effect of cryptotanshinone on staphylococcus epidermidis biofilm formation under in vitro conditions

Background: staphylococcus epidermidis causes prosthetic valve endocarditis, urinary tract infection, and implant-related infec- tions. these are difficult to treat often due to drug resistance, particularly because s. epidermidis biofilms are inherently resistant to most antibiotics. salvia miltiorrhiza is a kind of sichuan-specific medicinal herb, and has effective ingredients, such as cryptotanshi- none. cryptotanshinone was demonstrated to have anti-microbial properties and no resistance. objectives: the current study investigated the effects of cryptotanshinone on s. epidermidis biofilm formation, and found new agents controlling s. epidermidis biofilm formation and resistance caused by biofilm. methods: the effects were further analyzed by crystal violet assay (cv), 2, 3-bis [2-methoxy-4-nitro-5-sulfophenyl]-2h-tetrazolium-5- carboxanilide inner salt assay (xtt), and scanning electron microscopy (sem). the qrt-pcr assay was used to determine the expres- sions of biofilm key genes, including icaa, atle, aap and luxs. results: the amount treated by cryptotanshinone was reduced compared with the non-treating group, so did the metabolic activity inside the biofilm. even the micro-structure was destroyed with cryptotanshinone. the expressions of biofilm key genes, including icaa, atle, aap, and luxs, were down-regulated by cryptotanshinone. conclusions: there is new insight that cryptotanshinone could inhibit immature biofilms and the down-regulations of icaa, atle, aap, and luxs might explain this inhibitory effect.