Determination of antibiotic resistance pattern and frequency of carbapenemase-producing genes in Acinetobacter baumannii isolated from patients admitted to Tehran Teaching Hospital

The rapid emergence and spread of carbapenem resistant Acanthobacter baumannii has been reported worldwide. The aim of this study was to determine the pattern of antibiotic resistance and the frequency of carbapenemase-producing genes in Acinetobacter baumannii isolated from patients admitted to Tehran Teaching Hospital.

In the present study, 99 clinical isolates of Acinetobacter baumannii collected from a teaching hospital in Tehran were confirmed by biochemical tests and PCR. The pattern of antibiotic susceptibility was determined by disk diffusion and E-test. The frequency of carbapenemase producing genes was determined by PCR.

The highest and lowest resistance were observed to ciprofloxacin (100%) and minocycline (21.2%) respectively. Also 97 strains (97.97%) showed MDR resistance pattern. In determining the minimum inhibitory concentration (MIC) of Acinetobacter baumannii isolates for imipenem antibiotic by E-test, 93.9% of the isolates were resistant and the MIC of imipenem for them was more than 8 μg / ml. In the study of the frequency of carbapenemase producing genes using PCR; The blaVIM gene had the highest frequency (94.9%) and blaOXA-58, blaOXA-143, blaKPC and bla IMP were not found in any of the isolates.

The results of the present study show that most isolates have been resistant to clinically important beta-lactam antibiotics used in the treatment of Acinetobacter baumannii infections. Further studies on the rational administration of the drug in the treatment of Acinetobacter baumannii  infections are suggested.