Yeasts as Important Agents of Onychomycosis: In Vitro Activity of Propolis Against Yeasts Isolated from Patients with Nail Infection

Objective: The purposes of this study were to determine the frequency of the yeast species obtained from patients with clinical features of onychomycosis and the in vitro antifungal susceptibility of the yeast species to propolis.

Methods: A prospective study was carried out at the Mycology Research Center in Iran from 2010 to 2011. Clinical diagnosis was performed by direct microscopic examination and culture. Different yeast species were identified by morphological and biochemical tests. An antifungal susceptibility test to fluconazole (FLU) and propolis by the broth microdilution method was performed on each isolate.

Results: One hundred and twenty-eight fungal isolates were obtained. The most prevalent fungi were yeasts (81, 63.2%), dermatophytes (36, 28.1%), and nondermatophyte fungi (11, 8.6%). Fingernails were more affected than toenails (65.4% vs. 19.8%, respectively). The most frequently found species was Candida albicans (38.5%), followed by Candida spp. (23.1%), C. tropicalis (10.8%), C. kefyr (6.2%), C. krusei (3.1%), Malassezia globosa (4.6%), M. slooffiae (4.6%), and M. pachydermatis (1.5%). Of all yeast isolates (65), seven showed resistance to FLU. The average MIC of propolis for FLU-susceptible isolates was 5.8 μg/mL, whereas this value was 12.25 μg/mL for FLU-resistant isolates.

Conclusion: Our results proved that the propolis inhibits the growth of pathogenic yeasts and confirmed the efficiency of propolis as an anti-Candida and anti-Malassezia agent.