Clinical Microbiology and Antimicrobial Chemotherapy. 2014; 16(4):266-272
Acinetobacter baumannii and related species of the Acinetobacter calcoaceticus-baumannii complex are the common and one of the most difficult-to-treat nosocomial pathogens. In this paper, we report the data on antimicrobial susceptibility of 252 isolates of Acinetobacter spp. collected in 25 hospitals of 18 cities of Russia in 2011–2012 as part of the national multicenter surveillance study on antimicrobial resistance of nosocomial pathogens, «MARATHON». Acinetobacter spp. and, specifically, A. baumannii isolates comprised, respectively, 14.8% and 13.9% of all bacterial nosocomial isolates. The non-susceptibility rates to carbapenems were: 67.5% to meropenem and 96.0% to imipenem that is, accordingly, 28.9% and 90.9% higher than they were in 2006–2007. The genes for acquired molecular class D carbapenemases were detected in 46.8% of A. baumannii isolates. Those included the genes for OXA-40-like (38,0%), OXA-23-like (4,6%) и OXA-58-like (4,2%) enzymes. One A. pittii isolate carried the gene for NDM-type metallo-b-lactamase. Most of the isolates were insusceptible to fluoroquinolones: ciprofloxacin and levofloxacin (92.1%), to aminoglycosides: gentamicin (85.3%), amikacin (86.9%) and tobramycin (64.7%), and to trimethoprim-sulfamethoxazole (79.4%). Colistin had the highest in vitro activity with resistance rate being as low as 1.6%. A total of 55.6% and 63.1% had the MICs of tigecycline and sulbactam exceeding the epidemiological cut-off values of 1 mg/l and 4 mg/l, respectively. Notably, 86.9% of the isolates were categorised as extensively drug-resistant (XDR) and 1.2% — as pan-drug-resistant (PDR).