title: Subinhibitory concentrations of triclosan promote Streptococcus mutans biofilm formation and adherence to oral epithelial cells.
abstract: Triclosan is a general membrane-active agent with a broad-spectrum antimicrobial activity that is commonly used in oral care products. In this study, we investigated the effect of sub-minimum inhibitory concentrations (MICs) of triclosan on the capacity of the cariogenic bacterium Streptococcus mutans to form biofilm and adhere to oral epithelial cells. As quantified by crystal violet staining, biofilm formation by two reference strains of S. mutans was dose-dependently promoted, in the range of 2.2- to 6.2-fold, by 1/2 and 1/4 MIC of triclosan. Observations by scanning electron microscopy revealed the presence of a dense biofilm attached to the polystyrene surface. Growth of S. mutans in the presence of triclosan at sub-MICs also increased its capacity to adhere to a monolayer of gingival epithelial cells. The expression of several genes involved in adherence and biofilm formation in S. mutans was investigated by quantitative RT-PCR. It was found that sub-MICs of triclosan significantly increased the expression of comD, gtfC, and luxS, and to a lesser extent of gtfB and atlA genes. These findings stress the importance of maintaining effective bactericidal concentrations of therapeutic triclosan since sub-MICs may promote colonization of the oral cavity by S. mutans.
authors.affiliation: Department of Oral Diagnosis and Surgery, Araraquara Dental School, State University of São Paulo, São Paulo, Brazil.
authors.forename: Telma Blanca Lombardo
authors.initials: TB
authors.lastname: Bedran
authors.affiliation: Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Louis
authors.initials: L
authors.lastname: Grignon
authors.affiliation: Department of Physiology and Pathology, Araraquara Dental School, State University of São Paulo, São Paulo, Brazil.
authors.forename: Denise Palomari
authors.initials: DP
authors.lastname: Spolidorio
authors.affiliation: Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grenier
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000382:microbiology; D015870:Gene Expression / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D013295:Streptococcus mutans / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D014260:Triclosan / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D014260:Triclosan