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

Abstract

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 μg/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 μg/mL) and incubated at 37°C under microaerophilic and anaerobic conditions for 2-10 d. Selected bacterial isolates were identified by partial 16S rDNA sequencing and TCS minimum inhibitory concentration (MIC) determined for each isolate. Results: At 3000 μg/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 μg/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. © 2013 John Wiley & Sons A/S.