Prevalence of metallo-β-lactamase among imipenem-resistant Acinetobacter spp. isolated from selected hospitals in Karaj (2010)

Imipenem-resistant Acinetobacter spp. resulting from metallo-β-lactamase (MBLs)-producing strains have been reported to be among important causes of nosocomial infections and of serious therapeutic problem worldwide. To determine the prevalence of metallo-β-lactamase among imipenem-resistant Acinetobacter isolates based on phenotypic methods. This was an descriptive study in which 140 clinical isolates of Acinetobacter spp. were initially tested for imipenem susceptibility and later for metallo-β-lactamase production using combined disk diffusion, double disk synergy test, and Hodge test during 2010. Antibiotic susceptibility of positive metallo-β-lactamase isolates were further evaluated by disk diffusion technique using CLSI methodology. Of 140 isolates, 29 (20.7%) were imipenem-resistant Acinetobacter. Positive phonetypic test for metallo-β-lactamase was 24 (17.1%). The result of this study is indicative of growing number of nosocomial infections associated with multidrug-resistant Acinetobacter spp. in this region leading to difficulties in antibiotic therapy.