Inhibitory effects of polysorbate 80 on MRSA biofilm formed on different substrates including dermal tissue.

Methicillin-resistant Staphylococcus aureus (MRSA) forms biofilms on necrotic tissues and medical devices, and causes persistent infections. Surfactants act on biofilms, but their mode of action is still unknown. If used in the clinic, cytotoxicity in tissues should be minimized. In this study, we investigated the inhibitory effect of four different surfactants on MRSA biofilm formation, and found that a nonionic surfactant, polysorbate 80 (PS80), was the most suitable. The biofilm inhibitory effects resulted from the inhibition of bacterial adhesion to substrates rather than biofilm disruption, and the effective dose was less cytotoxic for 3T3 fibroblasts. However, the effects were substrate-dependent: positive for plastic, silicon, and dermal tissues, but negative for stainless-steel. These results indicate that PS80 is effective for prevention of biofilms formed by MRSA on tissues and foreign bodies. Therefore, PS80 could be used in medical practice as a washing solution for wounds and/or pretreatment of indwelling catheters.