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PubMed1998

A survey of dermatophytes isolated from human patients in the United States from 1993 to 1995.

A survey of dermatophytes, isolated from human patients seeking medical attention, was conducted for the years 1993 to 1995. Data were collected from 23 states throughout the continental United States and the District of Columbia and from 44 to 45 laboratories. These data were compared with the results of two earlier surveys (1979 to 1981 and 1985 to 1987). In contrast to the earlier surveys Trichophyton tonsurans became the most frequently isolated dermatophyte (44.9%) followed by T. rubrum (41.3%), T mentagrophytes (8.5%), Microsporum canis (3.3%) and Epidermophyton floccosum (1.1%). Other dermatophytes were recovered from less than 1%. The increase in T. tonsurans from 27.9% in the 1979 to 1981 survey, to 41.3% in the current survey, accompanied by the decline of T. rubrum from 53.7% to 41.3% is statistically significant (P < .001)

Arthrodermataceae↗

PubMed2005

[In vitro antifungal activity of voriconazole against dermatophytes and superficial isolates of Scopulariopsis brevicaulis].

We have studied the in vitro antifungal activity of voriconazole, fluconazole and itraconazole against 252 clinical isolates of dermatophytes and Scopulariopsis brevicaulis by a standardized agar diffusion method (NeoSensitabs). Several important factors such as temperature (28 degrees C vs. 35 degrees C) and incubation time (2-10 days vs. 18-74 h) were adapted to dermatophytes and Scopulariopsis requirements. Voriconazole showed an excellent activity against most species of dermatophytes, higher than itraconazole and fluconazole. However, S. brevicaulis isolates were highly resistant to all azoles used in this study. Voriconazole might be an interesting antifungal alternative to refractory superficial mycoses.

Antifungal Agents↗

PubMed1978

Geographical distribution of the dermatophytes: a review.

In these days of rapid transit from continent to continent, and the increasing mobility of people, agents of disease are no longer geographically restricted. Disease contracted half way across the world may become manifest in a country in which the pathogen is not normally found. Thus knowledge of the geographical distribution of pathogens becomes increasingly important when a diagnosis is being made. This is as true of ringworm fungi as of any other group of microorganisms. In the last 12 years, in the Mycological Reference Laboratory, an increasing number of exotic dermatophytes have been seen, related in part at least to the great increase in the number of non-British residents. Not all species of dermatophytes are cosmopolitan in their distribution throughout the world. While some have been recorded from every continent, others have geographically limited areas of greater or lesser extent. Surveys taken at intervals in a country may show a rise and fall in occurrence of several species as habits change, populations move and medical facilities became increasingly well-distributed. There have been few geographical surveys of ringworm fungi that have covered the world. Ajello (1960, 1974) has reviewed the individual species with regard to geographical location, while Vanbreuseghem & de Vroey (1970) attempted to estimate the relative importance of the various species in terms of numbers of isolations reported. This paper therefore reviews the world dermatophyte flora in terms of the dominant agents in the various countries, and some of the changes that have been recorded.

Africa↗

PubMed1999

In vitro evaluation of antifungal properties of phenylpropanoids and related compounds acting against dermatophytes.

Thirty-four arylpropanoids and related compounds were evaluated in vitro for antifungal properties. Among them, 22 phenyl-, 4 naphthyl-, and 4 phenanthrylpropanoids; naphthalene; phenanthrene; and 2-chloro-1-hexyl-1-propanone were tested against dermatophytes by the agar dilution method. alpha-Halopropiophenones exhibited a broad spectrum of activities against Microsporum canis, Microsporum gypseum, Trichophyton mentagrophytes, Trichophyton rubrum, and Epidermophyton floccosum, with MIC values between 0.5 and >50 microg/mL. Keto, alcohol, and alpha-haloketo propyl derivatives of naphthalene and phenanthrene also showed very good activity against all dermatophytes tested, clearly showing that in these series, a halogen atom is not necessary for activity. Phenanthryl derivatives were more active (MICs, 3-20 microg/mL) than naphthyl ones (MICs, 3-50 microg/mL). A structure-activity relationship study was carried out and aided in establishing the structural requirements of arylpropanoids for antifungal activities. Because dermatophytes are a group of fungi that characteristically infect the keratinized areas of the body, these new series of antifungal compounds open the possibility of discovering new topical antifungal drugs for the treatment of dermatomycoses, which are frequently very difficult to eradicate.

