title: The antibacterial activity of chlorhexidine digluconate against Streptococcus mutans biofilms follows sigmoidal patterns.
abstract: The aim of this study was to determine the pattern of the antibacterial activity of chlorhexidine digluconate (CHX) against mature Streptococcus mutans biofilms. Streptococcus mutans biofilms were formed on saliva-coated hydroxyapatite discs and then treated with 0-20% CHX, once, three times, or five times (1 min per treatment) during the period of mature biofilm formation (beyond 46 h). After the treatments, the colony-forming unit (CFU) counts of the treated biofilms were determined. The pH values of the spent culture medium were also determined to investigate the change in pH resulting from the antibacterial activity of CHX. The relationships between the concentration of CHX and the CFU counts and the concentration of CHX and culture medium pH, relative to the number of treatments performed, were evaluated using a sigmoidal curve-fitting procedure. The changes in CFU counts and culture medium pH followed sigmoidal curves and were dependent on the concentration of CHX (R2= 0.99). The sigmoidal curves were left-shifted with increasing number of treatments. Furthermore, the culture-medium pH of the treated biofilms increased as their CFU counts decreased. The lowest CHX concentration to increase culture-medium pH above the critical pH also decreased as the number of treatments increased. These results may provide fundamental information for selecting the appropriate CHX concentrations to treat S. mutans biofilms.
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Institute of Oral Bioscience and BK 21 Plus Program, Chonbuk National University, Jeonju, Korea.|Department of Pediatric Dentistry, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, Korea.
authors.forename: Dae-Woo
authors.initials: DW
authors.lastname: Lee
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Institute of Oral Bioscience and BK 21 Plus Program, Chonbuk National University, Jeonju, Korea.
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Jung
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, Korea.
authors.forename: Yeon-Mi
authors.initials: YM
authors.lastname: Yang
authors.affiliation: Department of Pediatric Dentistry, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, Korea.
authors.forename: Jae-Gon
authors.initials: JG
authors.lastname: Kim
authors.affiliation: Department of Oral Biochemistry, School of Dentistry, Institute of Oral Bioscience, Chonbuk National University, Jeonju, Korea.
authors.forename: Ho-Keun
authors.initials: HK
authors.lastname: Yi
authors.affiliation: Department of Preventive Dentistry, School of Dentistry, Institute of Oral Bioscience and BK 21 Plus Program, Chonbuk National University, Jeonju, Korea. dentjjk@jbnu.ac.kr.
authors.forename: Jae-Gyu
authors.initials: JG
authors.lastname: Jeon
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D013295:Streptococcus mutans / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; C010882:chlorhexidine gluconate; D002710:Chlorhexidine
keywords: Streptococcus mutans biofilms; antibacterial activity; chlorhexidine digluconate