Isolation Identification and In Vitro Antifungal Susceptibility of Dermatophytes

Sowmya, N (2011) Isolation Identification and In Vitro Antifungal Susceptibility of Dermatophytes. Masters thesis, PSG Institute of Medical Sciences and Research, Coimbatore.

[img]
Preview
Text
200401211sowmya.pdf

Download (2MB) | Preview

Abstract

INTRODUCTION: Fungi are eukaryotic organisms, which multiply sexually and asexually by the production of spores. Medical interest in fungi has increased as more and more fungi are associated with pathogenic infections. Medical mycology is the study of epidemiology, ecology, pathogenesis, diagnosis and therapeutic modalities of fungal infections in human beings1. The incidence and prevalence of fungal infections is increasing in both developed and developing countries due to underlying predisposing factors such as immunocompromised situations, use of corticosteroids, immunosuppressive agents, anticancer drugs, HIV-positivity, etc1. The fungi can cause a wide variety of superficial and systemic infections. Superficial fungal skin infections are more common in the hot and humid climate in the tropical and subtropical countries like India. AIM OF THE STUDY: To study the prevalence and antifungal susceptibility pattern of dermatophytes isolated from clinical samples in Coimbatore. OBJECTIVES: 1. Identification and characterization of different species of dermatophytes from 300 clinically defined cases of ring worm infections based upon their morphological features studied by microscopic, culture and biochemical techniques. 2. Comparison of Sabouraud dextrose agar and Dermatophyte test medium for the primary isolation of dermatophytes from the clinical samples. 3. Performance of in vitro antifungal susceptibility using broth micro-dilution method (CLSI M38-A2) and determination of the MIC range of the clinically isolated dermatophytes. SUMMARY: 1. A total of 300 patients with suspected dermatophytosis were studied. 2. Skin, nail and hair samples from the above patients were collected under sterile precautions. 3. Microscopic examination (KOH mount) of the samples from these patients showed the presence of hyphal elements in 103 (34.33%). 4. All the samples were simultaneously inoculated in Sabouraud dextrose agar(SDA) and Dermatophyte test medium(DTM). Fungal growth was observed in 147 (49%) of the samples with 129 (43%) of them being dermatophytes and remaining 18(6%) were non-dermatophytic fungi. There was no statistically significant difference between the two medium (p< 0.01) in primary isolation of dermatophytes. 5. Clinically 39 (43.33%) cases of tinea corporis, 22 (24.44%) of tinea cruris, 12 (13.33%) of tinea pedis, 7 (7.77%) of tinea manum, 7(7.77%) of tinea capitis, and 3 (3.33%) of tinea facium were positive for dermatophytes. Similarly, 33(11%) nail samples and 6 (2%) of hair samples also showed dermatophytic growth. 6. Trichophyton mentagrophtes (38.75%) was the predominant fungi isolated followed by Trichophyton rubrum (27.13%). 7. One case of tinea corporis caused by Trichophyton kanei, an anthrophophilic species was reported in our study. There were no reports of isolation of this fungus in India earlier. 8. All the dermatophytes isolated in our study were subjected to antifungal susceptibility testing by broth micro dilution method proposed by Clinical Laboratory Standard Institute (CLSI M-38 A2. 