Morphological changes of trichophyton mentagrophytes under the influence of increased carbon dioxide tension

Summary Growth pigment production as well as macroconidia and arthrospore formation ofTrichophyton mentagrophytes are stimulated under the influence of increased carbon dioxide tension. Macroconidia with spirals and pistol forms of macroconidia are observed.The granular form ofT. mentagrophytes displays an asteroid growth (Dextrose agar of Sabouraud) with an ingrowth and elongation of the ray branches in the agar and a decrease of the air-mycelium. The culture completely resembles to those ofT. mentagrophytes varasteroides. The macroconidia appear elongated and they acquire an asteroid arrangement. The less granular strains ofT. mentagrophytes take the appearance ofT. interdigitale type.An analogy is made between these morphogenetic changes under the effect of increased CO₂ tension in vitro and the influence of the animal organism in the evolution of the growth forms of dermatophytes in vivo in the process of their parasitic adaptation.     

In vitro hair cultures for differentiating between atypical isolates ofTrichophyton mentagrophytes andTrichophyton rubrum

Summary Isolates ofT. mentagrophytes andT. rubrum are encountered that cannot be distinguished from each other solely on the basis of morphological criteria.Since these two species fundamentally differ in the manner in which they attack hairin vitro, this property can be used as a diagnostic aid, when correlated with their morphologic characteristics as developed on a variety of media. T. mentagrophytes radially penetrates hair segments immersed in water forming wedge-shaped perforations.T. rubrum does not perforate hair.The method of determining the ability or inability ofT. mentagrophytes orT. rubrum to perforate hair and the use of this test in identifying those species are described.     

Molecular cloning ofTrichophyton mentagrophytes DNA sequences with promoter activity inEscherichia coli

A promoter probe library from the dermatophyte fungusTrichophyton mentagrophytes has been constructed in the pVB32 plasmid vector. Using this library, a set ofT. mentagrophytes DNA sequences with promoter activity inEscherichia coli has been cloned. The size and the resistance phenotype conferred by these DNA fragments varied. Southern blot analysis confirmed that they were derived fromT. mentagrophytes genomic DNA.     

Morphological response of Trichophyton mentagrophytes to keratin

Summary The protein keratin can induce a reversible change in morphology of some granular strains ofTrichophyton mentagrophytes leading to a gross appearance which is indistinguishable from the pleomorphic mutation. The only other chemical which induced the same morphological change was a low concentration of sodium acetate. Pleomorphic cultures ofT. mentagrophytes were unaffected.     

Enzymes of Trichophyton rubrum

Jensen, Altschuler &Bard (1957) have surveyed the respiratory enzymes ofTrichophyton mentagrophytes. Enzymes of the hexosediphosphate, hexosemonophosphate, and tricarboxylic acid pathways were found plus a group of miscellaneous enzymes. In view of the close morphological, immunological, and nutritional similarities ofT. mentagrophytes toTrichophyton rubrum, we felt that a study of the enzymology of the latter organism had potential value in forming a basis for the comparison of the two dermatophytes. Our results showed that cell-free extracts ofT. rubrum contain glucokinase, TPN-dependent glucose and fructose dehydrogenases and separate TPN- and DPN-linked glycerol dehydrogenases. These results are in accord with findings of other investigators. ATPase activity was minimal, and shikimic acid kinase, and shikimic and quinic acid dehydrohydrogenases were not detected.     

Urease activity inTrichophyton mentagrophytes

Urease activity was detected in the dermatophyteTrichophyton mentagrophytes cells at early exponential phase of growth. Specific activity of urease decreased with culture age. At exogenous urea concentrations above 2 mm formation of urease was inhibited. The pH optimum lay at 7–7.5, the K_m being 14 mm. No urease activity could be detected in cell-free culture fluid ofT. mentagrophytes. No endoor exocellular urease activity could be detected in aT. rubrum strain grown with or without urea.     