Antifungal Agents↗

PubMed2002

Dermatophytes isolated from symptomatic dogs and cats in Tuscany, Italy during a 15-year-period.

Between January, 1, 1986 and December, 31, 2000, dermatological specimens from 10.678 animals (7.650 cats and 3.028 dogs) were examined for dermatophytes. All the animals presented clinical signs of ringworm. Two thousand-four hundred fifty-six of the 10.678 (23%) examined animals scored positive for dermatophytes, 566 out of 3.028 canine (18.7%) and 1890 out of 7.650 feline specimens (24.7%). Microsporum canis constituted 83% and 97% of the isolated dermatophytes respectively in dogs and cats, M. gypseum represented 13% and 2.6% and T. mentagrophytes 5.5% and 0.2%. A sexual predisposition for mycotic infections was not observed. The animals with less than 1 year of age were more frequently infected. Canine toy breeds showed a significantly higher (P < 0.001) prevalence of infections by M. canis. Microsporum gypseum was mostly recorded from sporting (hunting) breeds [such as T. mentagrophytes (6.7%)]. Microsporum canis was isolated from long-haired cats with a ratio of 2:1 versus short-haired cats, while M. gypseum and T. mentagrophytes were never recovered from Persian cats. The annual distribution of the infections in dogs showed a significantly higher incidence for M. gypseum in summer versus winter and spring, while the recovery rate of M. canis from cats was very significantly higher in fall and winter than in summer and spring. Trichophyton mentagrophytes did not show a similar seasonal distribution.

Animals↗

PubMed2003

Fluorescent method for studying the morphogenesis and viability of dermatophyte cells.

The dermatophyte Microsporum canis is commonly isolated from human and animal infection. The morphogenesis of this fungus was studied during its developmental stages through the fluorescent method Fluorescein Diacetate and Ethidium Bromide. To this end, 50 microl dermatophyte suspension were transferred onto cellophane wrapping esterilized discs (2.5 cm of diameter) placed over the surface of Sabouraud dextrose agar on Petri dishes and incubated at 25 degrees C for 30 days. Every 60 minutes during the first 24 hours and every 12 hours for next 29 days, one disc was transferred onto glass slide, covered with equal volumes of freshly prepared fluorescein diacetate (FDA) and ethidium bromide (EB) solution, mounted with a coverslip and incubated in the dark for 30 minutes, at 25 degrees C. Each preparation was then examined on a fluorescent microscope. M. canis presented well defined growth stages: (1) tumescence of cells; (2) germination; (3) development of hyphae; (4) production of conidia and (5) tumescence and formation of arthroconidiae. Using the fluorescent method, non viable cells showed a light bright red coloration and viable cells presented green fluorescence. The principal morphological changes have occurred between the 3rd until the 18th day of culture. The method is very useful to demonstrate the dermatophyte growth stages as well as the perfect differentiation between viable and non viable cells.

Ethidium↗

PubMed1999

Antifungal activity of plant extracts against dermatophytes.

The aqueous extracts (15 micrograms ml-1 medium) of 22 plants used in folkloric medicine in Palestine were investigated for their antifungal activity and minimum inhibitory concentrations (MICs) against nine isolates of Microsporum canis, Trichophyton mentagrophytes and Trichophyton violaceum. The extract of the different plant species reduced colony growth of the three dermatophytes by 36 to 100% compared with the control treatment. Antimycotic activity of the extract against the three dermatophytes varied significantly (P < 0.05) between test plants. Extracts of Capparis spinosa and Juglans regia completely prevented growth of M. canis and T. violaceum. The most active extracts (90-100% inhibition) were those of Anagallis arvensis, C. spinosa, J. regia, Pistacia lentiscus and Ruta chalapensis against M. canis; Inula viscosa, J. regia and P. lentiscus against T. mentagrophytes; and Asphodelus luteus, A. arvensis, C. spinosa, Clematis cirrhosa, I. viscosa, J. regia, P. lentiscus, Plumbago europea, Ruscus aculeatus, Retema raetam and Salvia fruticosa against T. violaceum. The MICs of these most active plants ranged from 0.6 to 40 micrograms ml-1. The three dermatophytes differed significantly with regard to their susceptibility to plant extracts. Trichophyton violaceum was the most susceptible being completely inhibited by 50% of the extracts followed by M. canis and T. mentagrophytes which were completely inhibited by only 23 and 14% of the extracts, respectively.