2008). 9. Trichophyton mentagrophytes ATCC MYA-4439 was used as control in our study. 10. The antifungal agents used in the study were Amphotericin B (Himedia), Fluconazole (Himedia), Ketoconazole (Himedia), Ciclopirox (Sigma Aldrich), Terbinafine (Sigma Aldrich) and Griseofulvin (Sigma Aldrich). 11. The MIC for Trichophyton mentagrophytes in our study were as follows: Amphotericin B 0.5 – 8 µg/ml, Fluconazole 1 – 8 µg/ml, Ketoconazole 0.0313-1µg/ml, Ciclopirox 0.125-2µg/ml, Terbinafine 0.001-0.008µg/ml and Griseofulvin 0.25-0.5µg/ml. 12. Incase of Trichophyton rubrum, the MIC values were: Amphotericin B 2 – 8 µg/ml, Fluconazole 0.125 – 2 µg/ml, Ketoconazole 0.25 -1µg/ml, Ciclopirox 0.125-2µg/ml, Terbinafine 0.001-0.008µg/ml and Griseofulvin 0.25-0.5µg/ml. 13. For Trichophyton tonsurans the MIC values were Amphotericin B 1 – 8 µg/ml, Fluconazole 1 – 4 µg/ml, Ketoconazole 0.313 - 0.25 µg/ml, Ciclopirox 1-2µg/ml, Terbinafine 0.001-0.004 µg/ml and Griseofulvin 0.125-0.5µg/ml. 14. For Trichophyton ajelloi the MIC values were Amphotericin B 4 µg/ml, Fluconazole 1 µg/ml, Ketoconazole 1 µg/ml, Ciclopirox 0.5 µg/ml, Terbinafine 0.002 µg/ml and Griseofulvin 0.5µg/ml. 15. For Trichophyton violaceum the MIC values were Amphotericin B 2 - 4 µg/ml, Fluconazole 0.25 – 0.5 µg/ml, Ketoconazole 0.5 µg/ml, Ciclopirox 1 µg/ml, Terbinafine 0.004 µg/ml and Griseofulvin 0.25 – 1 µg/ml. 16. For Trichophyton equinum the MIC values were Amphotericin B 4 – 8 µg/ml, Fluconazole 2 µg/ml, Ketoconazole 0.25 µg/ml, Ciclopirox 0.5 -1µg/ml, Terbinafine 0.004µg/ml and Griseofulvin 0.25µg/ml. 17. For Trichophyton meginii the MIC values were Amphotericin B 4 – 8 µg/ml, Fluconazole 0.25 – 0.5µg/ml, Ketoconazole 0.25 µg/ml, Ciclopirox 2 µg/ml, Terbinafine 0.004µg/ml and Griseofulvin 0.25µg/ml. 18. For Trichophyton kanei the MIC values were Amphotericin B 4µg/ml, Fluconazole 4 µg/ml, Ketoconazole 0.5 µg/ml, Ciclopirox 1 µg/ml, Terbinafine 0.004 µg/ml and Griseofulvin 0.5 µg/ml. 19. For Microsporum gypseum the MIC values were Amphotericin B 0.5 -2 µg/ml, Fluconazole 2 - 4 µg/ml, Ketoconazole 0.25 - 0.5 µg/ml, Ciclopirox 0.125 - 1 µg/ml, Terbinafine 0.004 µg/ml and Griseofulvin 0.125 - 0.5 µg/ml. 20. For Microsporum ferrugineum the MIC values were Amphotericin B 4 µg/ml, Fluconazole 8 µg/ml, Ketoconazole 1 µg/ml, Ciclopirox 2 µg/ml, Terbinafine 0.5 µg/ml and Griseofulvin 0.008 µg/ml. 21. For Epidermophyton flocossum the MIC values were Amphotericin B 2 - 4 µg/ml, Fluconazole 1 - 2 µg/ml, Ketoconazole 1 - 2µg/ml, Ciclopirox 0.25 – 0.5µg/ml, Terbinafine 0.001 – 0.004µg/ml and Griseofulvin 0.5 - 1 µg/ml. 22. None of the isolates have showed abnormal MIC range (except for Amphotericin B) when compared to MIC of standard strain reported in literature. This suggests that all are susceptible to the antifungals used. However future studies are required to evaluate the effect of drugs upon clinical response.

Item Type: Thesis (Masters)
Uncontrolled Keywords: Isolation Identification, In Vitro Antifungal Susceptibility, Dermatophytes.
Subjects: MEDICAL > Microbiology
Depositing User: Subramani R
Date Deposited: 18 Jul 2020 16:57
Last Modified: 19 Jul 2020 13:14
URI: http://repository-tnmgrmu.ac.in/id/eprint/12536

Actions (login required)

View Item View Item