Susceptibility of Candida biofilms to histatin 5 and fluconazole.
Candida-associated denture stomatitis has a high rate of recurrence. Candida biofilms formed on denture acrylic are more resistant to antifungals than planktonic yeasts. Histatins, a family of basic peptides secreted by the major salivary glands in humans, especially histatin 5, possess significant antifungal properties. We examined antifungal activities of histatin 5 against planktonic or biofilm Candida albicans and Candida glabrata. Candida biofilms were developed on poly(methyl methacrylate) discs and treated with histatin 5 (0.01-100 microM) or fluconazole (1-200 microM). The metabolic activity of the biofilms was measured by the XTT reduction assay. The fungicidal activity of histatin 5 against planktonic Candida was tested by microdilution plate assay. Biofilm and planktonic C. albicans GDH18, UTR-14 and 6122/06 were highly susceptible to histatin 5, with 50% RMA (concentration of the agent causing 50% reduction in the metabolic activity; biofilm) of 4.6 +/- 2.2, 6.9 +/- 3.7 and 1.7 +/- 1.5 microM, and IC(50) (planktonic cells) of 3.0 +/- 0.5, 2.6 +/- 0.1 and 4.8 +/- 0.5, respectively. Biofilms of C. glabrata GDH1407 and 6115/06 were less susceptible to histatin 5, with 50% RMA of 31.2 +/- 4.8 and 62.5 +/- 0.7 microM, respectively. Planktonic C. glabrata was insensitive to histatin 5 (IC(50) > 100 microM). Biofilm-associated Candida was highly resistant to fluconazole in the range 1-200 microM; e.g. at 100 microM only approximately 20% inhibition was observed for C. albicans, and approximately 30% inhibition for C. glabrata. These results indicate that histatin 5 exhibits antifungal activity against biofilms of C. albicans and C. glabrata developed on denture acrylic. C. glabrata is significantly less sensitive to histatin 5 than C. albicans.
Department of Microbiology, Arthur A. Dugoni School of Dentistry, University of the Pacific, 2155 Webster Street, San Francisco, CA 94115, USA. kkonopka@pacific.edu
Krystyna
K
Konopka
Barbara
B
Dorocka-Bobkowska
Senait
S
Gebremedhin
Nejat
N
Düzgüneş
D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects* / Q000502:physiology; D041221:Candida glabrata / Q000187:drug effects* / Q000502:physiology; D015169:Colony Count, Microbial; D015725:Fluconazole / Q000494:pharmacology*; D054808:Histatins / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects
D000935:Antifungal Agents; D054808:Histatins; D015725:Fluconazole