Antifungal Agents↗

PubMed2002

Did earthworms contribute to the parasitic evolution of dermatophytes?

The survival of dermatophyte species in the gut of four species of earthworms was studied by feeding the fungi to the earthworms. Recovery of the dermatophyte species in culture from the guts was only possible for Microsporum gypseum and Chrysosporium keratinophilum. In the light of these findings, we presume that earthworms could have influenced the parasitic evolution of certain dermatophytes.

Animals↗

PubMed2003

Species identification and strain differentiation of dermatophyte fungi using polymerase chain reaction amplification and restriction enzyme analysis.

BACKGROUND: Standard biochemical tests, microscopy, colony characteristics, and mating tests have conventionally been used for the identification of dermatophytes species, but these methods of identification are costly, time-consuming, and require special skills. OBJECTIVE: Our purpose was to identify a method that enables rapid species identification and strain differentiation of dermatophyte fungi. METHODS: We chose 4 restriction enzymes (BsYiI, DdeI, HinfI, and MvaI) that could produce different fragment patterns after enzyme digestion according to species or strain. We performed enzyme digestions after polymerase chain reaction amplification of internal transcribed spacer region and identified different restriction fragment length polymorphisms (RFLP) according to species and strains. RESULTS: All the species included in this study could be easily differentiated using any combination of 2 different restriction enzymes except Trichophyton rubrum and T raubitschekii, which produced identical digestion patterns after all 4 restriction enzyme digestions. In the case of T mentagrophytes, MvaI and DdeI each produced 2 distinct RFLP patterns. CONCLUSION: This study showed that internal transcribed spacer region analysis using polymerase chain reaction-RFLP through DdeI and MvaI is useful for rapid identification of the majority of dermatophytes species. However, there were 2 different band patterns by DdeI and MvaI restriction enzyme digestion and no correlations between morphologic types and RFLP patterns in T mentagrophytes.

Arthrodermataceae↗

PubMed1999

Dermatophyte infections in Melbourne: trends from 1961/64 to 1995/96.

A comparison of dermatophyte infections, diagnosed by specimens sent to the laboratory, between 1961/64 and 1995/96 revealed two major trends, namely the site of clinical disease and the types of dermatophytes causing tinea infections. There was a marked decrease in scalp specimens submitted. Pedal disease and nail infections remained the predominant entities. There was a marked increase in Trichophyton rubrum isolations, such that T. rubrum now accounts for 69.5% of all dermatophyte infections. Possible causes for these trends include altered hygiene standards, changing immigration patterns and the availability, restrictions and diagnostic requirements for the prescription of various antifungal drugs over this time period.

Adolescent↗

PubMed1984

DNA homology studies in the taxonomy of dermatophytes.

The taxonomy of the dermatophyte genera Trichophyton, Microsporum and Epidermophyton was investigated by determinations of DNA homology. DNA extracted from 10 isolates (seven species) of dermatophytes was reannealed by hydroxyapatite chromatography. DNA homology levels of 65-80% corresponded to species within a single genus. There was a general agreement with established classification, particularly in assigning species to separate genera. DNA from the Trichophyton state of Arthroderma benhamiae (NCPF 456) showed 71 and 76% homology with DNA from T. mentagrophytes (NCPF 224) and T. rubrum (NCPF 5034) respectively. T. terrestre showed low homology (25%) when compared with the other species of dermatophytes tested.

Arthrodermataceae↗

PubMed1994

Phylogeny of dermatophytes and dimorphic fungi based on large subunit ribosomal RNA sequence comparisons.

