Prevalence of Metallo-β-Lactamase Genes in Clinical Isolates of Klebsiella pneumoniae in Health Care Centers in Mazandaran Province

Klebsiella pneumoniae is one of the most important causes of opportunistic infections, including lobar pneumonia, urinary tract infection (UTIs), and wound infection. Treatment of disease caused by this bacterium has also become a challenge, as many strains are resistant to all β-lactam antibiotics. Metallo-β-lactamases hydrolyze most β-lactam antibiotics, especially carbapenems, but cannot inactivate monobactams. This study aimed to determine the prevalence of Metallo-β-lactamase genes (blaIMP, blaVIM, and blaNDM) in K. pneumoniae isolated from clinical specimens.

Clinical samples were collected from hospitals of Mazandaran province. Among 500 clinical samples collected, only 40 Klebsiella pneumoniae isolates were detected by culture and biochemical tests. Antimicrobial susceptibility testing was performed on all isolates by the Kirby-Bauer method. The polymerase chain reaction (PCR) technique was used for the identification of blaIMP, blaVIM, and blaNDM genes.

Antibiogram by disk diffusion method showed that 21 (52%) and 19 (48%) isolates were classified as imipenem resistant and sensitive, respectively. Of all the samples, 30 (75%), 7 (17.5%), and 36 (90%) contained blaVIM, blaIMP, and blaNDM genes, respectively. The co-existence of the blaVIM and blaNDM genes was observed in 22 (55%) isolates. The presence of both blaIMP and blaNDM genes was confirmed in 2 (5%) of the isolates. Four isolates (10%) had blaNDM, blaIMP, and blaVIM genes simultaneously, but none of these genes were present in one isolate (2.5%).

This study showed that the prevalence of metallo-β-lactamase genes in K. pneumoniae isolated from clinical specimens is very high, so it is recommended that physicians treat patients based on phenotypic and genotypic characteristics.