Vancomycin Promotes the Bacterial Autolysis, Release of Extracellular DNA, and Biofilm Formation in Vancomycin-non-Susceptible Staphylococcus aureus.

• Main Authors: Chi Yu Hsu, 徐啟育
• Other Authors: J. C. Shu
• Format: Others
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/16108511334120609795

碩士 === 長庚大學 === 醫學生物技術暨檢驗學系 === 100 === Staphylococcus aureus, an important human pathogen, is particularly adept at producing biofilms on implanted medical devices. Although antibiotic treatment of non-susceptible bacteria will not kill these strains, the consequences should be studied. The present study focuses on investigating the effect of vancomycin on biofilm formation by vancomycin-non-susceptible S. aureus. Biofilm adherence assays and scanning electron microscopy demonstrated that biofilm formation was significantly enhanced following vancomycin treatment. Bacterial autolysis of some subpopulations was observed and was confirmed by the live/dead staining and confocal laser scanning microscopy (CLSM). A significant increase in polysaccharide intercellular adhesin (PIA) production was observed by measuring icaA transcript levels and in a semi-quantitative PIA assay in one resistant strain. We show that the release of extracellular DNA (eDNA) via cidA-mediated autolysis is a major contributor to vancomycin-enhanced biofilm formation. The addition of xenogeneic DNA could also significantly enhance biofilm formation by a PIA-overproducing S. aureus strain. The magnitude of the development of the biofilm depends on the balance between the amounts of eDNA and PIA. In conclusion, sublethal doses of cell wall-active antibiotics like vancomycin induce biofilm formation through an autolysis-dependent mechanism in vancomycin-non-susceptible S. aureus.