First report of class 1 and class 2 integrons in multidrug-resistant Klebsiella pneumoniae isolates from northwest Iran.

We investigated the prevalence of multidrug resistance, production of extended-spectrum β-lactamases (ESBLs), and presence of class 1 and 2 integrons in 150 clinical isolates of Klebsiella pneumoniae from northwest Iran by performing phenotypic confirmatory tests and polymerase chain reaction (PCR) analysis. Of the 150 isolates, 149 (99.3%) were multidrug resistant (MDR). Of the MDR isolates, 124 (83.2%) were ESBL positive. The results of the PCR analysis showed that 117 (78.5%) and 20 (13.4%) MDR K. pneumoniae isolates carried intI1 and intI2, respectively, and 16 (10.7%) MDR K. pneumoniae isolates contained the integrase genes of both class 1 and class 2. Resistance of the isolates to gentamicin, tetracycline, ceftazidime, cephalothin, chloramphenicol, and nalidixic acid was observed to be significantly associated with the presence of class 1 integrons; however, the resistance to tetracycline was observed to be associated with the presence of class 2 integrons alone. This study showed that integrons are widely prevalent in the clinical isolates of K. pneumoniae from northwest Iran, and that they may be playing an important role in attributing multidrug resistance to the clinical K. pneumoniae isolates. To the best of our knowledge, this is the first report showing the presence of class 1 and class 2 integrons in MDR K. pneumoniae isolates from clinical settings in northwest Iran.