Commercial mouthwashes are ineffective against oral MRSA biofilms.

Objective: The aim of this study was to evaluate and compare the activity of oral mouthwashes against biofilm forms of MRSA isolated from the oral cavity and the bloodstream.

Study Design: The time-kill kinetics efficacy of 7 over-the-counter mouthwashes were tested against 28 clinical MRSA biofilm isolates for 0.5, 1 and 2 min.

Results: Treatments of MRSA biofilms formed by oral and bloodstream isolates were not significantly different, with mouthwashes displaying a rapid and modest anti-biofilm effect. None of the biofilm isolates were completely eradicated by the compounds tested, with a maximal killing of only approximately 70% shown by Corsodyl and Peroxyl. Maximum activity of all compounds tested was observed after 0.5 min. Fluorigard showed the poorest overall activity (57% reduction).

Conclusions: MRSA colonize the oral cavity, and are more prevalent in institutionalized persons and the elderly. Over-the-counter mouthwashes are ineffective at killing MRSA biofilms, which has infection control implications.