Susceptibility of Candida biofilms to histatin-5 and fluconazole

ORCiD

Nejat Düzgüneş: 0000-0001-6159-1391

Department

Biomedical Sciences

Document Type

Conference Presentation

Conference Title

39th Annual Meeting of the American Association for Dental Research (AADR)

Location

Washington, DC

Conference Dates

March 3-6, 2010

Date of Presentation

3-6-2010

Journal Title

Journal of Dental Research

Journal ISSN

0022-0345

Journal Volume Number

89 (Special issue A)

First Page

1461

Abstract

Objectives: The high recurrence rate of Candida-associated denture stomatitis may be explained by the greater antibiotic resistance of Candida biofilms formed on denture acrylic, compared to planktonic yeasts. Among the salivary histatins, histatin-5 (Hst-5) shows significant antifungal activity. We investigated the effect of Hst-5 and fluconazole on C. albicans and C. glabrata biofilms formed on denture acrylic discs. Methods: Three C. albicans isolates, GDH18, UTR-14 (ATCC), and 6122/06 (clinical), and two C. glabrata isolates, GDH1407 (ATCC) and 6115/06 (clinical) were used. Biofilms were developed on poly(methyl methacrylate) discs incubated for 90 min at 37°C (adherence). After removal of non-adherent cells, discs were submerged in YNB/100 mM glucose and incubated for 48 h at 37°C (biofilm formation). Biofilms were rinsed with 10 mM sodium phosphate buffer and incubated with Hst-5 (0.01-100 µM) for 1 h at 37°C. Fluconazole (1-200 µM) was added in YNB medium and incubated for 24 h at 37°C. The metabolic activity of the biofilms was measured by the XTT assay. Results: Biofilms of C. albicans GDH18, UTR-14 and 6122/06 were highly susceptible to Hst-5, with IC50 of 4.6±2.2, 6.9±3.7 and 1.7±1.5 µM, respectively. Biofilms of C. glabrata GDH1407 and 6115/06 were less susceptible to Hst-5, with IC50 of 31.2±4.8 and 62.5±0.7 µM, respectively. Biofilm-associated Candida was highly resistant to fluconazole in the range 1-200 µM; e.g. at 100 µM only ~20% inhibition was observed for C. albicans, and ~30% inhibition for C. glabrata. Conclusion: Hst-5 exhibited antifungal activity against C. albicans and C. glabrata biofilms on denture acrylic. C. glabrata biofilms were significantly less sensitive to Hst-5 than C. albicans biofilms. Fluconazole was ineffective against C. albicans biofilms. Supported by Research Pilot Project Award 03-Activity 054 from the University of the Pacific, Arthur A. Dugoni School of Dentistry (K. Konopka).

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