|Year : 2016 | Volume
| Issue : 2 | Page : 110-113
Clinicomycological study of dermatophytosis in a tertiary care centre
Nisha Majeed, Saritha Narayanankutty, Resmi Rajan, Ramani Bai Joseph Theodore
Department of Microbiology, Government Medical College, Trivandrum, Kerala, India
|Date of Web Publication||30-Nov-2016|
Department of Microbiology, Government Medical College, Trivandrum, Kerala
Source of Support: None, Conflict of Interest: None
Background: Fungal infections constitute a major health problem all over the world. Signs and symptoms induced by various dermatophytic infections are hardly distinguishable clinically from each other. Hence, characterisation by in vitro culture is required for the appropriate diagnosis and treatment as well as for studying the epidemiological characteristics in a region. Objectives: The objectives of this study are: (1) To isolate and identify dermatophytes affecting skin and nail. (2) To compare two different culture media, namely Sabouraud's dextrose agar (SDA, Himedia Laboratories, Mumbai) with Chloramphenicol and Actidione with dermatophyte test medium (DTM, Hi-Media Laboratories). Materials and Methods: This is a cross-sectional study in which patients attending the outpatient wing of the Department of Dermatology and Venereology, Government Medical College, Thiruvananthapuram, Kerala, India, with clinical features of dermatophytosis were included from March 2011 to February 2012. Skin and nail scrapings were subjected to direct microscopy by 10% potassium hydroxide (KOH), 40% KOH and cultured on SDA with Actidione (Hi-Media Laboratories) and DTM (Hi-Media Laboratories). Results: The total number of samples in this period was 150, of which 99 (66%) samples were positive by direct microscopy and 74 (49.33%) were positive by culture. The most common clinical type was tinea corporis 75 (50%) followed by tinea cruris 40 (26.67%). Out of the 74 isolates, Trichophyton rubrum 40 (54.05%) was the most common species followed by Trichophyton mentagrophytes 29 (39.19%), Microsporum gypseum three (4.05%), Trichophyton schoenleinii one (1.35%) and Epidermophyton floccosum one (1.35%).Nearly 86.1% of the dermatophytes were isolated on DTM within 5-10 days of inoculation whereas 47.05% were isolated on SDA within 10 days of inoculation. This was statistically significant with P < 0.0001 (χ2 = 22.43). Conclusion: DTM can be used as a rapid screening medium for the isolation and identification of dermatophytes compared to SDA with Actidione. However, DTM is inferior to SDA with Actidione in the identification of dermatophyte species.
Keywords: Dermatophytes, dermatophyte test medium, Sabouraud′s dextrose agar with Actidione, tinea
|How to cite this article:|
Majeed N, Narayanankutty S, Rajan R, Theodore RB. Clinicomycological study of dermatophytosis in a tertiary care centre. J Acad Clin Microbiol 2016;18:110-3
|How to cite this URL:|
Majeed N, Narayanankutty S, Rajan R, Theodore RB. Clinicomycological study of dermatophytosis in a tertiary care centre. J Acad Clin Microbiol [serial online] 2016 [cited 2017 Jun 24];18:110-3. Available from: http://www.jacmjournal.org/text.asp?2016/18/2/110/194939
| Introduction|| |
Infections caused by dermatophytes (dermatophytosis) are one of the earliest known fungal infections of humanity and are very common throughout the world. Dermatophytosis has been reported to be encouraged by hot and humid conditions and poor hygiene and occurs throughout in the tropical and temperate regions of the world. Dermatophytes are pathogenic fungi that have a high affinity to keratinised structures such as skin, nails or hair, causing superficial infections. A single species may be involved in several disease types, each with its distinctive pathology. Dermatophytosis is the colonisation of the keratinous tissues by a dermatophyte. The disease resulting from such colonisation is a consequence of the host's response to the metabolic products of the dermatophyte. The severity of the disease depends on the strain or the species of the dermatophyte and the susceptibility of the host to that fungus. At present, there are 42 species of dermatophytes classified into three genera - Trichophyton, Microsporum and Epidermophyton. The common virulent pathogens are Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton tonsurans, Trichophyton violaceum, Microsporum audouinii, Microsporum gypseum, Microsporum canis and Epidermophyton floccosum. Although common, the precise size of the problem defies measurement. Very often, the clinical presentation is confused with other skin disorders, making laboratory diagnosis and confirmation necessary by direct microscopy and culture.
| Materials and Methods|| |
Patients seeking medical advice at the dermatology outpatient department of Government Medical College, Thiruvananthapuram, with clinical features suggestive of dermatophytosis and not on antifungal therapy were included in this study. The study was conducted over a period of one year from March 2011 to February 2012. The study population included consecutive patients, diagnosed clinically as having dermatophytosis. Skin and nail scrapings collected were first subjected to potassium hydroxide (KOH) wet mount examination (10% KOH for skin, 40% KOH for nail). The rest of the specimen was cultured on Sabouraud's dextrose agar (SDA) with Chloramphenicol and Actidione (Hi-Media Laboratories) and dermatophyte test medium (DTM; Hi-Media Laboratories). Duplicate culture tubes were inoculated and incubated at room temperature for four weeks. The growth in DTM (Hi-Media Laboratories) resulted in colour change of medium from yellow to red due to the presence of phenol red indicator and production of alkaline by-products. The growth was further studied for morphology of colony, rate of growth and typical microscopic morphology (macroconidia and microconidia). Further, morphology was confirmed by slide culture. Speciation was done based on microscopic morphology, hair perforation test and urease test.
