The prevalence of carbapenem resistance among Pseudomonas aeruginosa has been increasing worlwide. Carbapenem resistance is mainly due to either reduced level of drug accumulation or increased expression levels of the pump efflux. Recently, the resistance was determined to be occasionally due to the production of metallo-beta-lactamases (MBL). From June 2006 to January 2010, 58 imipenem and meropenem resistant, non-recurring isolates of P. aeruginosa from clinical samples of intensive care units patient of the Training Hospital of Gulhane Military Medical Faculty, Turkey were included in the study. Identification and antimicrobial susceptibility test of the isolates were performed by using the conventional methods and PhoenixTM 100 Instrument (Becton Dickinson, USA). Modified Hodge test (MHT), double-disk synergy (DDS) method, combined disk test (CDT) and MBL E-test were used to screen MBLs. MHT was negative for all isolates. None of these isolates showed MBL activity by DDS test, CDT and MBL E-test methods. For this reason, it is thought to be that the carbapenem resistance was not due to metallo-beta-lactamase in our strains. It should be considered that, the small sample size could lead this result. Further studies are needed to detect the other mechanism of resistance against carbapenems.
Keywords: Metallo-beta-lactamases, P. aeruginosa, double-disc synergy test, MBL E-test, combined disk test
