymes, primarily CTX-M-15 extended- spectrum β-lactamase (ESBL) have strikingly developed throughout the world. The objective of this study was to investigate the frequency of CTX-M-type β-lactamases, as well as blaCTXM- 15 among Klebsiella pneumoniae isolates in Khorramabad, Iran.

METHODS

In this cross-sectional study, 60 isolates of K. pneumoniae were collected from selected teaching hospitals in Khorramabad, Iran. ESBLs producing isolates were identified using phenotypic double-disk synergy test. The presence of blaCTX-M-types, as well as blaCTX-M-15 gene, were investigated by PCR method.

RESULTS

While the highest resistance rates of isolates were found to nalidixic acid (65%) and trimethoprim/sulfamethoxazole (60%) antibiotics, the least resistance was to imipenem (15%). Moreover, 31(51.7%) isolates were resistant to at least three classes of antibiotics and designated as multidrug resistance (MDR). Fifty-two (86.7%) of 60 isolates were ESBLs positive. Thirty-five (58.3%) isolates harbored CTX-M-type β-lactamases, and also 29 (48.3%) isolates carried blaCTX-M-15.

CONCLUSIONS

This study presents the first report on the frequency of blaCTX-M-15 in the west of Iran, so that our results showed ESBL of CTX-M-15 may partly account for hydrolyzing thirdgeneration cephalosporins.