Susceptibilities of Enterococcus faecalis biofilms to some antimicrobial medications

Enterococcus faecalis has been suggested to be an important etiological age nt in endodontic failures. The purpose of this study was to evaluate the ef fectiveness of chlorhexidine- or antibiotics-based medications in eliminati ng E. faecalis biofilms. One-day and three-day biofilms of E. faecalis were induced on cellulose nitrate membrane filters. Each biofilm-containing mem brane was thoroughly covered with 1 ml of the test medications and incubate d for 1 day at 37 degreesC. Treated biofilms were then aseptically transfer red to vials containing a neutralizing agent in saline solution and vortexe d. Suspensions were 10-fold diluted, seeded onto Mitis salivarius agar plat es, and the colony-forming units counted after 48 h of incubation. There we re significant differences between the formulations tested. The association of clindamycin with metronidazole significantly reduced the number of cell s in 1-day biofilms. However of all medications tested, only 2% chlorhexidi ne-containing medications were able to thoroughly eliminate most of both 1- day and 3-day E. faecalis biofilms.