Biofilm-forming ability of prevalent clonal strains of carbapenem resistant Acinetobacter baumannii / 中国感染与化疗杂志

ABSTRACT

Objective To analyze the homology, biofilm-forming ability, and risk factors of prevalent A, B, C clones(carrying blaOXA-23 and blaOXA-51 genes mostly) of carbapenem-resistant Acinetobacter baumannii (CRAB) relative to carbapenemsusceptible Acinetobacter baumannii (CSAB). Methods A total of 87 prevalent A, B, C clones of CRAB and CSAB strains were collected from the First Affiliated Hospital of Chongqing Medical University. Multilocus sequence typing (MLST) was used for homologyanalysis of clone A, B, C strains. Biofilm-forming ability of CRAB and CSAB was measured quantitatively via crystal violet staining. Results Clone A was measured to be homologous type of ST238, while clones B and C were ST238 type. In general, CRAB prevalent clones showed weaker biofilm-forming ability than CSAB strains (0.470±0.301 versus 0.913±0.626, P＜0.05). CRAB clones A, B, and C varied in ability of biofilm formation. Clone A had comparative biofilm-forming ability to clone C (P=0.432). Both clone A and C were weaker than clone B in biofilm-forming ability (both P＜0.001). Biofilm-forming ability was not associated with blaOXA-23 or blaOXA-51 genes in CRAB strains (both P＞0.05). Conclusions Prevalent CRAB clone A, B, C are derived from the same origin. We are the first to report the prevalence of ST238 and the homologous types in a hospital. Biofilm-forming ability is negatively correlated with carbapenem resistance of Acinetobacter baumannii, which suggests that clone prevalence is mainly related to antibiotic resistance acquisition and antibiotic selective pressure. Biofilm-forming ability varies with the prevalent CRAB clone. The wide spread of clone B is of concern.