Changing Trend of Superficial Mycoses with Increasing Nondermatophyte Mold Infection: A Clinicomycological Study at a Tertiary Referral Center in Assam.

BACKGROUND: Superficial mycosis is the commonest infections affecting human globally. Though they do not cause mortality, their clinical significance lies in their morbidity, recurrence, and cosmetic disfigurement, thus creating a major public health problem. The infections are more prevalent in the tropical regions. The etiological agents are also seen to vary with time and geographical location. AIM: This study was carried out to find out the trend of superficial mycosis in Assam, along with a clinicomycological correlation.
MATERIALS AND METHODS: A total of 130 clinically diagnosed cases of superficial mycoses attending the outpatient department (OPD) of a tertiary hospital in Assam for a period of 1 year were taken up for the study. After taking the informed consent and a proper history, the clinical materials like skin scrapings, nail clippings, and infected hair were sent for mycological examination.
RESULTS: The infection was found to be more prevalent among males than females (M:F, 3:2) and among the farmers and laborers (24.61%). Tinea corporis was the commonest clinical type (21.5%). Among the fungal isolates, dermatophytes were the most frequent isolates (43.54%), out of which Trichophyton rubrum was commonest. nondermatophyte moulds like Fusarium, Aspergillus, Scopulariopsis, Trichosporon, and Penicillium spp. were isolated.
CONCLUSION: The epidemiology of fungal infection and the causative fungi is seen to vary geographically and with time. This study reflects the changing trend of fungal infection in the north eastern region with a high rate of isolation of nondermatophyte moulds as the causative agent.

Introduction

Superficial fungal infections are one of the commonest infections affecting humans. Although worldwide in distribution, these infections are mostly clustered in the tropical regions, the main reason being the hot and humid climate, which favors fungal infection. The epidemiological trends of superficial mycoses all over the Asia show that the commonest dermatophytes incriminated are Trichophyton rubrum and T. mentagrophyte.[1] Fungal infections have attracted the attention of physicians and microbiologists in recent years, due to the rising trend, attributed to various reasons like indiscriminate use of antibiotics, anticancer therapy, and immunodeficient diseases like AIDS. The epidemiological trend of infections is also seen to vary both with time and geographical location. The commonly encountered species are the dermatophytes, candida, malassezia species, and nondermatophytic moulds which seem to be on the rise. Though several reports on dermatophytosis are available from different parts of the country, there are only few reports on nondermatophytic fungi and yeast like fungi as causes of superficial mycoses along with dermatophytosis from this part of the country.

In the present study, we undertook a clinicomycological approach to find the profile of superficial fungal infections, among patients visiting a tertiary care center in north east India, correlating various demographic data, such as age, sex, and occupation with identification of the causative fungus using standard techniques.

Materials and Methods

A total of consecutive and consenting 130 clinically diagnosed cases of superficial mycosis infections attending the outpatient department of Dermatology during a period of 1 year were taken up for the study. For conducting the study, the ethical committee clearance was taken. Clinically diagnosed cases of fungal infections of the skin, hair, or nail, attending the Dermatology OPD of a tertiary care hospital in Assam within the period of study and patients willing to undergo the microbiological examination were included in the study. Patients previously treated for the same infection and patients unwilling to take part in the study were excluded. After a thorough history and clinical examination, the samples were collected from the cases which included skin scrapings, nail clippings, and hair samples. These were subjected to direct microscopic examination after preparing a KOH mount with Parker's ink. The samples were also inoculated for fungal culture in Sabouraud's dextrose agar with chloramphenicol and cycloheximide with or without olive oil overlay, and in dermatophyte test medium. To delineate nondermatophyte moulds as the primary pathogen of nail infection, the stringent criteria as recommended by Walshe and English were followed in the study.[2] Also, repeat culture was done to rule out contamination when nondermatophyte molds (NDMs) were detected.

Results

Out of the 130 cases taken up for the study, the clinical type most frequently encountered was Tinea corporis (21.5%) followed by Pityriasis versicolor (19.23%) and mixed features in 15.38% cases [Table 1].