Differentiation of trichophyton rubrum from trichophyton mentagrophytes

Conclusions Of the several morphological and physiological criteria that have been proposed to identifyTrichophyton rubrum andTrichophyton mentagrophytes differentially, only the hair invasion test agrees with the immunological results reported here.A typical strain ofT. rubrum andT. mentagrophytes was obtained from the Centraalbureau voor Schimmelcultures (Netherlands) and was used as reference strain. All isolates that did not invade hair shafts (in vitro) and that produced three precipitate lines in agargel diffusion tests against anti-T. rubrum serum (refence strain, Tr-1) were placed in one group. These isolates all also produced a red undersurface pigment and macroconidia with long parallel sides. They were labledT. rubrum.Other isolates that did invade hair shafts, and produced only two precipitate lines against anti-T. rubrum serum were placed in another group and were labeledT. mentagrophytes. These isolates had variable characteristics of pigment production, colony and conidial morphology.The antigenic studies thus corroborate the validity of the hair invasion test. The hair invasion test will probably remain in wider use because of its simplicity.     

Repeated Ubiquitin Genes in Trichophyton mentagrophytes

Using Trichophyton mentagrophytes cDNA as a template, we performed PCR amplification with the UB1S and UB1R primers for isolation of a partial fragment of T. mentagrophytes ubiquitin gene. We screened the T. mentagrophytes cDNA library prepared with Uni-ZAP phage vector by hybridization with the T. mentagrophytes ubiquitin fragment, UB1S-UB1R. The nucleotide and deduced amino acid sequences of T. mentagrophytes ubiquitin gene encoded two ubiquitin repeats in 162 bp to 624 bp. The deduced amino acid sequences of ubiquitin from T. mentagrophytes shared about 98% similarity with those of Saccharomyces cerevisiae, Neurospora crassa, and Cryptococcus neoformans. Received: 28 April 1999 / Accepted: 22 June 1999     

Detection of antigens in mycelial and in arthroconidial phases ofTrichophyton mentagrophytes

Protein pattern changes were investigated in the filamentous fungusTrichophyton mentagrophytes during the morphological transition induced by increased temperature and higher CO₂ partial pressure in cultivation atmosphere. The differences between the mycelial and the arthroconidial phase were characterized by SDS-PAGE and by immunodetection with mouse polyclonal antibodies. The components found by Western blotting in mycelia were 88, 86, 32, 29, 19.5, 18.5 kDa, in arthroconidia 108, 92, 88, 66, 56, 41, 39, 19.5 kDa. The results suggest the participation of some heat shock associated proteins ofT. mentagrophytes in host immune response against mycotic infection.     

Characterization of siderophores produced by different species of the dermatophytic fungiMicrosporum andTrichophyton

The dermatophytic fungiTrichophyton spp andMicrosporum spp secrete ferrichrome type siderophores under low iron conditions. Three different species ofMicrosporum, i.e.M. qypseum, M. canis andM. audouinii, as well asT. rubrum produce ferrichrome C and ferricrocin, whereasT. mentagrophytes andT. tonsurans produce only ferrichrome. The identification of the siderophores was established by means of thin layer chromatography, high performance liquid chromatography and mass spectroscopy.     

A short review on dermatophytoses of animals in Romania

Dermatophytoses of animals in Romania are reviewed. Ringworm infections have been found in cattle (whereT. verrucosum was the only isolated agent), horses (the causative organisms beingT. verrucosum, T. mentagrophytes andM. equinum), cats (dermatophytes isolated:M. canis andT. quinckeanum), dogs (M. canis andM. gypseum), fowlsT. gallinae). From the laboratory animals: guinea pigs (T. mentagrophytes, M. audouinii, T. rubrum), mice (T. quickeanum andT. mentagrophytes), rats (T. mentagrophytes), rabbits (T. mentagrophytes andM. canis) and hamster)T. mentagrophytes). Among the wild animals, only the chamois had a ringworm infection byM. gypseum, other large or smaller wild animals harboring only saprophytically some poozhilic and geophilic dermatophytes.     

