Indian Journal of Dermatopathology and Diagnostic Dermatology

ORIGINAL ARTICLES
Year
: 2022  |  Volume : 9  |  Issue : 2  |  Page : 54--58

A clinico-mycological study of dermatophytoses and their in-vitro sensitivity to antifungal drugs


Manjunath Kadnur1, Shishira R Jartarkar1, Girish Narayanaswamy2, Ashwath S Manoj Kumar1, Sheena Arora1, Thushara Balakrishnan2,  
1 Department of Dermatology, Venereology, and Leprosy, Vydehi Institute of Medical Sciences and Research Centre, Whitefield, Bangalore 560066, Karnataka, India
2 Department of Microbiology, Vydehi Institute of Medical Sciences and Research Centre, Whitefield, Bangalore 560066, Karnataka, India

Correspondence Address:
Shishira R Jartarkar
Department of Dermatology, Venereology, and Leprosy, No. 272, 8th Cross, 29th Main, HSR Layout, 1ST Sector, Bangalore 560102, Karnataka
India

Abstract

Background: There is an increase in the frequency of resistant and recurrent dermatophyte infections in India. We undertook a study to isolate the organisms in different clinical presentations and to study their sensitivity to clotrimazole, miconazole, fluconazole, and griseofulvin. Aims: The aim of this article was to study the clinico-mycological pattern of dermatophytes and their in-vitro sensitivity to commonly used antifungals. Objectives: The objectives were as follows: (1) to study the clinico-mycological patterns of dermatophytosis and (2) to study the in-vitro sensitivity patterns of culture isolates to clotrimazole, miconazole, fluconazole, and griseofulvin. Materials and Methods: A total number of 48 patients were included in the study. The study period was from August 2019 to February 2021. Skin scrapings and nail clippings were inoculated in Sabouraud dextrose agar. Isolates were identified based on gross colony characteristics and microscopic morphology of their micro- and macroconidia and accessory structures. The isolates were then transferred to sterile distilled water in vials and stored. The clinical isolates stored in the stock solution were subcultured on to Potato dextrose agar. Then, the antifungal disks and Griseofulvin E strip were applied on to the plates. The zones of inhibition around the disks were measured and recorded. In the case of E strip, the minimum inhibitory concentration value is read from the scale in terms of µg/mL, where the ellipse edge intersects the strip. Results: The total number of cases included were 48. Commonest clinical presentation was co-occurrence of Tinea cruris and corporis (33%). Trichophyton mentagrophytes was isolated in 56% of cases. Isolates showed highest sensitivity to clotrimazole (87.5%) followed by miconazole (60.4%). Only 8.3% were sensitive to fluconazole and 37.5% were sensitive to griseofulvin. Conclusion: T. mentagrophytes is the causative organism in significant numbers of dermatophytic infections. Though broth dilution is the standard method for sensitivity assay of dermatophytes, disk diffusion method could become a more simple alternative.



How to cite this article:
Kadnur M, Jartarkar SR, Narayanaswamy G, Manoj Kumar AS, Arora S, Balakrishnan T. A clinico-mycological study of dermatophytoses and their in-vitro sensitivity to antifungal drugs.Indian J Dermatopathol Diagn Dermatol 2022;9:54-58


How to cite this URL:
Kadnur M, Jartarkar SR, Narayanaswamy G, Manoj Kumar AS, Arora S, Balakrishnan T. A clinico-mycological study of dermatophytoses and their in-vitro sensitivity to antifungal drugs. Indian J Dermatopathol Diagn Dermatol [serial online] 2022 [cited 2022 Nov 26 ];9:54-58
Available from: https://www.ijdpdd.com/text.asp?2022/9/2/54/359770


Full Text



 Introduction



Dermatophytoses is one of the most common dermatoses. Though not a serious disease, it significantly affects quality of life.[1],[2] A simple and easily treatable condition a few years ago has become one of the most commonly discussed topics for its recent increase in prevalence, recurrence, and resistance to treatment. These changes in the behavior of the disease could be due to the host factors, environmental factors, change in the species, and resistance to antifungal agents. In our study, we attempted to make a correlation of clinical features with culture pattern and also to identify the sensitivity pattern of the culture isolates to clotrimazole, miconazole, fluconazole, and itraconazole.

 Materials and Methods



All clinically suspected cases of dermatophytoses visiting dermatology OPD in our institute whose KOH mount was positive were included in the study. Those on immunosuppressants and topical and systemic antifungals in the last 1 month were excluded. A total number of 48 patients were included.

A detailed history including demographics, recurrences, previous treatment, etc. was taken. A detailed physical examination was done. Sample like scrapings of skin, nail clippings, and hair clippings was taken for KOH mount.