Table 1

Age-wise and clinical type-wise distribution of infections

Clinical types	<10 yr	11-20	21-30	31-40	41-50	51-60	>60	Total cases
T. corporis	2	4	10	4	5	2	1	28 (21.5%)
T. cruris	0	4	6	4	2	0	1	17 (13.07%)
T. pedis	0	1	1	4	1	1	1	9 (6.92%)
T. faciei	0	2	3	0	0	0	0	5 (3.84%)
T. mannum	0	0	0	0	1	0	0	1 (0.76%)
T. capitis	2	0	1	0	0	0	0	3 (2.3%)
Onychomycosis	0	1	5	5	1	2	3	17 (13.07%)
P. versicolor	3	9	8	5	0	0	0	25 (19.23%)
Mixed feature	0	4	6	5	3	1	1	20 (15.38%)
Cut. candidiasis	0	0	1	3	0	1	0	5 (3.84%)
Total	7 (5.38%)	25 (19.23%)	41 (31.54%)	30 (23.07%)	13 (10%)	7 (5.38%)	7 (5.38%)

T.: Tinea, P: Pityriasis, Cut.: Cutaneous

The commonest age group was 21–30 years comprising of 31.53% cases followed by the 31–40 years age group which had 23.07% of cases [Table 1].

The prevalence was found to be higher among males (60.77%) as compared to females (39.23%). Certain infections like Tinea cruris showed higher rates of infection in males (n-M 15, F 2) On analyzing the data occupation wise, the highest infection rates were noted among the farmers and laborers (24.61%) followed by the housewives (20.77%) and service holders (20.77%).

Mycological analysis of the samples collected from the 130 cases showed fungal elements in KOH mount in 96.92% samples, while fungal culture was positive in 47.69% cases. All the samples that were positive by fungal culture were also KOH mount positive.

Of the fungal culture positive cases, dermatophytes were isolated in 43.54% cases and nondermatophyte molds were isolated in 14.51% cases Candida was demonstrated in 12.9% cases, while the remaining cases were those of Pityriasis versicolor, demonstrating Malassezia [Table 2]. The nondermatophytic molds were mostly isolated from cases of onychomycosis [Figure 1] and tinea pedis, [Figure 2] which included strains of Fusarium [Figure 3], Aspergillus [Figure 4], Penicillium, Scopulariopsis, and Trichosporon [Tables 3 and 4], Fusarium and Aspergillus being the commonest isolates.

Table 2

Number of cases and their sites showing KOH+ve and culture positivity

Sample taken from	Total cases	KOH +	Fungal culture Positive (62)*
			Dermatophytes	NDM
Skin	113	110	25	3**
Hair	0	0	0	0
Nail	17	16	2	6
Total	130	126 (96.92%)	27 (43.54%)	9 (14.51%)

**3 NDMs isolated from skin scrapings were from cases of T. pedis. *Dermatophytes and NDMs isolated in culture, comprised of 36 cases. In the rest of the fungal culture positive cases, the fungal isolates were those of Candida spp. (8) and Malassezia spp. (18)

Figure 1

Onychomycosis due to nondermatophyte mould

Figure 2

Superficial fungal infection over toe webs, soles, nails (T. pedis and onychomycosis)

Figure 3

Colony of Fusarium

Figure 4

Colony of Aspergillus

Table 3

Nondermatophytes isolated

NDM	Number
Penicillium	1
Scopulariopsis	1
Cladosporium	1
Trichosporon	1
Aspergillus	3
Fusarium	2

Table 4

Fungal strains isolated

Fungus isolated	T. corporis	T. cruris	T. pedis	T. faciei	T. capitis	T. mannum	Onychomycosis	Cutaneous candidiasis	Mixed feature	PV	Total
T. mentagrophyte	3	2	1	1	-	-	-	-	1	-	8 (12.9%)
T. rubrum	4	4	-	-	-	-	1	-	1	-	10 (16.12%)
Epidermophyton spp.	3	-		-	-	-	1	-	2	-	6 (9.67%)
Microsporum spp.	2	-	-	1	-	-	-	-	-	-	3 (4.84%)
Malassezia spp.	-	-	-	-	-	-	-	-	-	18	18 (29.03%)
Candida spp.	-	-	-	-	-	-	4	4		-	8 (12.9%)
NDM	-	-	1	-	-	-	5	-	3	-	9 (14.52%)
Total	12	6	2	2	0	0	11	4	7	18	62 (47.69%)

T: Tinea, PV: Pityriasis versicolor, T: Trichophyton, NDM: Nondermatophyte mold

Discussion

In this study, 130 cases were selected from the clinically diagnosed cases of superficial fungal infections, out of which fungal elements were seen by direct microscopy in KOH mount in 96.92% cases and culture was positive in 47.69% cases. Other studies from different parts of India show variable mycological positivity rates, ranging from 45.3% to 56.33%,[3456] which is consistent with our study. The high rate of fungal isolation may be due to the climatic and geographical variation as Assam experiences a hot and humid climate that highly favors fungal growth.