| Results|| |
Among 150 patients, 80 (53.3%) were males and 70 (46.6%) were females bringing out a slight male preponderance. The peak incidence of dermatophytosis was seen in the age group of 31-40 years (33.33%). A total of 113 (75%) patients belonged to the low socioeconomic status. Occupational profile of the patients showed that the largest group consisted of manual labourers (30%) followed by students (26.67%). The most common clinical type was tinea corporis 75 (50%) [Table 1].
[Figure 1] shows the sex distribution of clinical types of dermatophytosis.
Direct smear positivity (KOH) was found in 99 (66%) samples whereas culture positivity was found in 74 samples (49.33%). Out of the 150 samples, 54 (36%) were positive by both direct microscopy and culture and 45 (30%) were positive by direct microscopy alone [Table 2].
|Table 2: Comparison of culture positivity and potassium hydroxide positivity |
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T. rubrum 40 (54.06%) was the most common species isolated followed by T. mentagrophytes 29 (39.18%) [Table 3]
Out of 38 culture-positive isolates of tinea corporis, T. rubrum 22 (58%) was the most common species [Figure 2].
|Figure 2: Correlation between clinical and mycological types of dermatophytosis|
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In our study, 72 (97.3%) dermatophytes were isolated from DTM (Hi-Media Laboratories). Three isolates of T. rubrum and four isolates of T. mentagrophytes did not grow on SDA with Actidione (Hi-Media Laboratories) [Table 4].
|Table 4: Analysis of isolates on Sabouraud's dextrose agar and dermatophyte test medium |
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In the present study, 62 (86.1%) isolates were isolated from DTM within 5-10 days of incubation whereas 32 (47.05%) dermatophytes were isolated from SDA with Actidione during the same period [Table 5].
|Table 5: Comparison of rate of dermatophyte growth on Sabouraud's dextrose agar and dermatophyte test medium |
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| Discussion|| |
In this study, the highest incidence of dermatophytosis was found in the age group of 31-40 years and in males. The probable reason for this is excessive sweating due to excessive physical activity, in addition to the tropical climatic conditions. This finding correlated with the studies of Hanumanthappa et al., and Madhavi et al.
The most common clinical type was tinea corporis. This is in accordance with the studies of Sharma et al. and Kumar et al. (2007). Tinea corporis was more in females. In our study, tinea cruris was more common in males. This finding is supported by studies conducted by Singh and Beena and Peerapur et al.
Out of the 150 samples, 54 (36%) yielded positive results by direct microscopy and culture and 45 (30%) yielded positive results in direct microscopy alone. About 20 (13.33%) were culture positive alone and 31 (20.6%) were negative for direct microscopy and culture. This is in accordance with the studies of Hanumanthappa et al., Singh and Beena, and Bhargavi. Patel et al. in their study reported that the isolation rate was more by direct microscopy using KOH preparation (62.12%) than culture (29.29%) compared to the rates of 7% to 49% by culture in other studies. Nearly 2.53% of the specimens were positive by culture alone and 70 (35.35%) were by direct microscopy alone, highlighting the importance of both direct microscopy and culture in the definitive diagnosis of fungal infection.
T. rubrum was the most common species isolated followed by T. mentagrophytes. The other less common isolates were M. gypseum, Trichophytonchoenleinii and E. floccosum. These findings are in accordance with the findings of Kumar et al. (2007), Patel et al. and Hanumanthappa et al. Georg has suggested that both the predominantly chronic nature of the infection and the adaptation of the dermatophyte to the human skin can explain the higher predominance of T. rubrum.
In this study, it could be noted that 86.1% of the dermatophytes were isolated on DTM (Hi-Media Laboratories) within 5-10 days of inoculation whereas 47.05% were isolated on SDA within 10 days of inoculation. This was statistically significant with P < 0.0001 (χ2 = 22.43). In the case of SDA with Actidione, the colony characteristics could be well made out. The comparative evaluation of the isolation of dermatophytes on SDA and DTM has been reported by Singh and Beena. In their study, they found SDA to be 96.55% and DTM to be 98.27% effective in the isolation of dermatophytes while Yavuzdemir found no significant difference in the isolation rates of these media. The effectiveness of SDA was 93.5% and that of DTM was 95.4% in his study of 225 samples. Our study had found an isolation rate of 97.3% for DTM and 91.8% for SDA with Actidione. Species-level identification was not possible with growth on DTM on primary isolation as conidial production was low on DTM, which is required for identification. For identification, it was required to subculture further on to SDA with Actidione.
| Conclusion|| |
The present study gives an insight about the etiological agents of dermatophytosis in this part of Kerala. Diagnosis of these infections requires proper laboratory aid. DTM is a good screening medium in the laboratory diagnosis of dermatophytosis compared to SDA with Actidione. However, DTM is not a preferable medium for the identification of dermatophytes.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]