الفهرس 
? Epidemiology of superficial fungal infectionsOnly 14 pages are availabe for public view
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Abstract
Superficial fungal infections usually involve the skin, hair and nails. The group of fungi most commonly responsible for causing infection of these sites are known as the dermatophytes and include the genera, Trichophyton, Microsporum, and Epidermophyton. The infection they cause is commonly known as tinea or ringwom, with the full name relating to the site of infection. Superficial fungal infections can also commonly be caused by candida species, which are yeasts. The most common candida species causing infection is candida albicans.
It is sometimes difficult to rely completely on results of direct microscopic examination with KOH to establish the diagnosis of different fungal skin infection as it lacks sufficient sensitivity. However it’s highly efficient as a screening technique. Culture on the specific media of dermatophytes will ensure the diagnosis reaching to the species level and sometimes to strain level, however it may be time consuming, costly, different culture media are needed for proper identification, in addition to the presence of special skills and experiences as the morphological character of some species are atypical. However, the culture still remains the standard procedure.
When clinical presentation is atypical dermatophytes are identified to species level by morphological features using conventional morphological techniques such as macroscopic examination of large, mature colonies and different culture techniques. Further identification characteristics include nutritional requirements (such as vitamin and amino acid utilization), urease production, in vitro hair perforation, Bromocresol purple-milk solids-glucose medium, etc.
In our study, our aim was to investigate whether the strategy of serial repetition of routine direct microscopy examination and fungal culture will improve diagnosis efficacy of superficial fungal infections and reduce the possibility of false negative results or not.
Seventy five Egyptian patients with superficial fungal infections were subdivided into 5 groups. Each group consists of 15 patients as follows:
Group I: Scaly ring worm.
Group II: Tinea cruris.
Group III: Tinea pedis.
Group IV: Glabrous skin fungal infection.
Group V: Onychomycosis.
Three successive scrapings from the lesions were collected with an interval that varies from 2 to 5 days between each sample. During this interval the patients were not using any antifungal therapy and the suspected lesions should not be scraped.
The first samples were analyzed using microscopic examination and culture growth. Specimens were mounted in 20% KOH for 30 minutes and examined under the low (x10) and high (x40) power lenses of the light microscope. Every sample was cultured on 2 Sabouraud chloramphenicol cycloheximide agar and 2 Dermasel chloramphenicol cycloheximide. The tubes were inoculated with finely divided pieces from the samples and incubated at 30°C for up to 4 weeks. The tubes were examined twice weekly for evidence of growth.
After getting the results of the cultures of the first samples, we performed microscopic examination and culture growth of the second samples only for those samples which were negative in the first culture. Among the 75 mycological examinations there were only 50 positive diagnoses of superficial fungal infections, 36 by dermatophytes, 14 by yeasts and only 1 by moulds in the first analysis. One Tinea pedis sample showed a mixed infection of a mould (fusarium) and yeast (trichosporon). In the second analysis (n=29), 4 samples that were negative in the first analysis were positive in the second evaluation. These new positive diagnoses in the second mycological examination were by dermatophytes (3/4) and yeasts (1/4). The 25 mycological tests that were negative in the first and second tests were also negative in the third mycological analysis.
In conclusion, we found that serial repetition of direct microscopic examination and fungal culture does not improve superficial fungal infections diagnosis efficiency. This strategy of repetition can be done only when the clinical picture is highly suspicious of fungal infection to avoid misdiagnosis and submitting the patient to unnecessary or inefficient treatment.
Our recommendation is that serial repetition should be done only once as we found that no samples turned positive by the third analysis and this strategy of repetition should be followed with onychomycosis because multiple sampling possibly gives better access to nail-bed debris, because it becomes easier to collect an adequate specimen after the first or second nail scraping, favoring isolation of the fungus.