SDS-PAGE separation of dermatophyte antigens,and western immunoblotting in feline dermatophytosis

Water-soluble antigens liberated from the disrupted mycelium of nine dermatophytes (seven isolates ofMicrosporum canis, one each ofMicrosporum gypseum andTrichophyton mentagrophytes) were compared by analytical slab SDS-PAGE. No substantial differences were observed between the protein bands of theM. Canis isolates, but certain distinctive bands were apparent in the other two species examined. Western immunoblotting usingM. canis-derived antigens separated by SDS-PAGE was used to investigate the humoral immune response in 79 cats with naturally-occurring dermatophytosis (72 withM. canis, six withM. gypseum and one withT. mentagrophytes) and this information was compared to results of immunoblots from 46 control (non-dermatophyte exposed) cats. Seven dominant bands (bands which occurred frequently and stained heavily) were identified in immunoblots from the dermatophyte-infected cats with apparent molecular weights varying between 39 and 120 kD. None of these bands were totally specific markers for dermatophytosis as a variable proportion of the control cats showed reactivity to all these proteins. However, most (73%) of the dermatophyte-infected cats showed reactivity to six or seven of the identified bands whereas most (80%) of the control cats showed reactivity to between zero and three of these bands (p<0.005). Western immunoblotting could be used to select individual immunodominant antigens for further evaluation of protective (cell-mediated) immunity.     

Mating patterns of dermatophytes of diverse origin in India

The mating patterns of Trichophyton mentagrophytes var. interdigitale (74 isolates) and the Microsporum gypseum complex (17 isolates) of diverse origin and T. rubrum (25 isolates) and T. tonsurans (10 isolates) of clinical origin were studied. The results of the study showed that the teleomorph of the Indian isolates of T. mentagrophytes belong to Arthroderma vanbreuseghemii, undetermined teleomorphs of T. mentagrophytes var. interdigitale (+) mating types, and undetermined teleomorphs of T. mentagrophytes var. interdigitale indeterminate mating types. All the isolates of T. rubrum and T. tonsurans were found to be of the (-) mating type.     

Lipolytic activity of dermatophytes

Lipolytic activity of dermatophytes was tested by the method generally used forCandida lipolytica. Most of the freshly isolated strains ofMicrosporum canis, M. gypseum, Epidermophyton floccosum andTrichophyton mentagrophytes gave positive reactions, whereas, only few strains ofT. schoenleini, T. violaceum, T. megnini, T. rubrum andT. tonsurans yielded such reactions. Among subcultured strains, it was found a decreased lipolytic activity inMicrosporum species and an increased lipolytic activity inEpidermophyton and someTrichophyton species.Part of this work was performed at Serviço de Doenças Infecto-Contagiosas (Secção de Dermatologia), Hospital de Curry Cabral - Lisboa.     

Etude sur la contamination par les champignons dermatophytes d'une population de petits mammiferes sauvages en Alsace

Résumé Des 3782 petits mammifères sauvages capturés au cours d'une enquête poursuivie pendant plus de 4 ans, 15,78% sont contaminés par des dermatophytes.Les espèces de dermatophytes ou champignons, apparentés qui sont rencontrées ne sont que 6;Microsporum persicolor etTrichophyton mentagrophytes sont les espèces dominantes. Les campagnols roussâtres sont, de façon significative, plus contaminés parM. persicolor (11,63%) que parT. mentagrophytes (4,36%). Au contraire, les mulots sont plus contaminés parT. mentagrophytes: 13,95% contre 3,50% contaminés parM. persicolor. Les campagnols roussâtres mâles (13,33%) sont plus contaminés que les femelles (9,45%) parM. persicolor et les mulots mâles (17,09%) plus contaminés que les femelles (9,95%) parT. mentagrophytes. La présence deM. persicolor est notée pour la première fois chez le grand hamster. L'étude histologique de certains animaux permet de remarquer l'existence de lésions dermatophytiques. A l'isolement deT. mentagrophytes correspond une attaque pilaire de type endo-ectothrix; à l'isolement deM. persicolor correspond une attaque limitée à l'épiderme.

