Iranian Journal of Medical Microbiology

Background and Aim: According to numerous reports of infections caused by spectrum beta lactamases (ESBLs) producing Acinetobacter baumannii in our country in recent years, this study was performed to define the antibiotic susceptibility patterns and detect the prevalence PER  and VEB beta-lactamase genes among  A.baumannii isolated from patients in Tehran by PCR.

Materials and Methods: 100 A.baumannii clinical isolates collected from various hospitals in Tehran during a year, using special culture media and biochemical tests were identified. The antibiograms of the isolates against 11 antibiotics by disk diffusion method (Disk diffusion) according to Clinical and Laboratory Standards Institute (CLSI) guidelines was performed. Then minimum inhibitory concentrations (MIC) was determined for cefepime and ceftazidime and for the identification of ESBL-producing strains was used in combination disk method, and finally to assess the prevalence of PER and VEB beta-lactamase genes using specific primers PCR was performed.

Results: Antibiograms results showed that the greatest resistance to the antibiotics amikacin, cefepime, and less resistance to polymyxin B were obtained. Rates of multi-drug resistant strains of about 70% was achieved. Of the isolates studied, the MIC of ceftazidime in 84% and for cefepime in 91% were ≥ 128 μg/ml. The results of the combined-disk test demonstrated that 20% of samples were ESBL positive. The PCR results showed that 47% and 32% of our isolates had PER and VEB genes respectively.

Conclusions: Regarding to existence of PER and VEB genes in this bacterium and possibility of transformation of these genes to the other bacteria, reconsideration in antibiotics consumption patterns and more attention to nosocomial infections control criteria are inevitable.