High Prevalence of Metallo-β-Lactamase-Producing Acinetobacter baumannii in a Teaching Hospital in Tabriz, Iran

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Metallo-beta-lactamase (MBL)-producing Acinetobacter baumannii has become a growing therapeutic concern worldwide. The aims of this study were to evaluate the antimicrobial susceptibility of A. baumannii isolates and to determine the prevalence of MBL genes among carbapenem non-susceptible isolates. During a period of 16 months (March 2008-June 2009), 100 isolates of A. baumannii were collected from different clinical specimens of inpatients admitted to the largest teaching hospital in the northwest of Iran. All isolates were tested for antimicrobial susceptibility by Kirby-Bauer disk diffusion method. Carbapenem non-susceptible isolates were further screened for production of MBL by Etest and were then subjected to PCR for detection of MBL genes of types bla_IMP and bla_VIM. Among 63 carbapenem (imipenem and meropenem) non-susceptible isolates of A. baumannii, 31 (49%) were found to be MBL producers. Of 31 MBL-producing isolates, 19 (61%) carried the bla_IMP gene and 9 (29%) carried the bla_VIM gene. All MBL-producing isolates were multidrug resistant. This is the first report of IMP and VIM types among MBL-producing A. baumannii in Iran.