title: No evidence of triclosan-resistant bacteria following long-term use of triclosan-containing toothpaste.
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  The use of TCS-containing toothpaste did not appear to lead to an increase in MIC of TCS of oral bacterial isolates.
authors.affiliation: Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand; School of Medicine, Prince Charles Hospital, University of Queensland, Brisbane, Qld, Australia.
authors.forename: M P
authors.initials: MP
authors.lastname: Cullinan
authors.forename: P S
authors.initials: PS
authors.lastname: Bird
authors.forename: N C K
authors.initials: NC
authors.lastname: Heng
authors.forename: M J
authors.initials: MJ
authors.lastname: West
authors.forename: G J
authors.initials: GJ
authors.lastname: Seymour
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects / Q000302:isolation & purification; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use*; D001419:Bacteria / Q000145:classification / Q000187:drug effects*; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects*; D002167:Campylobacter / Q000187:drug effects / Q000302:isolation & purification; D055113:Chronic Periodontitis / Q000517:prevention & control; D003773:Dental Plaque / Q000382:microbiology / Q000517:prevention & control; D024881:Drug Resistance, Bacterial; D005500:Follow-Up Studies; D016967:Fusobacterium nucleatum / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests; D010919:Placebos; D016966:Porphyromonas gingivalis / Q000187:drug effects / Q000302:isolation & purification; D018720:Prevotella / Q000187:drug effects / Q000302:isolation & purification; D034366:Streptococcus anginosus / Q000187:drug effects / Q000302:isolation & purification; D013295:Streptococcus mutans / Q000187:drug effects / Q000302:isolation & purification; D014100:Toothpastes / Q000627:therapeutic use*; D014260:Triclosan / Q000627:therapeutic use*; D014678:Veillonella / Q000187:drug effects / Q000302:isolation & purification
chemical_list: D000891:Anti-Infective Agents, Local; D010919:Placebos; D014100:Toothpastes; D014260:Triclosan
keywords: antimicrobial resistance; oral bacteria; toothpaste; triclosan