Related Experiment Video
Updated: May 4, 2026
A Soluble Tetrazolium-Based Reduction Assay to Evaluate the Effect of Antibodies on Candida tropicalis Biofilms
Published on: September 16, 2022
Efficacy of dental unit disinfectants against Candida spp. and Hartmannella vermiformis
Vanessa Barbot1, Damien Costa, Marie Deborde
1Laboratoire d'Ecologie et de Biologie des Interactions, Université de Poitiers, UMR CNRS 7267, Poitiers Cedex, France.
Abstract:
Human oral commensal Candida yeasts, as well as environmental free-living amoebae (FLA) such as Hartmannella, are known to be direct or indirect human pathogens. These microorganisms may be isolated from dental unit waterlines (DUWL), because of contamination coming from the tap water and/or a patient's mouth. This study compared the efficacy of commonly used DUWL disinfectants (chlorine, H2 O2 , and Oxygenal 6©) against three species of Candida (C. albicans, C. glabrata, and C. parapsilosis) and one FLA species (H. vermiformis), growing either as single or as mixed biofilms in tap water. Results showed variable efficacies: H2 O2 had no significant activity, while chlorine was effective but only at the highest doses tested, probably not compatible with DUWL uses. Oxygenal 6© was the most efficacious in preventing the growth of yeasts in tap water. However, in the presence of FLA, Oxygenal 6© displayed a reduced antimicrobial activity against sessile C. albicans. In conclusion, none of the tested disinfectants could eradicate yeasts or FLA. Moreover, the antiyeast activity of Oxygenal 6© was reduced in the presence of FLA. Both sessile or planktonic and mixed or single-species conditions should be considered when evaluating the activity of disinfectants for DUWL maintenance. This study also highlighted that FLA should be included in the testing protocols.
Insights
Dental disinfectants show limited efficacy against Candida yeasts and free-living amoebae (FLA) in biofilms. Oxygenal 6© was most effective against yeasts alone, but its activity decreased when FLA were present, highlighting the need for comprehensive testing protocols.
Area of Science:
- Microbiology
- Environmental Health
- Dental Public Health
Background:
- Human oral commensal yeasts (Candida spp.) and environmental free-living amoebae (FLA) are potential pathogens.
- These microorganisms can contaminate dental unit waterlines (DUWL) from tap water or patients.
- DUWL contamination poses a risk for healthcare-associated infections.
Purpose of the Study:
- To compare the efficacy of common DUWL disinfectants against Candida yeasts and FLA.
- To evaluate disinfectant effectiveness on single and mixed biofilms in tap water.
- To determine if FLA presence affects disinfectant efficacy against Candida.
Main Methods:
- Tested disinfectants: chlorine, hydrogen peroxide (H2 O2), and Oxygenal 6©.
- Evaluated against Candida albicans, Candida glabrata, Candida parapsilosis, and Hartmannella vermiformis.
- Assessed efficacy on single-species and mixed-species biofilms in tap water.
Main Results:
- Hydrogen peroxide showed no significant antimicrobial activity.
- Chlorine was effective only at high concentrations, potentially unsuitable for DUWL.
- Oxygenal 6© was most effective against yeasts in tap water but showed reduced efficacy against Candida in the presence of FLA.
Conclusions:
- None of the tested disinfectants eradicated yeasts or FLA from DUWL biofilms.
- FLA presence significantly reduced the anti-yeast activity of Oxygenal 6©.
- Disinfectant testing for DUWL maintenance should consider both sessile/planktonic and single/mixed-species conditions, including FLA.
More Related Videos
06:39Author Spotlight: Exploring Photodynamic Therapy with Curcumin in a Murine Model for Oral Candidiasis
Published on: October 27, 2023
08:20Systematic Approach to Identify Novel Antimicrobial and Antibiofilm Molecules from Plants' Extracts and Fractions to Prevent Dental Caries
Published on: March 31, 2021
Related Concept Videos
01:28Antimicrobial Effectiveness
01:23Hand hygiene
Hand washing...