No evidence of triclosan-resistant bacteria following long-term use of triclosan-containing toothpaste

Background and Objective There is a paucity of data in relation to the possible emergence of triclosan (TCS)-resistant bacteria following long-term exposure to TCS toothpaste. Therefore, this study investigated whether long-term continuous exposure to TCS in toothpaste selects for TCS-resistant bacteria within the oral biofilm. Material and Methods Dental plaque samples were collected from 40 individuals during year 5 of a randomised controlled trial. Participants had been randomly assigned to use TCS (3000 mu g/mL TCS) (n=18) or placebo toothpaste (n=22). Diluted plaque samples were plated on to Wilkins-Chalgren agar plates containing 5% (v/v) laked sheep red blood cells and TCS (concentrations ranging from 25 to 150 mu g/mL) and incubated at 37 degrees C under microaerophilic and anaerobic conditions for 2-10d. Selected bacterial isolates were identified by partial 16S rDNA sequencing and TCS minimum inhibitory concentration (MIC) determined for each isolate. Results At 3000 mu g/mL TCS no growth was observed under microaerophilic or anaerobic conditions in either group. The MICs of TCS for all isolates ranged from 125 to 1000 mu g/mL in both groups. Species common to both groups had similar MICs. Veillonella parvula and Campylobacter gracilis were the most frequent isolates from both groups, with similar MICs in both groups. Conclusion The use of TCS-containing toothpaste did not appear to lead to an increase in MIC of TCS of oral bacterial isolates.