KOH wet mount versus cellophane strip without mounting medium for rapid diagnosis in superficial mycoses

Abstract

Context: Diagnosis of superficial mycoses in clinically doubtful cases relies on demonstration of fungal elements on a 10% potassium hydroxide (KOH) slide mount which takes 30 min to 2 h. Rapid results will lead to reduced time to diagnosis. Aims: A comparative study of conventional 10% KOH wet mount against the cellophane strip method without a mounting medium under bright-field and phase-contrast microscopy was aimed to determine the comparative efficacy of these methods in demonstrating fungal elements of superficial mycoses. Settings and Design: The study was conducted at a skin center of a tertiary care hospital between November 2019 and January 2020. Material and Methods: One hundred and fifty consecutive clinically suspect cases of superficial cutaneous mycoses were examined. Skin scrapings for 10% KOH were collected with a blunt scalpel on one slide and examined half hour later. A cellophane strip collection of squames stuck onto another slide and examined directly by bright-field and phase-contrast microscopy. Statistical Analysis Used: Descriptive and inferential statistical analysis was carried out in the present study using SPSS 22.0, and R environment version 3.2.2 was used for the analysis of the data. Chi-square/Fisher’s exact test was used to find the significance of study parameters on categorical scale between two or more groups, nonparametric setting for qualitative data analysis. Fisher’s exact test was used when samples were very small. Results: The mean percentage positivity for fungal hyphae as seen on KOH mount was 76%, for cellophane tape 97.33%, and under phase-contrast microscopy 97.33%. Pityriasis versicolor was detected by all three methods (100%). Tinea corporis had the least positive result on KOH mount. Conclusion: Cellophane strip method without a mounting medium adequately demonstrates fungal elements on light microscopy.