Molecular characteristics and antibiotic resistance of Acinetobacter spp ; predominance of blaOXA-51 and blaVIM, isolates from patients in Bosnia and Herzegovina

Acinetobacter spp. is an important opportunistic bacterial pathogen responsible for serious infections in the hospital environment. Objectives were to determine the antibiotic susceptibility and to characterize carbapenem-resistance mechanisms of 24 (19 in- and five outpatient) Acinetobacter spp. isolates collected during Decembar 2009 to May 2010 in Bosnia and Herzegovina were investigated. Susceptibility testing was performed by disc-diffusion (DD) and broth microdilution method. The modified Hodge and combined disc test with EDTA with phenylboronic acid were used to screen for carbapenemase production. Production of ESBLs was determined by double-disc synergy test. Ten (52.6%) of the in-and three (60.0%) of outpatient isolates were produced ESBL, MBL or oxacillinases. More than 50% of the isolates showed multidrug-resistance. Resistance rates to gentamicin and ciprofloxacin of the in-and outpatients were 80.0% and 60.0%, and 75.0% and 25.0%, respectively. MICs of carbapenems for resistant isolates ranged from 32->256 g/mL. Six (out of 10) of the in- and one (out of 3) outpatient imipenem-resistant strains were possessed blaOXA-51, as well as blaVIM. Three (out of 10) of the in- and one outpatient isolates possessing blaOXA-51 and blaVIM additionally produced other beta-lactamases (TEM, CTX-M, AmpC, OXA-1).None of the in- and outpatient isolates were positive for other carbapenemases, especially acquired oxacillinases (blaOXA-23, blaOXA-24, blaOXA-58, blaOXA-143) A predominance of blaOXA-51 was noticed with high prevalence of imipenem resistance. Presence of blaOXA-51 and blaVIM presents an emerging threat in imipenem-resistant Acinetobacter spp. from Bosnia and Herzegovina.