چكيده لاتين :
Background and objective: Acinetobacter spp., particularly A.baumannii, are important opportunistic pathogens that can cause variety of nosocomial infections. A.baumannii is noted for its intrinsic resistance to antibiotics and for its ability to acquire genes encoding resistance determinants. One of the mechanisms of resistance in this pathogen is the expression of active efflux pumps. This study was designed to investigate the resistance of A.baumannii to common therapeutic antibiotics and the role of efflux pump in resistance of clinical strains.
Materials and methods: During 9 months 65 isolates of Acinetobacter were collected from different clinical samples, burns, sputum, bone marrow, blood and urine. Biochemical tests were used for identification of Acinetobacter species. Drug susceptibility test for 12 antibiotics was used by Kirby-Bauer disc diffusion method and then the MIC of 6 antibiotics was determined by the microdilusion method. Subsequently, to show that the high resistance in 20 multidrug resistant strains which showed resistance to more than 10 of these antibiotics depends on proton gradient efflux pump, MICs were also measured in presence and absence of CCCP, using microdilution method.
Results: A.baumannii was identified as the only Acinetobacter species and most of them were known as multidrug resistant (MDR) strains. Results of MIC for ceftazidime, gentamicin, amikacin, cefepime, ciprofloxacin and ofloxacin were more than 256, 64, 64, 32, 16 and 8 fig/ml, respectively. CCCP decreased the level of MICs at least in 1 dilution.
Conclusion: A.baumannii strains exhibits high resistance to a wide range of therapeutic antibiotics. Reduction in the level of MICs in presence of efflux pump inhibitor indicates the possibility of the presence of proton gradient-efflux pump(s) and their role in increasing of resistance in these clinical isolates.
