Abstract

To determine the prevalence of metallo-β-lactamases (MBLs) in Pseudomonas aeruginosa and to investigate whether MBL genes have spread in MBL-producing isolates. A total of 350 clinical isolates of P. aeruginosa were screened for production of MBL. Antibiotic susceptibility testing was determined by E-test strips. Six MBL genes and class 1 integron were tested by polymerase chain reaction (PCR). Positive MBL genes were subjected to sequencing. Matting out assay was carried out. The resistance rates of 350P. aeruginosa isolates to piperacillin, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, aztreonam, imipenem, and ciprofloxacin were 54, 50.3, 48.3, 45.14, 40.3, 30.57, 38.6 and 36.85%, respectively. The results of MBL screening revealed that 20.57% (72/350) of P. aeruginosa produced MBL. Sixty three (46.46%) of 135 imipenem-resistant isolates were not found to produce MBL. MBL-producing isolates were 100% resistant tob-lactams except aztreonam, which showed resistance rate of 63.88%. Only 20.3 and 5.42% of the MBL-producing isolates were resistant to amikacin and polymyxin B, respectively. PCR and deoxyribonuleic acid (DNA) sequencing investigated revealed that all MBL isolates harbour bla_VIM-2 gene_. High prevalence of imipenem resistant and MBL-producing P. aeruginosa isolates was reported. Imipenem resistance is in increasing and MBL is responsible for 20.57% of the resistance. The bla_VIM-2 is the dominant MBL gene in MBL-producing isolates in Saudi Arabia.

Key words: Carbpenem resistance, Metallo-beta-lactamases, VIM-2, Pseudomonas aeruginosa, Saudi Arabia.