Genotypes and β-Lactamase Gene Carriage in Carbapenem-Resistant Acinetobacter Baumannii Isolated in Moscow

Abstract

The aim of the study was to determine the mechanisms of resistance to carbapenems in Acinetobacter baumannii strains and give their clonal characteristics by multilocus sequence typing. Materia/s and methods. The authors characterized carbapenem-resistant A.baumannii isolates (CRAB) collected from patients in surgical departments and intensive care units at three hospitals in Moscow in 2012-2015. Sensitivity to carbapenems was determined by the Etest method. Identification of sequence types (ST) was carried out by multilocus sequence typing (MLST) using standard Oxford and Pasteur protocols. Detection of β-lactamase genes was performed by PCR. Resu/ts. Among 88 examined CRAB isolates, the Oxford (Oxf) MLST protocol identified 15STs of 3 clonal complexes (CCs), including CC92Oxf (69%), CC109Oxf (1%), CC944Oxf (30%). CC944Oxf was composed of ST944Oxf (n=16) and two newly described single locus variants ST1103Oxf (n=3) and ST1104Oxf (n=7); all three STs were identical to the Pasteur (Pas) MLST protocol ST78. All CC944Oxf/ST78Pas isolates were b/aOXA-72-positive and all but one of them had a b/aCTX_M_115 gene. ST944Oxf was the only ST found in each of the three study hospitals. Conc/usion. Our data demonstrate the predominance of two clonal lineages among Carba-NS A.baumannii. One of them, the uncommon b/aOXA_72/b/aCTX_M_115-positive clone of CC944Oxf/ST78Pas, seems to be endemic in Russia.

Keywords

• acinetobacter baumannii
• acinetobacter baumannii
• antibiotic resistance
• carbapenemase
• mlst
• clonal complex