The infection rates were highest among the age groups involved in occupational and outdoor activities, i.e., the 21–30 and 31–40 years (31.53% and 23.07%, respectively) rather than the extremes of age. This finding is consistent with previous studies like that of Grover et al.,[7] Das et al.,[8] and Patel et al.[9] Moreover, the occupation-wise analysis showed that the farmers and laborers were mostly affected (24.61%). These findings on the variables of age and occupation were probably due to the increased exposure to fungal pathogens from the environment and increased perspiration, both of which predispose to fungal infection. The youngest case was a 9-month-old child with P. versicolor and an 11-month-old child with T. corporis, probably acquired from infected mother.

The males (60.77%) were more frequently affected than females (39.23%) rendering a male:female ratio of 1.5:1 which correlated with other studies.[469]

The commonest clinical pattern of infection was tinea corporis (21.5%) which is in corroboration with other studies conducted in various parts of India.[34] It was followed by P. versicolor (19.23%), mixed features (15.38%), T. cruris (13.07%), and onychomycosis (13.07%) respectively. The mixed features mostly included cases of T. corporis with T. cruris, T. pedis with onychomycosis and T. mannum with onychomycosis. Another study conducted in northeast India recorded such high rates of mixed features, i.e., 17.3%,[7] while a study from Orissa found even higher rates of such involvement comprising of 25% cases.[10] This is probably due to the fact that these geographical areas experience high heat and humidity that favor fungal growth, thus creating high infection rates. The incidence of onychomycosis has been found to be higher compared to previous studies conducted in other parts of India but studies in northeast like that of Grover et al.[7] and Sen et al.[4] have found similar incidence of 14.8% and 11%, respectively. This might suggest that onychomycosis is more prevalent in this region.

Among the fungal isolates, the most common were the dermatophytes (47.69% cases), followed by Malassezia (29.03% cases), Candida (12.9%), and NDM in 14.5% cases, respectively. NDM were isolated from cases of onychomycosis and a few cases of T. pedis.

A study on superficial mycoses in northeast India by Grover et al. found the dermatophyte isolates to be 38.68%, nondermatophyte moulds to be 33.01% and yeast to be 28.3% of the fungal isolates, which are comparable to our study.[7] Among the NDMs, the commonest isolate was of Fusarium followed by Aspergillus spp. Other NDMs detected were Cladosporium, Trichosporon, Penicillium, and Scopulariopsis. This study showed a higher isolation rate of NDMs from onychomycosis cases compared to previous studies conducted in other parts of India. However, studies from the same geographical region like that of Grover et al.[7] and Sarma et al.[11] have reported 33.01% and 11.5% isolation rates of NDMs [Table 5]. Another study in Chennai, on cutaneous mycoses, reported 6.6% cases to be caused by NDMs. One possible explanation can be the environmental variation, because both northeast India and Chennai experience a hot and humid climate that favors the growth of these pathogens. Also, previously NDMs were considered as contaminants and discarded, but not so nowadays.[2] Sharma et al. reported Fusarium spp. and Curvularia spp. as the commonest, isolated in 3.27% cases each, followed by Aspergillus (3.26%) and Penicillium (1.63%) respectively, which is comparable to our study. A study from Iran reported Aspergillus as the commonest isolate from the cases of onychomycosis caused by NDMs.[12]

Table 5

Showing NDM isolation rates in previous studies

Study	NDM isolated
Grover et al.[7]	33.01%
Sarma et al.[11]	11.5%
Kumar et al.[14]	6.6%
Present study	14.5%

In our study, Fusarium was isolated from both skin and nails in one patient with T. pedis and onychomycosis, and in another patient with T. pedis. Fusarium infection may mimic interdigital T. pedis and manifest as dry type of infections.[13] Reports of NDM causing skin infections in India were put forward by studies of Grover et al.[7] and Kumar et al.[14]

Limitations

When a study is taken up on any infectious disease the sample should be large. The other limitation is in the selection of cases; instead of taking all cases of superficial mycosis, the superficial mycosis cases of candidiasis and pityriasis versicolor cases could have been excluded to justify the changing trend of superficial mycosis.

Conclusion

The infections due to NDMs are on the rise, which were previously considered as contaminants. Though its primary pathological role in causing skin infections is not yet established, its role in causing nail infections is well known. However, further studies of longer duration with large sample size are needed to comment on present scenario of superficial mycosis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.