Carbapenem-nonsusceptible (Carba-NS) Acinetobacter baumannii has emerged as an important cause of nosocomial infections. In the present study, we characterized 91 Carba-NS A. baumannii isolates collected from patients of surgical departments and intensive care units at three hospitals in Moscow in 2012-2015. Multilocus sequence typing (MLST) using the Oxford (Oxf) scheme identified 16 sequence types (STs) of three clonal complexes (CCs), including CC92Oxf (67%), CC109Oxf (1%), CC944Oxf (29%), and the singleton ST1100Oxf (3%). CC944Oxf was composed of ST944Oxf (n = 16) and two of its newly described single locus variants ST1103Oxf (n = 3) and ST1104Oxf (n = 7); all the three STs were identical to the Pasteur (Pas) MLST scheme ST78. All CC944Oxf/ST78Pas isolates were blaOXA-40-like positive and all but one isolate harbored a blaCTX-M-like gene. ST944Oxf was the only ST found in each of the three study hospitals. Biofilm growth capacity was similar among Carba-NS and nonclonal carbapenem-susceptible isolates. Our data demonstrate the predominance of two clonal lineages among Carba-NS A. baumannii. One of these, the uncommon blaOXA-40-like/blaCTX-M-like-positive clone of CC944Oxf/ST78Pas, seems to be endemic in Russia.
Keywords: Acinetobacter baumannii; MLST; biofilm; carbapenem resistance; clone; sequence type.