The phylogeny of dermatophytes and dimorphic fungi was considered using the large-subunit of ribosomal RNA (25S rRNA). Aligned sequences of 595 nucleotides covering the two most divergent domains D1 and D2, permitted a comparison of phylogenetic relationships at different levels. The dimorphic species (Onygenaceae) were significantly separated from dermatophytes (Arthrodermataceae) and from a third group including geophilic or very weakly pathogenic species (Onygenaceae and Gymnoascaceae). On a species level, the varietal status of Histoplasma duboisii and Histoplasma farciminosum, as close relations of Histoplasma capsulatum, was confirmed. The dimorphic fungus Emmonsia parva, in spite of a completely different parasitic form (adiaspores instead of yeast-like cells), clustered with Blastomyces dermatitidis which has a perfect form resembling that of H. capsulatum. From our data, teleomorphs of E. parva, Paracoccidioides brasiliensis and H. farciminosum, three dimorphic fungi known only under their anamorphic states, should belong to the family of Onygenaceae and the genus Ajellomyces. Among Arthrodermataceae, and family containing the most keratinophilic species, it was not possible to establish a clear hierarchy of species. Only Ctenomyces serratus, the species adapted to degrade keratin of feathers, Trichophyton ajelloi and Trichophyton terrestre were significantly separated. The speciation of true dermatophytes resulted most likely from a very recent evolution by adaptation to parasitism. Among species used as outgroups, the two emerging pathogens Pseudallescheria boydii (Scedosporium apiospermum) and Scedosporium prolificans (Scedosporium inflatum) were shown to be closely related to each other.

Arthrodermataceae↗

PubMedDate not supplied

Evaluation of the susceptibility of dermatophytes to antifungal drugs: a new technique.

The evaluation of the minimal inhibitory concentration (MIC) for pathogenic fungi is still a technically difficult assay. Insufficient standardization of the technique is often the basis of problems which appear. Culture characteristic of dermatophytes do not favour techniques usually used in bacteriology (Steers agar dilution method). A study was undertaken to compare the Steers agar dilution method and a new culture method to evaluate the minimal inhibitory concentration of antifungal compounds on several species of dermatophytes. The new method involves dilution of the antifungal drug in solid medium in a Petri dish. Standardized agar cylinders are cut from the plates and filled with inocula of the same size cut from plates of dermatophyte cultures. Such inocula facilitate analysis of the fungus in its natural growth conditions in vitro without being submitted to a disruptive preparative technique. The MIC values were similar for the two methods of evaluation in spite of important differences between the inocula. The new technique is reliable, quick, and highly reproducible. It is more efficient than the Steers agar dilution method because it enables assays to be run on several strains simultaneously and avoids labour-intensive procedures for the preparation of the inocula.

Allylamine↗

PubMed2005

Comparison of disk diffusion method and broth microdilution method for antifungal susceptibility testing of dermatophytes.

The use of the agar diffusion Neo-Sensitabs method to determine antifungal susceptibility of 59 isolates of dermatophytes, namely Epidermophyton floccosum, Microsporum canis, M. gypseum, Trichophyton mentagrophytes, T. rubrum and T. tonsurans to Clotrimazole (CLZ), Itraconazole (ITZ) and Terbinafine (TBF) is described. Results obtained are compared to the minimum inhibitory concentrations (MIC) determined by an adaptation of the NCCLS-M38-A procedure. Using the diffusion method, all strains showed a broad zone of inhibition at the first available reading time (3 or 7 days). Using the broth microdilution method, the geometric mean MIC (microg/ml) with regard to all isolates was < or = 0.03 for TBF, < or = 0.069 for CLZ and < or = 0.919 for ITZ. In both methods, TBF was the most active antifungal agent against all isolates tested. The two methods evaluated were able to detect the resistance of the quality control strains of Aspergillus fumigatus to ITZ. Even though a reference method for testing dermatophytes still has not been developed, our data suggest that the Neo-Sensitabs diffusion method could provide a simple procedure for the antifungal susceptibility testing of dermatophytes in the routine clinical laboratory.

Antifungal Agents↗

PubMed2005

Dermatophytes growth curve and in vitro susceptibility test: a broth micro-titration method.

The introduction of systemic antifungal drugs which act upon different targets is the main issue of the in vivo antifungal resistance control. Different factors, such as growth curve phase, quality of the specimen, quantity of the inoculum, temperature, pH, culture medium composition, incubation duration and solvent, are believed important factors affecting minimum inhibitory concentration (MIC) value to most of the antifungal agents. We assayed an in vitro susceptibility test with 40 isolates of dermatophytes: Microsporum canis, Trichophyton rubrum, Trichophyton mentagrophytes and Epidermophyton floccosum against griseofulvin, fluconazole, itraconazole and terbinafine, using the guidelines of the M38-P document approved by the NCCLS. We determined the growth curves, to estimate the specific growth rate (mu max) and the generation time (G) of each dermatophyte, using dry weight and spectrophotometry methods. We demonstrate that, at 192 h, all fungi tested had a constant growth curve and we considered this as the optimal time for MIC determination. Terbinafine, griseofulvin and itraconazole possessed the highest antifungal activity against the four groups of dermatophytes studied. Fluconazole demonstrated no efficacy. Our MIC results differ from other authors and this difference is due to the timing of the MIC determination based on the growth curve of each fungi tested.

