Incidence and Epidemiology of Onychomycosis in Patients Visiting a Tertiary Care Hospital in India
Onychomycosis is a chronic fungal infection of the nails that is largely underdiagnosed in developing countries such as India due to poor health care facilities. In this study, we evaluated the nails of 134 patients with a clinical suspicion of onychomycosis using direct microscopy and fungal culture techniques. The majority of participants (47.8%) were older than 40 years. On both direct microscopy and fungal culture, 71.6% of participants were confirmed with onychomycosis. Among the cases confirmed by laboratory testing, distal lateral subungual onychomycosis was the most common clinical pattern observed, followed by proximal subungual onychomycosis (PSO), candidal onychomycosis (CO), and white superficial onychomycosis (WSO). We concluded that laboratory examination is of great importance in the diagnosis and identification of the underlying pathogen in patients with onychomycosis as well as in the selection of a suitable antifungal agent for treatment.
Practice Points
- Onychomycosis is a chronic fungal infection of the nails and represents 20% to 40% of all onycho-pathies worldwide.
- Apart from dermatophytes as etiologic agents, nondermatophyte molds and yeasts also can contribute to the disease.
- Categorization of onychomycosis clinically as well as mycologically will surely ensure better patient care.
- Avoiding certain habits (eg, walking with bare feet, wearing ill-fitting shoes, onychophagia) can decrease disease incidence.
Results
Of 134 clinically suspected cases of onychomycosis, 78 (58.2%) were from fingernails and 56 (41.8%) from toenails. Clinical diagnosis was confirmed in 96 (71.6%) cases by both fungal culture and direct microscopy but was confirmed by direct microscopy alone in only 76 (56.7%) cases. False-negative results were found in 23.9% (32/134) of participants with direct microscopy and 9.0% (12/134) with fungal cultures. The results of direct microscopy and fungal culture are outlined in Table 1. The study included 78 (58.2%) males and 56 (41.8%) females with a mean age of 44 years. Highest prevalence (47.8%) was seen in participants older than 40 years and lowest prevalence (11.9%) in participants younger than 20 years. In total, 32.8% of participants were farmers, 31.3% were housewives, 14.9% were students, and 20.9% performed other occupations. Disease history at the time of first presentation varied from 1 month to more than 2 years; 33.6% of participants had a 1- to 6-month history of disease, while only 3.7% had a disease history of less than 1 month at presentation. The demographic data are further outlined in Table 2.
Distal lateral subungual onychomycosis was the most prevalent clinical pattern found in 66 (49.3%) participants; fungal isolates were found in 60 of these participants. The next most prevalent clinical pattern was PSO, which was found in 34 (25.4%) participants, 12 showing fungal growth. A clinical pattern of CO was noted in 28 (20.9%) participants, 22 showing fungal growth; WSO was noted in 10 (7.5%) participants, 2 showing fungal growth.
Of 96 culture-positive cases, dermatophytes were the most common pathogens isolated in 56 (58.3%) participants, followed by Candida species in 28 (29.2%) participants. Nondermatophyte molds were isolated in 12 (12.5%) participants. The various dermatophytes, Candida species, and nondermatophyte molds that were isolated on fungal culture are outlined in Table 3. Of the 96 participants with positive fungal cultures, 30 (31.2%) were farmers working with soil, 28 (29.2%) were housewives associated with wet work, 16 (16.7%) were students associated with increased physical exercise from extracurricular activity, and 22 (22.9%) were in other occupations (Table 4).
