Prevalence of Metallo-β-Lactamases ProducingAcinetobacter baumanniiin a Moroccan Hospital

Objective. To determine the prevalence of metallo beta-lactamases (MBL) among carbapenem resistant strains of Acinetobacter baumannii in our hospital. Methodology. During a period of 12 months (January–December 2010), 47 isolates of Acinetobacter baumannii were collected from different clinical specimens of in-patients. Antimicrobial susceptibility was determined and interpreted using the disk diffusion method according to the Antibiogram Committee of the French Society for Microbiology guidelines. Imipenem nonsusceptible isolates were further screened for production of MBL. Results. All Acinetobacter baumannii’ isolates were resistant to ticarcillin, ticarcilline/clavulanate, piperacillin, piperacillin/tazobactam, gentamicin, tobramycin, and ciprofloxacin, except an isolate that was sensitive to ceftazidime and cefepime. In addition to that, amikacin and trimethoprim/sulfamethoxazole were, respectively, sensitive by 59.5% and 53%. Among 57,4% (27/47) imipenem non-susceptible isolates of Acinetobacter baumannii, 74% (20/27) were found to be MBL producers. Conclusion. Although the rate of imipenem non-susceptible isolates of Acinetobacter baumanni seems to remain stable in 2005 (57%) and 2010 (57,5%), the prevalence of MBL producer strain is increasing (38% in 2005 versus 75% in 2010). The findings strongly suggest that there is a need to track the detection of MBL producers; moreover, a judicious use of carbapenems is necessary to prevent further spread of these organisms.