All samples (skin scrapings and nail and hair clippings) which showed fungal elements on KOH mount were inoculated on to Sabouraud dextrose agar (SDA) plate under aseptic precautions and incubated at 25°C for 2–3 weeks. Isolates were identified based on gross colony characteristics and microscopic morphology of their micro- and macroconidia and accessory structures. The isolates were then transferred to sterile distilled water (DW) in vials and stored.

Antifungal susceptibility testing

Antifungal susceptibility testing was done for the clinical isolates using disc diffusion method and E strip method. Paper disks containing clotrimazole (10 mcg), miconazole (30 mcg), and fluconazole (10 mcg) from Hi Media were used in the disk diffusion method to evaluate the in-vitro activity of the antifungal agents by measuring the mean diameter of inhibition around the disks. Griseofulvin E strip (0.002–32 mcg/mL, Hi Media) is used for calculating the minimum inhibitory concentration (MIC) of the drug [Table 1].{Table 1}

The clinical isolates stored in the stock solution were subcultured on to Potato dextrose agar to enhance sporulation, and inoculum was prepared using colonies containing mixture of mycelia and conidia. The inoculum was spread evenly on the surface of 10 cm Petri dishes containing SDA medium and exposed to air dry. Then, the antifungal disks and Griseofulvin E strip were applied on to the plates, after which the plates were incubated at 25°C for 5–10 days. The zones of inhibition around the disks were measured and recorded. In the case of E strip, the MIC value is read from the scale in terms of µg/mL, where the ellipse edge intersects the strip. Criteria of susceptibility and resistance of antifungal disks were measured according to manufacturers’ guidelines.

Statistical analysis

Data were entered in MS Excel and analyzed using SPSS version 19.

 Results



The total number of cases included were 48. Males were 34 and females 14.

Mean age of the patients was 35 years. Mean duration of the disease was 9 months.

The commonest clinical presentation was co-occurrence of Tinea cruris and T. corporis (33.3%), followed by T. cruris (20.8%) and by T. corporis (18.7%).

Trichophyton mentagrophytes was isolated in 56.2% of the cases. T. rubrum was isolated in 16.6% of the cases. Microsporum species accounted for 12.5%. [table 2], [graph 1]{Table 2} {Figure 1}

Drug sensitivity results

All dermatophytes combined showed highest sensitivity to clotrimazole (87.5%), followed by miconazole (60.4%).

Only 8.3% were sensitive to fluconazole and 37.5% were sensitive to griseofulvin. [Table 3], [graph 2]{Table 3} {Figure 2}

Among T. mentagrophytes which was the major species causing infection, 88% were sensitive to clotrimazole, 8% to fluconazole, 60% to miconazole, and 38% to griseofulvin.

 Discussion



Dermatophytoses is one of the most common infections of skin. Recently, there have been reports about the increase in the number of cases with extensive infection, resistant infections, and recurrent infections.[3],[4]

Most of the patients in our study were males (70.8%). The studies by Ghuse et al.[5] and Poojary et al.[6] also showed male preponderance. The reason for the male preponderance in our study could be due to the fact that most of our patients were immigrant manual laborers which was a male dominant group.

In our study, co-occurrence of T. cruris and T. corporis was the most common clinical presentation constituting 33%, followed by T. cruris 21% and T. corporis 19%. This is similar to the study by Poojary et al.,[6] in which co-occurrence of T. cruris and T. corporis was the most common presentation.

T. mentagrophytes was the most common organism which was isolated in 56% of the patients and T. rubrum in 17% of the patients. T. mentagrophytes was the most common organism in most of the clinical types.

Many studies from India show T. rubrum to be the dominant species.[7],[8],[9] However, of late studies are showing more contribution from T. mentagrophytes,[6],[10],[11] many a times contributing for more than 50% of the cases.[5],[12]

The shift in the species causing dermatophytoses could be one of the reasons for resistant and recurrent infections.

Among topical antifungals tested, 88% of the isolates were sensitive to clotrimazole and 60% of the isolates were sensitive to miconazole. Among systemic drugs tested, 38% of the isolates were sensitive to griseofulvin and 8% of the isolates were sensitive to fluconazole [Table 4] and [Table 5], [graph 3].{Table 4} {Table 5} {Figure 3}

These findings could not be compared with more studies as most of the studies used broth method for sensitivity testing.

Limitations

Small sample size

Other commonly used drugs such as terbinafine, itraconazole, luliconazole etc. could not be tested in our study.

 Conclusion



T. mentagrophytes is the causative organism in a significant number of dermatophytic infections. Most of the isolated dermatophytes are still sensitive to clotrimazole in vitro. Though broth dilution is the standard method for sensitivity assay of dermatophytes, disc diffusion method can become a more simple alternative. In this regard, further studies on disc diffusion method are needed.[13]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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