Isolation of Malassezia Species from Clinically Diagnosed Cases of Pityriasis Versicolor and Seborrheic Dermatitis and Determination of Antifungal Susceptibility of the Isolates

Jersey Gayathiri, M (2015) Isolation of Malassezia Species from Clinically Diagnosed Cases of Pityriasis Versicolor and Seborrheic Dermatitis and Determination of Antifungal Susceptibility of the Isolates. Masters thesis, Madras Medical College, Chennai.


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INTRODUCTION: Ever since its inception, the genus Malassezia has been a topic of intense basic research in various aspects including taxonomy, physiology, epidemiology, metabolomics and immunology. The etiopathologic links between these yeasts and many superficial and systemic infections have been unveiled by clinical research. Pityriaisvericolor (PV) and seborrheic dermatitis (SD) are superficial skin infections that have an established causal association with Malassezia species. OBJECTIVES: The objective of this study is to make use of the biochemical and physiologic differences among the various species of Malassezia to gain an insight into the epidemiology and the risk factor associations of these yeasts with pityriasisversicolor and seborrheic dermatitis in this part of our country, known for its hot and humid climate, which favours the growth of these yeasts and also to determine the antifungal susceptibility of the isolates to the commonly used azoles and amphotericin B. MATERIALS AND METHODS: This study was done at Madras Medical College, Chennai for a period of one year involving 100 clinically diagnosed cases of Malassezia infections, of whom 73 had pityriasisversicolor and 27 had seborrheic dermatitis. Skin scrapings from the lesional sites were collected using strict aseptic precautions and processed bystandard microbiological methods. Christensen’s urease medium with the addition of Tween compounds was used for antifungal susceptibility testing of the Malassezia isolates to fluconazole, itraconazole, ketoconazole, voriconazole and amphotericin B. RESULTS: Pityriasisversicolor commonly occurred in the 20 – 29 years age group (42.5%) and seborrheic dermatitis in the 40 -49 years age group (44.5%). Males were affected more commonly than females with both PV (72.6% males) and SD (74% males). Majority of the PV patients presented with lesions on the back (50.7%). Face and scalp (63%) were the common sites involved in SD. Majority of PV patients had hypopigmented lesions (63.1%). The overall culture positivity rate was 70%, the yield being higher with PV lesions. Among the PV cases, 92.6% of the hyperpigmented lesions were culture positive. M. globosa was the most common species isolated in PV and SD. Low MIC ranges and low MIC50 values of < 1 μg/ml were noted with amphotericin B, ketoconazole and itraconazole for most of the Malassezia species. CONCLUSION: Culture is an important step in the diagnosis of Malasseziainfections due to interspecies variability exhibited by Malassezia species in the etiological role in different geographical areas and differences in their susceptibility patterns to antifungal agents. Culture and antifungal susceptibility testing in the management of Malassezia infections will lead to a better targeted approach, reducing the cosmetic concerns, chronicity and recurrences associated with these infections.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Isolation of Malassezia Species ; Clinically Diagnosed Cases ; Pityriasis Versicolor ; Seborrheic Dermatitis ; Antifungal Susceptibility ; Isolates.
Subjects: MEDICAL > Microbiology
Depositing User: Punitha K
Date Deposited: 23 May 2018 02:47
Last Modified: 27 May 2018 04:35

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