Isolation, Identification and Antifungal Susceptibility of Dermatophytes Isolated from Clinically Suspected Cases of Tinea Infections in Pakistan

Dermatophytosis or tinea is a type of cutaneous infection caused by keratinophilic fungi, infecting the skin, nails and hair. A correct diagnosis is important for epidemiological purposes and initiating appropriate treatment. An increase in the prevalence of fungal infection worldwide is due to abuse of antibiotics, immunosuppressive treatments and numerous medical conditions.

Aim: To isolate, identify, and examine the in-vitro antifungal susceptibility of dermatophytes in clinically suspected cases of tinea infections.

Methodology: After taking informed consent, we took 65 patients suspected of tinea infection and obtained samples from skin, hair and nail, under aseptic precautions, at Department of Microbiology, University of Health Sciences (UHS), Lahore, Pakistan. The identification of dermatophytes was performed using potassium hydroxide (KOH) mounts and culture on Sabouraud Dextrose Agar (SDA) and Dermatophyte Test Medium (DTM). The cultures were incubated at 30ºC for up to 4 weeks in case of SDA and 2 weeks in case of DTM. Lactophenol cotton blue (LCB) stain was used to identify the species morphologically. Susceptibility test was done by agar diffusion method using antifungal disks and zones of inhibition were measured.

Results: More females (55.38%) than males (44.61%) were observed in the study. Most of the cases belonged to the age categories of 1-10 years and 21-30 years. Tinea corporis was the most common clinical type found (27.69%) followed by Tinea capitis (21.53%) and Tinea cruris (12.30%).Trichophyton mentagrophytes was the commonest species isolated (32%) followed by Trichophyton violaceum (28%) and Trichophyton rubrum (12%). Terbinafine was seen to be the most effective drug against the isolates, followed by clotrimazole. Fluconazole showed least activity.

Conclusion: Fungal culture remains the gold standard in identifying the causative species. Terbinafine promises to be a potent antifungal, whereas fluconazole has low efficacy against such organisms. Disk diffusion method adopted for antifungal susceptibility is cost effective and easily performable in small laboratories not having an established mycology bench.