Susceptibility of Candida albicans biofilms grown in a constant depth film fermentor to chlorhexidine, fluconazole and miconazole: a longitudinal study.
OBJECTIVE
The aim of this study was to assess the resistance of Candida albicans biofilms to both antifungal and antimicrobial agents in vitro.


METHODS
Biofilms of C. albicans were grown on denture acrylic discs in a constant depth film fermentor and maintained with artificial saliva. The MIC of fluconazole, miconazole and chlorhexidine for C. albicans was first determined. Using these data, 72 h biofilms were exposed to these agents at different MIC levels. In order to assess growth, biofilms were removed from the fermentor, incubated in the test agent for various periods, the biofilms disrupted and the viable yeast cells present determined. The MIC for these cells was then also determined. In a separate experiment, biofilms of various ages (2-72 h) were exposed to sub-biofilm MIC concentrations for two different periods.


RESULTS
C. albicans biofilms were found to be highly resistant to fluconazole and miconazole compared with the same cells grown in suspension (>/=1024 x MIC). In contrast, chlorhexidine inhibited the growth of C. albicans biofilms at a concentration up to 8 x MIC. When the susceptibility of biofilms over time was investigated, higher reductions were observed for chlorhexidine and miconazole than fluconazole for biofilms of 2 and 6 h.


CONCLUSIONS
We have shown in this study that the susceptibility of C. albicans to antifungal and antimicrobial agents changes throughout biofilm development.
Lamfon
Hanadi
H
Division of Infection and Immunity, Eastman Dental Institute, University College London, 256 Gray's Inn Road, London WC1X 8LD, UK.
Porter
Stephen R
SR
McCullough
Michael
M
Pratten
Jonathan
J
D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development; D002710:Chlorhexidine / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D005285:Fermentation; D015725:Fluconazole / Q000494:pharmacology*; D008137:Longitudinal Studies; D008825:Miconazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests
D000935:Antifungal Agents; D004202:Disinfectants; D008825:Miconazole; D015725:Fluconazole; D002710:Chlorhexidine