A Clinicomycological study of Onychomycosis, its Antifungal Susceptibility Pattern and Rapid Detection of Trichophyton Genus from Nail Samples by PCR Analysis of 18S rRNA Gene Internal Transcribed Spacer Region.

INTRODUCTION : Fungi are ubiquitous, capable of colonizing almost any environment. The cutaneous infections in man include a wide variety of diseases in which the integument and its appendages – the hair and nail are involved. The word onychomycosis in general describes fungal infection of the nails with the causative agent being dermatophytes, nondermatophytic moulds and yeasts. Onychomycosis is a common condition affecting 5.5% of the population worldwide and represents 20-40% of all onychopathies and about 30% of cutaneous mycotic infection. Onychomycosis a common nail ailment associated with significant physical and is psychological morbidity. Increased prevalence in recent years is attributed to enhanced longevity, increase in comorbid conditions such as diabetes, avid sports participation and emergence of HIV. The prevalence rate of onychomycosis is determined by age, predisposing factors social class, occupation, climate , living environment and frequency of travel. In spite of improved personal hygiene and living environment, onychomycosis continues to persist and spread. Onychomycosis is not self-healing and may be a reservoir of more widespread fungal lesions of the skin. AIMS AND OBJECTIVES : 1. To study the prevalence of onychomycosis and its aetiological agents. 2. To find out the commonest agent responsible for onychomycosis. 3. To study the correlation of fungal isolates and the clinical manifestations. 4. To detect Trichophyton genus directly from nail samples by PCR. 5. To compare the results of conventional methods and PCR. 6. To determine the antifungal susceptibility of the isolates by microbroth dilution. 7. To determine the antifungal susceptibility of filamentous fungi by E test method. 8. To compare the results of microbroth dilution and E test method for filamentous fungi. CONCLUSION : The nail changes are not always a reliable marker for predicting the causative organism, and relying only on the clinical manifestation in the diagnosis is often misleading since only 51.33% of the suspected case of onychomycosis showed positivity by culture. Knowing the exact pathogen is important and has implication in therapy and prognosis. Our study highlights the need for microbiological confirmation in case of onychomycosis. There is a relatively high incidence of fingernail onychomycosis of DLSO pattern in middle aged men. Although regional and temporal variability exists among the microorganisms that are pathogenic in onychomycosis, dermatophytes still remain the predominant etiological agents. Terbinafine has been observed to be the potent drug active against dermatophytes. The environmental ecology changes from time to time and nondermatophytes which were previously considered as contaminants are now emerging as primary pathogens and their definitive diagnosis can be done only on the basis of stringent criteria . The non dermatophytes are responsible for 35.06% of cases of onychomycosis. Voriconazole and amphotericin - B have been observed to be effective against nondermatophytes. Candida albicans are more common among housewives who were exposed to heavy wet workload which helps the yeast to flourish. Direct microscopy and culture are necessary for all suspected cases and can be used in a laboratory with a minimal infrastructure. Each laboratory should set up consecutive cultures from consecutive nail scrapings. Among conventional methods KOH with DMSO is more sensitive than culture. The changing profile of human dermatoses has been observed of late which requires improved diagnostic methods for identification. So newer diagnostic methods are need of the hour not only for accurate diagnosis but also for post therapeutic strategies. The application of PCR directly to clinical samples along with conventional methods will help to detect the causative agent early and accurately and helps not to miss other fungi which would permit prompt and targeted intiation of antifungal therapy. The E test can be considered a good alternative. In addition, education of patients about the importance of foot and nail care and earlier treatment of dermatophytic skin infections should be considered as essential components in the management of these patients