Background: Acinetobacter spp., as important opportunistic pathogens, have been found to be responsible for an increasing number of nosocomial infections. This study was undertaken to investigate the antimicrobial susceptibility and molecular typing of Iranian isolates of A. baumannii.

Methods: The study was conducted over a period of 19 months in three hospitals in Tehran , Iran . Acinetobacter spp. were isolated from different clinical specimens using standard bacteriological methods. Antimicrobial susceptibility test was performed according to the standard CLSI guideline using 17 antibiotic disks. The AP-PCR fingerprinting was carried out using ARB11 primer. The PCR product was run and visualized in 2% agarose gels and stained with ethidium bromide. The AP-PCR profiles were grouped depending on the patterns of the amplified bands.

Results: Sixty seven strains of Acinetobacter spp. (including 21 A. baumannii and 46 non- A. baumannii) were isolated.

The sources of these isolates were blood, urine, wound, and respiratory tract. A. baumannii isolates were further studied.

Results showed that all A. baumannii isolates were resistant to at least 11 antibiotics tested. AP-PCR analysis of A. baumannii strains resulted in 7 different patterns. The dominant AP-PCR pattern was E (57.1%).
Conclusion: Acinetobacter spp. are still important nosocomial pathogens in the region studied and most of isolates were multi-drug resistant. Our results also indicate that the AP-PCR technique represents a rapid and simple means for typing of A. baumannii.