{'fraction_non_alphanumeric': 0.02861704740849914, 'fraction_numerical': 0.020265291083271922, 'mean_word_length': 5.067809239940387, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 1, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Recognition of Dermatophytes by Dermatophyte Test Medium

The dermatophytes are a group of keratinophilic molds specialized to grow on the non living keratinized cells of the outer epidermis (stratum corneum), hair and nails of humans and lower animals. Dermatophytosis is a communicable skin disease affecting the skin, hair and nails. There are three closely related genera of dermatophytes : Trichophyton, Microsporum and Epidermophyton. The classic form of this mycosis is ringworm, a circular lesion with an active border, inflammation, pruritus and scaling. Dermatophytosis are among the most widespread and common superficial and cutaneous fungal infections in humans. International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 5 Number 10 (2016) pp. 1125-1129 Journal homepage: http://www.ijcmas.com


Introduction
In 1969, Taplin and co-workers developed a selective, indicator and differential dermatophyte test medium to provide a simple and rapid method for the detection and presumptive identification of dermatophytes from soldiers with ringworm infections during Vietnam war.
The dermatophytes are a group of keratinophilic molds specialized to grow on the non living keratinized cells of the outer epidermis (stratum corneum), hair and nails of humans and lower animals. Dermatophytosis is a communicable skin disease affecting the skin, hair and nails. There are three closely related genera of dermatophytes : Trichophyton, Microsporum and Epidermophyton. The classic form of this mycosis is ringworm, a circular lesion with an active border, inflammation, pruritus and scaling. Dermatophytosis are among the most widespread and common superficial and cutaneous fungal infections in humans.
The purpose of the study is to determine the clinical variants, their etiological agents and to compare Sabouraud dextrose agar (SDA) and dermatophyte test medium (DTM) for primary isolation of dermatophytes from one hundred clinically suspected cases of dermatophytoses. The culture was done in SDA and DTM and dermatophytes characterization were made by slide culture, urease test and hair perforation test. Among the dermatophytes isolated, the commonest was Trichophyton rubrum (55.22%) followed by Trichophyton mentagrophytes (34.33%) and Epidermophyton floccosum (10.45%). Majority of the patients had tinea corporis (31.43%) followed by tinea cruris (19.40%). The rate of culture positive by SDA and DTM were 65% and 67% respectively which shows no significant difference between the two media for primary isolation of dermatophytes. The present study shows DTM is good for isolation and early recognition of dermatophytes because of a distinct color change in the medium within two weeks time however, standard media such as SDA is required for species identification.

Article Info
Hence, the present study was undertaken to determine the clinical variants of dermatophytes and their etiological agents and to compare SDA and DTM for their isolation.

Materials and Methods
This prospective study was carried out in the Department of Microbiology in collaboration with the Department of Dermatology, Regional Institute of Medical Sciences (RIMS), Imphal, Manipur over a period of one year. A total of one hundred specimens were collected from the clinically suspected cases of derrmatophytic skin infections from the patients attending the inpatient and outpatient Department of Dermatology, RIMS, Imphal, Manipur. Samples were collected aseptically and transported in a sterile black paper to avoid exposure to moisture and prevent the growth of contaminants. The samples were screened for the presence of fungal hyphae by 20% KOH wet mount examination.
Commercially available DTM was used from TITAN BIOTECH Limited, Bhiwandi, and Rajasthan (TM 083). The ingredients of this media are: soya peptone: 20g; agar : 10 g; phenol red : 0.29ml ; pH: 5.5±2 at 25°C, distilled water : 1L. The media was prepared according to manufacturers' guideline & DTM supplement (chloramphenicol, gentamicin and cyclohexamide) was added. The plates were clear and yellow-orange. SDA with cycloheximide and chloramphenicol was prepared according to the modified method of Eummon's in our media preparation lab. The SDA and DTM were inoculated in duplicate, one incubated at 25°C and another at 37°C for 3 weeks. SDA was taken as the standard and compared with DTM. The growth of dermatophytes in DTM at 25°C was observed as change in the colour of the medium to red within two weeks time but remains yellow in the presence of nonpathogenic fungi. Species identification is more accurately determined with SDA and were confirmed by gross morphology of growth, typical microscopic characteristics, supplemented with slide culture, hair perforation test and urease test.

Results and Discussion
The results of the findings were tabulated and the data's were analyzed. Out of one hundred samples collected, 57% were KOH positive and remaining 43% were negative. As far as screening in DTM culture media was concerned, 67 of them were positive (67%) showing an alkaline (red) reaction on DTM within 2 weeks time; the rest 33 cases were negative as indicated in table 1. Finally, the screened samples were subjected to culture in SDA media which yielded 65 positive results (65%). Comparisons of SDA and DTM for the primary isolation of dermatophytes was done as shown in table 2.
Most of the cases were in the age group of 21-30 years. The least being below 10 years. Males were more commonly affected than females having the ratio being 2.85:1. The maximum number of patients was seen in the months from May to October i.e., during the rainy hot and humid season. Dermatophytosis is among the most common dermatological conditions in tropical countries. In the present study, an attempt was made to determine the various clinical patterns of dermatophyte infections and to compare the SDA and DTM for their isolation. Culture is more reliable method of diagnosis than microscopic examination.
The results of culture can be positive even if direct microscopic examination is negative, but is more common for microscopic examination to be positive while culture is negative.
In the present study, the percentage of samples positive by direct microscopy was 57 whereas, the percentage of culture positive was 67. All the 67 culture +ve cases in DTM produce an alkaline (red) reaction within 14 days time. The red colour change after 14 days must be discarded because saprophytes can induce a similar colour change from this time on. The dermatophytes produce an alkaline (red) reaction on DTM through oxidative deamination, while most of the organisms that are capable of growing on DTM produce an acid reaction (yellow). Approximately, 98% of fungi producing an alkaline reaction on DTM medium are dermatophytes (Taplin et al., 1969). The present study shows that culture (67%) was more sensitive than microscopy (57%) in the diagnosis of dermatophytosis. Similar findings were supported by Singh et al, 2003;Sowmya et al, 2014.   The rates of culture positive by DTM were (67%) and by SDA were (65%) which shows no significant statistically difference between the two medium for the primary isolation of dermatophytes. Our findings correlated with other workers finding by Singh et al, 2003;Sowmya et al, 2014.
The present finding also shows that DTM is a good screening medium for the primary isolation and early recognition of dermatophytes from clinical specimens. Species identification is more accurately determined with SDA.
The commonest age group affected was 21-30 years. The least age group was below 10 years. Similar results were observed by Gujarathi et al, 1996. Males were commonly affected than females. Similar findings were supported by Gujarathi et al, 1996;Mohanty et al, 1998. Dermatophytosis was seen to occur more in hot and rainy season. Similar results were observed in the studies of Gujarathi et al, 1996. Most of the patients were not complicated. To conclude, DTM is a good screening medium for the selective primary isolation and early detection of dermatophytes from clinical specimens.