Antifungal susceptibility testing of Malassezia spp isolated from patients with Pityriasis versicolor and healthy individuals

Abstract

Background: The genus Malassezia is a normal flora of our body. It needs lipid supplements for its growth and is seen in the area rich in sebaceous glands. It is a causative agent of Pityriasis versicolor (PV), Malassezia folliculitis, seborrheic dermatitis and also associated with some systemic infection like fungemia, catheter acquired sepsis in patients receiving lipid parenteral nutrition. Increased incidence of Malassezia infection emphasizes the need of susceptibility to choose a specific and accurate treatment. The aim of this study was to evaluate the in-vitro activity of amphotericin B, fluconazole, ketoconazole and voriconazole against the Malassezia spp isolated from PV and healthy individuals. Methodology: Modification of the CLSI M27-A3 document method using Christensen's urea broth with the addition of 0.5% Tween 40 and 0.1% Tween 80 was performed to evaluate the optimal antifungal susceptibility patterns of the isolates. Results: The Malassezia spp from healthy and PV patients shows variability in susceptibility pattern. Among the different species the lowest Microbial Inhibition Concentration (MICs) were found in amphotericin B, ketoconazole and Fluconazole with MIC50 values of 0.62, 0.03 and 0.125 in healthy individuals respectively. Isolates from PV patients showed slight highest value of MIC50 0.5, 0.25 and 0.5 respectively. Conclusion: The susceptibility pattern showed intra species variation and difference between healthy and PV patients as well. This emphasizes the need to identify the species and to evaluate the antifungal susceptibility of Malassezia. Further investigation is needed to correlate the in-vitro activity of antifungal agents with clinical outcomes.

Keywords

• antifungal susceptibility
• pityriasis versicolor
• drug resistance
• malassezia