TÌNH HÌNH ĐỀ KHÁNG THUỐC KHÁNG NẤM CỦA MALASSEZIA SPP. TRÊN BỆNH NHÂN NẤM DA TẠI BỆNH VIỆN DA LIỄU THÀNH PHỐ HỒ CHÍ MINH

Abstract

Objective: To determine the antifungal resistance rate of Malassezia species isolated from patients with pityriasis versicolor attending Ho Chi Minh City Dermatology Hospital. Methods: A cross-sectional descriptive study was conducted on 175 patients clinically diagnosed with pityriasis versicolor from March to October 2025. Skin scale samples were cultured on Sabouraud Dextrose Agar (SDA) and mDixon media for isolation of Malassezia spp. The isolates were identified based on their morphological and biochemical characteristics. Antifungal susceptibility testing was performed by broth microdilution according to the Clinical and Laboratory Standards Institute (CLSI) M27-A3 guidelines for azole antifungal agents. As no official breakpoints are currently established for the genus Malassezia, the cutoff values were defined based on international consensus and CLSI standards for Candida spp., with MIC ≥ 1 µg/mL for itraconazole and ≥ 8 µg/mL for fluconazole. Results: Among 175 samples, 99 (56.6%) yielded positive cultures, identifying eight Malassezia species. The predominant isolates were M. furfur (36.4%), M. globosa (28.3%), and M. dermatis (18.2%). Itraconazole exhibited the strongest activity (MIC₅₀ = 0.063–0.125 µg/mL), with only one M. globosa isolate (3.7%) exceeding the resistance threshold. In contrast, fluconazole showed weaker activity, with high resistance rates observed in M. furfur (58.3%) and M. globosa (48.1%), while M. dermatis remained fully susceptible. Significant differences in MIC values among species were observed for both agents (p < 0.001). Conclusion: Fluconazole resistance was notably prevalent in M. furfur and M. globosa, whereas itraconazole maintained potent activity and remains the preferred systemic treatment, particularly in recurrent or multi-species infections. These findings provide updated local data on Malassezia susceptibility and support rational antifungal selection in clinical practice.