Formation of Biofilm by Slime Producing Staphylococcus epidermidis and Bactericidal Activity of Cefazolin

Abstract

Slime production was studied in a total of 598 strains of Staphylococcus aureus and 11 species of coagulase negative staphylococci and the relationship of the slime production and biofilm formation was investigated
The high slime production was obtained in 42 of 263 strains (16%) of S. epidermidis only. The adherence ofS. epidermidisto biomedical silicone discs (S discs) and biofilm formation were investigatedin vitroin high slime producing and non-producing strains. The adherence rates ofS. epidermidisto the S discs ranged from 2.3 to 14.8%. There was no relationship between slime production byS. epidermidisand the adherence rates. Biofilm was formed only in slime producing strains with cell growth on the S discs when they were incubated. The process of the biofilm formation was obtained by scanning electron microscopy; there were many projections, probably slime secreted from the cells, on the cell surface, and picture showing agglutination of cell by crosslinking. The bactericidal activity of cefazolin, cefmetazole and flumoxef againstS. epidermidisafter formation of the biofilm decreased more markedly than that before formation. Cefazolin reduced the number ofS. epidermidisand eliminated the formed biofilm in anin vitrosimulation model of serum concentration in human after drip infusion of 2 g of cefazolin.