Antifungal Agents↗

PubMed2000

Molecular approaches to the study of dermatophytes.

Dermatophyte species are common keratinophilic fungi responsible for superficial infections called dermatophytosis or ringworm and composed of three anamorphic genera, Trichophyton, Microsporum and Epidermophyton. Through the use of several complementary molecular methods, dermatophytes have been shown to constitute an homogeneous group of species with very low genetic diversity contrasting with high phenotypic heterogeneity. For diagnostic applications, distinction among isolates to the species level was easily performed using polymerase chain reaction-based assays, which could be useful tools in the mycology laboratory, particularly for atypical isolates. In contrast, in all but a few cases distinction between dermatophyte strains has failed, which has hindered the development of molecular-based epidemiological investigations.

Animals↗

PubMed2006

In vitro activity of Citrus bergamia (bergamot) oil against clinical isolates of dermatophytes.

OBJECTIVES: Recently, bergamot oil was shown to be a potent antifungal agent in vitro against clinically important Candida species. In this study, the activities of bergamot natural essence and its furocoumarin-free and distilled extracts on dermatophytes such as Trichophyton, Microsporum and Epidermophyton species were investigated. METHODS: In vitro susceptibility testing assays on 92 clinical isolates of dermatophytes (Trichophyton mentagrophytes n = 20, Trichophyton rubrum n = 18, Trichophyton interdigitale n = 15, Trichophyton tonsurans n = 2, Microsporum canis n = 24, Microsporum gypseum n = 1 and Epidermophyton floccosum n = 12) were performed using the CLSI M38-A broth microdilution method, except for employing an inoculum of 1-3 x 10(3) cfu/mL. MICs were determined at a visual endpoint reading of 80% inhibition compared with the growth control. RESULTS: MICs (v/v) of all fungi ranged from 0.156% to 2.5% for the natural essence, from 0.02% to 2.5% for the distilled extract, and from 0.08% to 1.25% for the furocoumarin-free extract. The three isolates of T. tonsurans and M. gypseum exhibited the highest MIC values. CONCLUSIONS: Data from this study indicate that bergamot oil is active in vitro against several common species of dermatophytes, suggesting its potential use for topical treatment of dermatophytoses.

Antifungal Agents↗

PubMed1996

Dermatophytes contain a novel lipid-like leukocyte activator.

In the early phase of dermatophytosis, neutrophils are regularly detected microscopically in the infected skin. Although neutrophil recruitment may at least in part occur indirectly by complement activation, we asked whether dermatophytes might release chemoattractants for neutrophils. We cultivated various strains of different dermatophytes and tested fungal extracts for the presence of neutrophil chemotactic activity. As a result, we detected neutrophil chemotactic activity only in diethylether extracts, but not in aqueous extracts. We purified this lipid-like leukocyte activator (LILA) to apparent homogeneity by reversed-phase high performance liquid chromatography and found that purified LILA does not show ultraviolet absorption at wavelengths > 210 nm. Biologic studies revealed that LILA is as effective as formyl-methionyl-leucyl-phenylalanine in eliciting neutrophil chemotaxis, degranulation, and activation of the respiratory burst. Desensitization experiments in chemotaxis and degranulation with leukotriene B4, platelet-activating factor, or 5-oxo-eicosanoids revealed that LILA does not cross-desensitize with any of these other lipid-like attractants and thus possibly acts via a distinct as yet postulated neutrophil receptor. It is hypothesized that LILA, similarly to formylated methionyl peptides in bacteria, represents a dermatophyte- and possibly fungus-specific lipid compound that allows the host phagocytes to specifically recognize fungal infection. This system would be similar to the recognition of bacteria by phagocytes via N-formylated methionyl peptides, which represent a characteristic and unique system to identify bacteria.

Arthrodermataceae↗