Isolates Of Trichophyton Mentagrophytes Research Articles

Inhibition of the growth in vitro of Trichophyton mentagrophytes, Trichophyton erinacei and Microsporum persicolor by miconazole and chlorhexidine

An agar dilution technique was used to assess the minimum inhibitory concentrations (MICs) of miconazole, chlorhexidine and a 1:1 combination of both agents for 9 isolates of Trichophyton mentagrophytes, 9 isolates of Trichophyton erinacei and 5 isolates of Microsporum persicolor. MICs of chlorhexidine did not vary significantly between the three dermatophyte species tested, but the MICs of miconazole alone and in combination with chlorhexidine for T. erinacei were significantly greater that those for T. mentagrophytes and M. persicolor. A synergistic drug interaction was noted with one isolate of T. erinacei and one isolate of M. persicolor. An additive effect was demonstrated for 13 isolates (5 T. mentagrophytes, 6 T. erinacei, 2 M. persicolor), and indifference was noted in 8 isolates (4 T. mentagrophytes, 2 T. erinacei, 2 M. persicolor). Although synergy was less often seen when compared with a previous study of Microsporum canis, the synergistic or additive effects seen with the majority (15 out of 23) of isolates studied in vitro provides a rationale for the combined use of miconazole and chlorhexidine in the adjunctive topical therapy of dermatophytosis caused by T. mentagrophytes, T. erinacei and M. persicolor.

Anti-Dermatophytic Activity of Some Indian Medicinal Plants

Objective: Anti-dermatophytic activities of 23 South Indian medicinal plant materials have been studied using five isolates of Trichophyton rubrum and four isolates of Trichophyton mentagrophytes obtained from the patients of Raja Muthiah Medical College & Hospital, India and compared. Materials and methods: Water and ethanol extracts were prepared and their minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined. Results and conclusion: Ethanol extracts of plants exhibited more activity than water extracts. Among 23 plants garlic showed least MIC & MFC. In addition, ethanolic extracts of 11 plants showed less than 11.5 mg/ml MFC against T. rubrum and 9 plants showed less than 11.5 mg/ml MFC against T. mentagrophytes .

Two arthroderma benhamiae isolates showing mitochondrial DNA type of Trichophyton verrucosum.

Two Trichophyton mentagrophytes isolates from skin lesions on a girl and her rabbit, which were identified as Arthroderma benhamiae by mating tests, were studied by mtDNA (mitochondrial DNA) analysis and sequencing of ITS (internal transcribed spacer) regions of nuclear ribosomal RNA genes. The mtDNA-RFLP (restriction fragment length polymorphism) patterns showed the two isolates to be T. verrucosum rather than A. benhamiae. The ITS sequence showed the isolates to be closer to A. benhamiae Americano-European race than to T. verrucosum and closer to T. verrucosum than to their mating partner A. benhamiae African race. These results suggest that there are three genetic types of A. benhamiae - an Americano-European type, an African type and a T. verrucosum type - and that T. verrucosum is an anamorph of A. benhamiae.

Soil dermatophytes in Madras, India, in relation to human ringworm.

A total of 269 soil samples collected from different habitats in Madras, India, were screened for the presence of dermatophytes by the hair-baiting technique. Three strains of Trichophyton mentagrophytes and 16 strains of Microsporum gypseum complex were isolated. These strains were subjected to the mating experiment. 2/3 soil isolates of Trichophyton mentagrophytes belonged to Arthroderma vanbreuseghemii (+) mating type, and 1/3 was Arthroderma vanbreuseghemii (-) mating type. Similarly 6/70 clinical strains of Trichophyton mentagrophytes isolated in our previous study also belonged to Arthroderma vanbreuseghemii (+) mating type. These 6 strains were isolated from severe cases of tinea capitis in children belonging to rural Madras. The teleomorphic and mating type homology between the clinical and soil isolates of T. mentagrophytes suggest that soil may act as reservoir for these organisms. The incompatible clinical strains of T. mentagrophytes var. interdigitale and A. vanbreuseghemii showed DNA homology, thereby establishing the epidemiologic link which supports the above findings.

Typing of Common Dermatophytes by Random Amplification of Polymorphic DNA.

