The Erythromycin Penetration Through Staphylococcus epidermidis Biofilm

Abstract:

To explore the erythromycin penetration through Staphylococcus epidermidis biofilm. The penetration ratio of erythromycin through Staphylococcus epidermidis biofilm of 1457, 1457-msrA and S68 isolates were detected by biofilm penetration model at different time points. The RNA/DNA ratio and the cell density within the biofilms were observed by confocal laser microscope and transmission electromicroscope, respectively. The penetration ratios of erythromycin through the biofilms of 1457, 1457-msrA and S68 after 36 h were 0.93, 0.55 and 0.4, respectively. The erythromycin penetration ratio through 1457 biofilm (with 0.58 after 8 h) was faster than two others (with 0.499 and 0.31 after 24 h). The slower growth rate of the cells in biofilm was shown, with reduction of RNA/DNA proportion observed by confocal laser microscope through acridine orange stain. Compared with the control group observed by transmission electrmicroscope, the cell density of biofilm air face was lower than that of agar face, with more cell debris. Erythromycin could penetrate into the Staphylococcus epidermidis biofilm, but couldn’t kill the cells thoroughly. The lower growth rate of the cells within biofilm could help to decrease the erythromycin susceptibility.

Key words:Staphylococcus epidermidis, Biofilm, Penetration ratio