NATURAL INFECTION IN LABORATORY ANIMALS DUE TO TRICHOPHYTON MENTAGROPHYTES IN INDIA

A Study of In vitro Antifungal Susceptibility Patterns of Dermatophytic Fungi at a Tertiary Care Center in Western India

Background:

Recent years have seen an alarming rise in the prevalence of recalcitrant and relapsing dermatophyte infections in India associated with lack of clinical response to standard antifungal regimens.

Aims and Objectives:

A study was undertaken to identify the antifungal susceptibility patterns of dermatophyte species isolated from lesions of dermatophytoses in patients examined at our center.

Materials and Methods:

A total of 85 patients with clinically diagnosed dermatophytoses were subjected to skin scrapings for potassium hydroxide mount (microscopic examination) and culture using Sabouraud's agar medium containing chloramphenicol and cycloheximide (incubated at 30°C). Antifungal susceptibilities [minimum inhibitory concentration-90 (MIC-90)] of the identified dermatophytes were tested for seven systemic and topical antifungal agents (terbinafine, griseofulvin, itraconazole, fluconazole, sertaconazole, ketoconazole, and clotrimazole) using Clinical and Laboratory Standards Institute broth microdilution method (M38-A).

Results:

Trichophyton rubrum (50%) and Trichophyton mentagrophytes complex (47.2%) were the two major species isolated. Isolates of both showed downy and granular forms (61.11%, 38.89% and 32.35%, 67.65%, respectively). The overall in-vitro susceptibility profiles (MIC-90 ranges in μg/mL) of the seven drugs for T. rubrum and T. mentagrophytes complex respectively were as follows: terbinafine (0.008–0256, 0.016–0.256), griseofulvin (0.03-1, 0.06–1), itraconazole (0.125-2, 0.25–2), fluconazole (0.125–1, 0.25–32), sertaconazole (0.03-1, 0.03-1), ketoconazole (0.06–1, 0.125–1), and clotrimazole (0.03–2, 0.06–1).

Conclusions:

This study indicates a rising proportion of T. mentagrophytes complex with increased proportion of granular form (T. mentagrophytes var. mentagrophytes). This study represents the current antifungal susceptibility profile of dermatophytic infections in a tertiary care medical center in western India with rising MICs to terbinafine and itraconazole.

Molecular strain typing of Trichophyton mentagrophytes (T. mentagrophytes var. interdigitale) using non-transcribed spacer region as a molecular marker

Background & objectives:

Dermatophytes are keratinophilic fungi that infect keratinized tissues of human and animal origin. Trichophyton mentagrophytes is considered to be a species complex composed of several strains, which include both anthropophiles and zoophiles. Accurate discrimination is critical for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Molecular strain typing renders an effective way to discriminate each strain. The objective of the study was to characterize T. mentagrophytes clinical isolates to sub-species level using molecular techniques and non-transcribed spacer (NTS) region as marker.

Methods:

Sixty four T. mentagrophytes clinical isolates were identified by phenotypic methods. These were subjected to polymerase chain reaction targeting three sub-repeat elements (SREs), TmiS0, TmiS1 and TmiS2 of the NTS region. Sequence analysis of internal transcribed spacer (ITS) region of different types was also done.

Results:

Strain-specific polymorphism was observed in all three loci. Totally, 13 different PCR types were obtained on combining all the three SREs loci. No variation was observed in the ITS region.

Interpretation & conclusions:

The study described the usefulness of molecular strain typing technique for the discrimination of the T. mentagrophytes isolates. This will help for the future explorations into the epidemiology of T. mentagrophytes and its complex.

Incidence of Keratinophilic Fungi from Selected Soils of Vidarbha Region of Maharashtra State, India

One hundred and fifty samples were collected from eleven districts of Vidarbha region of Maharashtra state and screened for the presence of keratinophilic fungi using hair baiting technique for isolation. Seventy-one isolates were recovered and identified. The cultures were identified using macro- and micromorphological features. Their identification was also confirmed by the BLAST search of sequences of the ITS1-5.8S-ITS2 rDNA region against the NCBI/Genbank data and compared with deposited sequences for identification purpose. Thirteen species of eight genera were isolated, namely, Auxarthron conjugatum (2.00%), Chrysosporium indicum (14.00%), Chrysosporium evolceanui (2.66%), Chrysosporium tropicum (4.66%), Chrysosporium zonatum (1.33%), Chrysosporium state of Ctenomyces serratus (3.33%), Gymnascella dankaliensis (1.33%), Gymnascella hyalinospora (0.66%), Gymnoascoideus petalosporus (0.66%), Microsporum gypseum complex (9.33%), Trichophyton mentagrophytes (2.00%), T. terrestre (3.33%), and Uncinocarpus queenslandicus (2.00%). This study indicates that the soils of Vidarbha region of Maharashtra may be significant reservoirs of certain keratinophilic fungi.

A compilation of published reports of mycoses in animals in India

The available published reports on animal mycoses in India and the fungal agents isolated from animal material are discussed. Among dermatophytes, the occurrence of Trichophyton verrucosum, T. mentagrophytes, T. rubrum, T. equimum, T. violaceum, T. simii, T. tonsurans, T. terrestre, T. ajelloi, Microsporum canis, M. gypseum and M. namum has been reported. Cases of aspergillosis, candidiasis, phycomycosis, rhinosporidiosis, epizootic lymphangitis, mycotic abortions and mycotic mastitis have been recorded in animals in this country. However, there is no report of histoplasmosis, sporotrichosis, blastomycosis and coccidioidomycosis among animals from India.