Chicago Sky Blue Stain, Calcofluor White Stain, and Potassium Hydroxide Mount for Diagnosis of Dermatomycosis.

Abstract

Objective: To evaluate Chicago Sky Blue (CSB) stain, Calcofluor white (CW) stain, and Potassium Hydroxide (KOH) mount for rapid diagnosis of dermatomycosis, using fungal culture as the gold standard.

Study design: Cross-sectional analytical study. Place and Duration of the Study: This study was conducted in the Department of Microbiology, Armed Forces Institute of Pathology / National University of Medical Sciences, Rawalpindi, Pakistan, from July 2023 to February 2024.

Methodology: Clinical specimens were collected from patients suspected of having dermatomycosis, including skin scrapings, hair, and nails. Each sample was divided into two parts. The first part underwent three microscopic techniques, namely 10% KOH mount, CSB stain, and CW stain. The presence and absence of hyphae were noted by each of the techniques. Second part was inoculated onto Sabouraud Dextrose agar (SDA) with and without antibiotics, along with Dermatophyte test medium (DTM). Culture plates were incubated at 30o C for four weeks. True-positive, true-negative, and diagnostic accuracy of the microscopy methods were calculated against fungal culture.

Results: Out of 121 patients, the majority were females constituting 65.3% (n = 79) while males were 34.7% (n = 42). The average age of participants was 32.98 ± 16 years. Diagnostic accuracy was 82.6% for CSB, 87.6% for CW stain, and 76.8% for 10% KOH mount.

Conclusion: CW stain proved to be superior to 10% KOH mount and CSB stain for rapid dermatomycosis diagnosis, with enhanced sensitivity and diagnostic accuracy. Both CW and CSB stains are recommended for laboratory use to improve reporting accuracy as compared to the conventional 10% KOH mount technique.

Key words: Calcofluor white, Chicago sky blue, Dermatomycosis, Fungal culture, Fungal hyphae.