Laboratory-based epidemiological study of superficial fungal infections

Dermatophytosis continues to be a worldwide problem, constituting a large bulk of cases attending the dermatology outpatient's department in tropical countries. Variable climatic conditions and multiple etiological agents, whose individual prevalence varies with time, prompted an attempt to define the current pattern and etiologic prevalence in our locality, and compare them with earlier studies from different centers. Of consenting patients clinically diagnosed to have superficial fungal infections, 1975 were investigated in the laboratory. All the specimens collected from patient skin, hair or nails were subjected to direct microscopy examination in 10% potassium hydroxide (KOH) and fungal culture. Confirmed diagnosis was made only if specimen was KOH and/or culture positive. Male : female ratio was 1.65 : 1. Tinea corporis (21.4%), onychomycoses (14.7%) and tinea capitis (6.2%) were the most common laboratory-confirmed infections. Only 909 patients (47%) out of 1035 clinically suspected patients had evidence of fungal infection by either microscopy and/or culture. Of these 909 patients, 787 (86.5%) were both KOH and culture positive, 25 (2.7%) were KOH negative and culture positive, while 97 (10.6%) were KOH positive but culture negative. In 1051 patients (53%), no evidence of fungal infection was seen. Trichophyton rubrum was the most commonly isolated dermatophyte (55.2%) followed by Trichophyton mentagrophytes (19.6%) and Trichophyton tonsurans (2.9%). Candida sp. accounted for 16% of all isolates. Non-dermatophyte moulds (NDM) were isolated only in patients with onychomycoses. Our study revealed a male preponderance, tinea corporis as the commonest clinical type, and dermatophytes as the commonest mycological isolates, which is in agreement with earlier studies. Relying on clinical diagnosis alone without laboratory confirmation may result in overestimation of the problem as evidenced in other studies as compared to our study. Rarely reported NDM appear to be important etiological agents of onychomycoses.