Abstract: Apoptosis occupied the dominant status of the programmed cell death (PCD), which is often considered to be unique to eukaryotes. Bacterial Cid/Lrg systems similar to eukaryotic apoptosis have also been concerned. Staphylococcus epidermidis is one of the most important pathogens causing nosocomial infections; and the pathogenesis of S. epidermidis is closely related to the formation of biofilms on the surface of artificial devices (joints, contact lenses, heart valves, indwelling catheters, etc.) implant in the human body. To evaluate the effects of sodium houttuyfonate and its combination with erythromycin on the dissolution and biofilm formation of S. epidermidis, the MIC of sodium houttuyfonate, erythromycin and vancomycin against S. epidermidis was determined by serial dilution method. Fluorescence quantitative PCR was used to determine the transcription level of lrgB（Gene B regulated by lytSR） in different time periods after the action of sodium houttuyfonate and its combination with erythromycin, erythromycin and vancomycin on S. epidermidis. The effect of sodium houttuyfonate and erythromycin on the morphology of S. epidermidis biofilm was observed under a microscope. It was found that the combination of sodium houttuyfonate and erythromycin significantly increased the expression of lrgB at the beginning of the treatment (P<0.05). The sub-inhibitory concentration of sodium houttuyfonate combined with erythromycin also significantly down-regulated the expression of lrgB at 6 h, 12 h, 24 h and 48 h (P<0.05). Morphological observation also confirmed the destructive effect of the sub-inhibitory concentration of sodium houttuyfonate combined with erythromycin on the biofilm of S. epidermidis. The experimental results confirmed that the combination of sodium houttuyfonate and erythromycin could regulate the expression of lrgB at a specific concentration, thus inhibiting and destroying the formation of S. epidermidis biofilm and promoting the dissolution and death of bacteria.

Key words: Staphylococcus epidermidis, sodium houttuyfonate, erythromycin, PCD, lrgB, biofilm