New Delhi metallo-β-lactamase-1- producing Klebsiella pneumoniae isolates in hospitalized patients in Kashan, Iran

New Delhi metallo-ß-lactamase (NDM) is a newly emerging metallo-ß-lactamases, which can destroy all β-lactams including carbapenems. Therefore, this study aimed at evaluating New Delhi metallo-ß-lactamase-1–production in clinical isolates of Klebsiella pneumoniae in Kashan, Iran.
In a cross-sectional study, 181 K. pneumoniae isolates were collected from clinical samples of patients, who referred to Shahid Beheshi hospital in Kashan during November 2013 and October 2014. Antimicrobial susceptibility patterns were determined using disk diffusion method, according to CLSI guidelines. Metallo-ß-lactamase (MBL) production was identified among imipenem- resistant K. pneumoniae isolates using imipenem-EDTA double disk synergy test (EDTA-IMP DDST). PCR method and sequencing were used to detect integron Class 1 and blaNDM-1 gene. Statistical analyses were performed using SPSS software Version 16.
Of the 181 K. pneumoniae isolates, 36 (19.9 %) were imipenem-resistant strains. A total of 28 out of 36 (77.7%) imipenem- resistant K. pneumoniae isolates were identified as MBL producer strains. Also, 150 (82.9%) K. pneumoniae isolates carried intI1 gene, and 20 (11.1%) K. pneumoniae isolates harbored blaNDM-1 gene.
Our study revealed a high frequency of MBL production and the presence of blaNDM-1 among K. pneumoniae strains, especially among hospitalized patients, which is alarming. Moreover, the presence of Class 1 integrons in all multi-drug resistant K. pneumoniae isolates highlights the risk of rapid spread of the resistance genes, especially in clinical settings.