Seventy-six clinical isolates of dermatophytes and 8 preserved strains of Arthroderma were investigated by random amplification of polymorphic DNA (RAPD) assay to determine the DNA types of common dermatophytes and find any relationships of DNA-based typing with morphology, teleomorphs, geographic origins and sites of human infection. It was found that each species showed a distinct DNA pattern, which can be used as an identification marker. Forty-two isolates of Trichophyton mentagrophytes were classified into 3 main types and intratype polymorphism was revealed with some primers. No simple relationship was found between DNA type and morphology, but the DNA types of strains were closely related to their geographic origins. The RAPD groups of Arthroderma benhamiae, A. vanbreuseghemii, A. gypsea and A. otae were distinctly different, whereas the 42 clinical isolates of T. mentagrophytes shared similar patterns with A. vanbreuseghemii. Among 30 clinical isolates of T. rubrum, 22 showed almost identical RAPD type, while the other 8 strains differed slightly in band patterns. T. rubrum exhibited great differences from A. benhamiae and A. vanbreuseghemii. In conclusion, RAPD provides a stable and reliable means of typing common dermatophytes, and is a powerful tool for dermatophyte identification and epidemiological study.

In vitro susceptibility of fungi to acyclic inhibitors of 2,3-oxidosqualene cyclases.

In the present study we determine the antifungal properties of two acyclic inhibitors of 2,3-oxidosqualene cyclases: 22,23-epoxy-2-aza-2,3-dihydrosqualene (EAS) and azasqualene alcohol (ASA). Fungistatic and fungicidal activity towards dermatophytes and other fungi involved in cutaneous and systemic infections was tested (48 isolates from 10 species). The tests were carried out by inoculating 10 microliters of mycelial homogenate in 1 ml of Sabouraud glucose liquid medium containing serial dilutions of 100 to 0.25 micrograms ml-1 of the substance. For each isolate, the minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of both compounds were determined. EAS was more active (MIC range 1.5-25 micrograms ml-1) than ASA (MIC range 3-50 micrograms ml-1). At the highest concentration tested, EAS also showed fungicidal action towards some isolates of Trichophyton mentagrophytes, T. terrestre, Epidermophyton floccosum, Microsporum canis and Scopulariopsis brumptii. The most sensitive species was T. mentagrophytes, the most resistant T. rubrum.

The proteolytic activity of strains ofT. mentagrophytesandT. rubrumisolated from tinea pedis and tinea unguium infections

To understand the significance of proteolytic enzymes in the pathogenesis of dermatophyte infections, we have studied the expression of proteolytic activity in vitro. Cultures were extracted after 1, 2, 3, 4 and 5 weeks of growth and the proteolytic activity measured by a peptide release assay using human stratum corneum as a substrate. Maximum activity was noted at 3 weeks which corresponded to the dissolution of the stratum corneum particles. Isolates of Trichophyton mentagrophytes and Trichophyton rubrum from 42 patients with tinea pedis or tinea unguium were established on 2% glucose peptone plates. Using the peptide release assay it was found that after 3 weeks culture, T. mentagrophytes showed higher activity that T. rubrum in tinea pedis (2044 +/- 1067 micrograms protein released h-1 mg-1, n = 13 compared to 828 +/- 614 micrograms protein released h-1 mg-1, n = 13). In tinea unguium, the values at 3 weeks were generally lower. Trichophyton mentagrophytes activity was 837 +/- 121 micrograms protein released h-1 mg-1 (n = 3) compared to 470 +/- 271 micrograms protein released h-1 mg-1 (n = 13) for T. rubrum. Thus, as well as a variation in activity between the two species, there appears to be a variation in site in terms of expression of activity.

A new keratinolytic proteinase from clinical isolates of Trichophyton mentagrophytes.

AbstractA new keratinolytic proteinase produced by each of three clinical isolates of Trichophyton mentagrophytes was found in culture filtrates containing human strarum corneum as a nitrogen source. The partially purified proteinase fraction exhibited serine proteinase‐like characteristics in spite of its weakly acidic optimum pH. The existence of a keratinolytic proteinase with enzyme activity under acidic conditions could be an important pathogenic element in dermatophytic invasion of weakly acidic healthy skin.

Inhibition of hyphal development in Trichophyton mentagrophytes arthroconidia by ketoconazole and miconazole.

