Objective: Pseudomonas aeruginosa is an important nosocomial pathogen frequently resistant to “antipseudomonal” drugs, including carbapenems. Treatment regimes for the eradication of P. aeruginosa infections are becoming increasingly limited. This study was conducted to determine the rate of resistance of P. aeruginosa strains to various antibiotics and to investigate the presence of metallo-beta-lactamases (MBLs) in the imipenem resistant strains using a phenotypic method.

Materials and Methods: The antibiotic susceptibilities of a total of 100 P. aeruginosa strains isolated from various clinical specimens, were determined by Kirby-Bauer disk diffusion method according to the CLSI guidelines. Combined disc (IMP-EDTA) test method was used for the presence of MBL in imipenem-resistant and intermediate strains.

Results: The antibiotic resistant rates determined for various antibiotics as follows: imipenem (25%), cefepime (14%), ceftazidime (19%), piperacillin/tazobactam (10%), aztreonam (24%), ciprofloxacin (11%), tobramicin (6%) and amikacin (5%). Metallo-beta-lactamase production was detected in 80% of the imipenem resistant and intermediate P. aeruginosa strains.

Conclusion: In our study, the MBL positivity rates obtained by the combined disc test method is consistent with other studies. MBL presence should be investigated in imipenem-resistant strains to prevent the spread of resistance.