Effects of vancomycin (VAN) on virulence factors of Staphylococcus aureus.

GORDIOLA, M; BARBAGELATA, MS; ALVAREZ, LP; CERQUETTI, MC; SORDELLI, DO; BUZZOLA FR

Cordoba

Simposio; 44th Annual Meeting, Argentine Society for Biochemistry and Molecular Biology Research,; 2008

The glycopeptide VAN is a bacteriocin produced by Streptomyces orientalis that is used for serious infections caused by methicillin-resistant S. aureus. VAN blocks the action of transpeptidase during the synthesis of peptidoglycan. Subinhibitory concentrations (SubMIC) of some antibiotics can affect the expression of bacterial virulence factors. We hypothesized that subMIC of VAN may have effects on virulence factors of S. aureus. The VAN MIC of the Newman strain was 7 µg/ml. After subMIC exposure, a reduction of polysaccharide capsular production was determined by immunoprecipitation assays. Proteins profiles of Newman strain and its isogenic regulatory mutants cultured with or without VAN were analyzed by SDS-PAGE. We observed that several cell wall proteins regulated by sae were inhibited by VAN. In contrast, VAN induced the increase of several cell wall protein regulated by mgrA. Moreover, a particular surface protein of Newman strain showed to be increased after growth with VAN. The pattern of haemolysins (á, â, ä) expression of Newman and its regulatory mutants was not modified by VAN. Our results suggests that subMIC of VAN reduce the capsule production and alter the expression of surface and cell wall proteins patterns of Newman strain.