In the presence of 0.5 mg/l ketoconazole and miconazole, arthroconidia from three isolates of Trichophyton mentagrophytes produced germ tubes, which continued to grow for 12 h before further elongation ceased. Lower concentrations reduced the rate of elongation, but did not halt the process. Higher concentrations had no greater effect than 0.5 mg/l. The inhibitory effect of ketoconazole was independent of time of addition of drug during the first six hours of germination. Ketoconazole inhibition was reversible after 12 h contact, whereas miconazole inhibition was not. Morphological effects of drug treatment were investigated by scanning electron microscopy. In the absence of imidazoles, hyphae were straight and regular; ketoconazole treated hyphae were short, irregular and branching; miconazole treatment produced extensive debris and spores forming within the hyphae were visible.

Comparison of the in vitro antifungal activities of ketoconazole and griseofulvin against clinical isolates of Dermatophytes.

Ketoconazole, a new imidazole derivative, and griseofulvin, are the two most valuable oral antimycotics for oral administration in the treatment of dermatophytosis. The antifungal properties of ketoconazole were compared in vitro with those of griseofulvin using a liquid microculture method and 68 clinical isolates of dermatophytes. Both drugs showed minimal inhibitory concentration (MIC) values of ≤5μg/ml for all isolates of Trichophyton rubrum. The MIC values of griseofulvin for 90% of Trichophyton mentagrophytes isolates ranged from 0.5 to 3μg/ml; the MIC values of ketoconazole for Trichophyton mentagrophytes ranged from 0.5 to 5μg/ml or greater. Microsporum species were 2.3-6.3 times more susceptible to griseofulvin than to ketoconazole; Epidermophyton floccosum was uniquely susceptible to both drugs.

Mating Behavior of 334 Japanese Isolates of Trichophyton mentagrophytes in Relation to Their Ecological Status

A mating study performed by crossing 334 Japanese isolates of Trichophyton mentagrophytes with + and - tester strains of Arthroderma simii, A. benhamiae and A. vanbreuseghemii revealed that T. mentagrophytes in Japan was a complex composed of the conidial states of A, vanbreuseghemii and the other asexual strains corresponding to T. interdigitale and a small number of the granulosum-asteroides form of which mating type was indeterminate. None of the isolates mated successfully with A, simii and A. benhamiae. Forty-nine isolates which successfully mated with A, vanbreuseghemii were further subclassified into 39 of the granulosum-asteroides form, three of the powdery form and seven of the persicolor form on the basis of the morphological differences in culture, The former one form was zoophilic in nature, while the latter two appeared anthropophilic in nature. These three forms differed from each other in their sexual reactivity, The granulosum-asteroides form consisted of + (80%) and - (20%) mating types, while the powdery form, the persicolor form and T, interdigitale were all of the + mating type, Differences in geographic distribution between + and - mating types were also elucidated for an epidemiological approach to this species complex.

The perfect state ofTrichophyton mentagrophytes

Growth of 21 granular isolates of Trichophyton mentagrophytes, singly and in various combinations on plates of sterilized soil, baited with horse hair, led to the development of fertile cleistothecia. Mating of monoascospore cultures showed that this organism is heterothallic. The ascocarps are characteristic of the genus Arthroderma, and the perfect state has been named A. benhamniae sp. nov. Die Kultur von 21 Trichophyton mentagrophytes-Isolaten in der granulären Wuchsform — einzeln und in verschiedenen Kombinationen in Schalen mit steriler Erde und Pferdehaar-Ködern — führten zur Bildung von fertilen Kleisthezien. Kreuzung von Monoascosporen-Kulturen zeigten, daß dieser Keim heterothallisch ist. Die Form des Ascocarps ist typisch für die Gattung Arthroderma. Das perfekte Stadium wurde als “Arthroderma benhamiae” sp.nov. bezeichnet.

The differentiation ofTrichophyton ment agrophitesfromT. rubrumby a simple urease test

Seventy isolates of Trichophyton mentagrophytes, 104 isolates of T. rubrum, and 8 isolates of T. mentagrophytes var. erinacei were tested on a modified Christensen's medium for their ability to split urea. 92·8% of the isolates of T. mentagrophytes were positive within 7 days but no isolates of T. rubrum and T. mentagrophytes var. erinacei. A comparison of the urease and hair perforation tests was made. The urease test offers a rapid and reliable method of separating these two species.

In vitro hair cultures for differentiating between atypical isolates of Trichophyton mentagrophytes and Trichophyton rubrum.

Isolates ofT. mentagrophytes andT. rubrum are encountered that cannot be distinguished from each other solely on the basis of morphological criteria.