GENETIC PROFILE OF CARBAPENEM-RESISTANT ACINETOBACTER BAUMANNII STRAINS

The purpose of the research: the molecular genetic characteristic of A. baumannii carbapenem-resistant strains, including clonal affiliation, resistome and virulome pattern analysis, description of genetic environment resistance determinants, comparative genetic analysis, and assessment of phylogenetic relationships are presented in the work. The studied A. baumannii strains belonged to sequence types ST2(Pas)/ST2062.2063(Oxf)(n = 5) and ST78(Pas)/ST1757(Oxf )(n = 2). The nucleotide sequences of the studied A. baumannii ST2Pas/ST2062.2063(Oxf )strains were grouped into a single cluster according to phylogenetic analysis. And the sequences of the A. baumannii ST78Pas/ST1757(Oxf) strains were combined with the nucleotide sequence of the A. baumannii AbCTX5 strain, isolated in France in 2015. The presence of intrinsic (OXA51-like) and acquired carbapenemases genes was shown in A. baumannii strains. In particular, blaOXA-23 are identified in members of ST2(Pas)/ST2062.2063(Oxf), and in A. baumannii ST78(Pas )/ST1757(Oxf) strains - blaOXA-72 as part of the plasmid DNA. The A. baumannii ST78(Pas )strains possessed additional extended-spectrum beta-lactamase genes. & Tcy;he CTX-M-115 cephalosporinase gene are present in both strains, and the A. baumannii strain NNAb_2023.3 has the blaCARB-16 gene. Most A. baumannii strains are characterized by the presence of acquired genes for enzymatic modification of macrolides (mph(E), msr(E)), chloramphenicols (catB8), aminoglycosides (aadA, aph(3')'-Ib, aph(6)-Id, aac(6)'-Ib, aph(3)'-Ia, armA). A comparative analysis showed that in A. baumannii ST2Pas/ST2062.2063(Oxf )strains the resistance determinants to macrolides and aminoglycosides are located in the Tn6279-like transposon, and the aminoglycosidases genes aph(3')'-Ib, aph(6)-Id are associated with the IS91-like mobile element. In A. baumannii ST78(Pas)/ST1757(Oxf )strains, resistance genes to aminoglycosides, macrolides, sulfonamides, and beta-lactamase genes are grouped in a region from 60 to 80 Kb long between the glmSand hutC genes. The presence of mutations in the gyrA andparCgenes associated with resistance to fluoroquinolones were characterized in all A. baumannii strains. Thus, new knowledge about the genetic profile of carbapenem-resistant A. baumannii strains representing epidemically significant international clonal lineage has been obtained.