Phenotypic and genotypic characterization of metallo-β-lactamase producing Pseudomonas aeruginosa isolated from burn patients

Pseudomonas aeruginosa is an opportunistic pathogen associated with many nosocomial infections. This study aimed to detect blaIMP and blaVIM genes and their common subtypes, including bla(IMP-1), bla(IMP-2), bla(VIM-1), and bla(VIM-2,) among imipenem-resistant Pseudomonas aeruginosa strains. In this study, 117 P. aeruginosa strains were isolated from clinical samples of burn wound patients in Velayat hospital, Rasht, Iran, between 2018 and 2019. These isolates were tested for antimicrobial susceptibilities by disk diffusion and Metallo-β-Lactamase (MβL) activity. The polymerase chain reaction (PCR) test was applied to detect MβLs encoding genes in MβL-producing strains. The resistance rates were as follows: Tobramycin (59%), Gentamicin (57%), Piperacillin (52%), Ciprofloxacin (51%), Ceftazidime (32%), and Amikacin (26%). Among 27 (23%) imipenem-resistant isolates, 13 (48%) produced the MβL enzyme. PCR results of imipenem-resistant isolates showed that five and four isolates contained the blaVIM (4 blaVIM1, 2 blaVIM2) and blaIMP (4 blaIMP1, 2 blaIMP2) genes, respectively. In addition some of isolates had more than one gene. In this study, 48% of imipenem-resistant strains produced the MβL enzyme. Therefore, systematic surveillance to detect MβL-producing bacteria and rational prescription and use of carbapenems could be helpful to prevent the spread of carbapenem resistance.