title: Quantification of vital adherent Streptococcus sanguinis cells on protein-coated titanium after disinfectant treatment.
abstract: The quantification of vital adherent bacteria is challenging, especially when efficacy of antimicrobial agents is to be evaluated. In this study three different methods were compared in order to quantify vital adherent Streptococcus sanguinis cells after exposure to disinfectants. An anaerobic flow chamber model accomplished initial adhesion of S. sanguinis on protein-coated titanium. Effects of chlorhexidine, Betadine®, Octenidol®, and ProntOral® were assessed by quantifying vital cells using Live/Dead BacLight™, conventional culturing and isothermal microcalorimetry (IMC). Results were analysed by Kruskal-Wallis one-way analysis of variance. Live/dead staining revealed highest vital cell counts (P < 0.05) and demonstrated dose-dependent effect for all disinfectants. Microcalorimetry showed time-delayed heat flow peaks that were proportioned to the remaining number of viable cells. Over 48 h there was no difference in total heat between treated and untreated samples (P > 0.05), indicating equivalent numbers of bacteria were created and disinfectants delayed growth but did not eliminate it. In conclusion, contrary to culturing, live/dead staining enables detection of cells that may be viable but non-cultivable. Microcalorimetry allows unique evaluation of relative disinfectant effects by quantifying differences in time delay of regrowth of remaining vital cells.
authors.affiliation: Institute of Preventive Dentistry and Oral Microbiology, School of Dental Medicine, University of Basel, Basel, Switzerland. m.astasov-frauenhoffer@unibas.ch
authors.forename: Monika
authors.initials: M
authors.lastname: Astasov-Frauenhoffer
authors.forename: Olivier
authors.initials: O
authors.lastname: Braissant
authors.forename: Irmgard
authors.initials: I
authors.lastname: Hauser-Gerspach
authors.forename: A U
authors.initials: AU
authors.lastname: Daniels
authors.forename: Dieter
authors.initials: D
authors.lastname: Wirz
authors.forename: Roland
authors.initials: R
authors.lastname: Weiger
authors.forename: Tuomas
authors.initials: T
authors.lastname: Waltimo
mesh_terms: D000704:Analysis of Variance; D001422:Bacterial Adhesion; D002151:Calorimetry; D004202:Disinfectants / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D011506:Proteins; D013298:Streptococcus sanguis / Q000187:drug effects / Q000502:physiology*; D014025:Titanium
chemical_list: D004202:Disinfectants; D011506:Proteins; D014025:Titanium