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3782 small wild mammals trapped during a 4 year survey have been examined in relation to a possible contamination by dermatophytes. 15.78% of the animals were contaminated.The prevailing species wereMicrosporum persicolor andTrichophyton mentagrophytes. The bank voles were significantly more contaminated byM. persicolor (11.63%) than byT. mentagrophytes (4.36%). On the contrary the wood mice were more contaminated byT. mentagrophytes: 13.95% as against 3.50% contaminated byM. persicolor. The male bank voles (13.33%) were more contaminated than the females (9.45%) byM. persicolor and the male wood mice (17.09%) more contaminated than the females (9.95%) byT. mentagrophytes. The occurrence ofM. persicolor in common hamster is noted for the first time. The existence of a pathological lesion in relation to the fungal contamination was noted in the small group of rodents examined histologically: WhenT. mentagrophytes was isolated the hairs were invaded in the endo-ectothrix type pattern; whenM. persicolor was cultivated, hairs are not attacked but only the epidermis.

     

Hybridization and sexual stimulation inTrichophyton mentagrophytes

Mating and sexual stimulation tests applied to 132 strains of this dermatophyte isolated in Czechoslovakia revealed among them strains ofArthroderma benhamiae (40 strains of the+mating type, one of the—mating type) andA. vanbreuseghemii (three strains of the+type, seven of the-type). No dependence was found concerning the anamorphic variety (T. mentagrophytes var.granulosum, var.interdigitale, var.mentagrophytes, var.quinckeanum), teleomorphic species, mating type and the clinical localization of dermatophytosis. Plausible reasons of different frequencies of the mating types are discussed.     

Equine ringworm due to Trichophyton mentagrophytes var. quinckeanum

Summary T. mentagrophytes var.quinckeanum was isolated from a case of equine tinea and this finding is thought to be unique. Although it is considered that the fungus is closely related toT. mentagrophytes, the small differences in the relative pathogenicity for animals and man, the unusual clinical pattern which can be seen, and the downy nature of primary isolates on Sabouraud's medium are features not to be expected withT. mentagrophytes infections. The ability of this fungus to produce green fluorescence in the hairs of infected guinea pigs is felt to be its most unique feature and warrants its separate identity asT. mentagrophytes var.quinckeanum.     

Variability of biochemical characteristics in strains of Trichophyton mentagrophytes

The characteristics of 23 strains of Trichophyton mentagrophytes isolated from clinical samples, were studied. Sabouraud agar was the most adequate medium to inhance at their utmost the different taxonomical features. Variability of enzymatic reactions in strains of T. mentagrophytes was observed.     

Etudes comparées des Dermatophytes isolés de grottes et d'étables en Bulgarie

Résumé De 28 prélèvements du sol de fermes et d'étables, 18 sont positifs pour les formes imparfaites des dermatophytes primitifs suivants:M. gypseum 15,M. ajelloi 7 etM. cookei 2. Une flore associative abondante comprend des moisissures et desAleurisma (Chrysosporiums) diverses.T. mentagrophytes n'est pas découvert dans ces échantillons de sols.De 51 prélèvements, effectués de diverses profondeurs du sol sabloneux d'une grotte peu visitée, 39 sont positifs essentiellement pour la forme à cleistothèces steriles deT. terrestre. La flore associative de moisissures et desChrysosporiums est pauvre.La prédominance du stage parfait anascosporé deT. terrestre dans le sol pauvre, sabloneux et la fréquence relative du stage imparfait, macroconidial deM. gypseum dans le sol riche en matières organiques et kératine, sont attribuées au différent degré d'adaptation parasitaire de ces deux dermatophytes.Phylogénetiquement,T. mentagrophytes présente plutôt une espèce zooanthropophile, hétéroreceptive, qu'une espèce tellurique.En règle générale, le reservoir de l'infection des dermatophytes, leur habitat, est en relation avec le grade de la différenciation biologique de chaque espèce.

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Summary In 18 of 28 soil samples, collected from stables, the imperfect stage of primitive dermatophytes was isolated:M. gypseum 15,K. ajelloi 7 andM. cookei 2. An abundant flora of different fungi, includingChrysosporium species has been found to be added to the dermatophytes mentioned above.T. mentagrophytes could not to be discovered in the soil samples.From 51 samples, collected from the different depths of a not very frequented cave with sandy soil, 39 proved to be positive for abortive-cleistothecial form ofT. terrestre. The additional flora of fungi was a poor one.The predominence of perfect anascigerous stage ofT. terrestre in a meager and sandy soil and the relative frequency of imperfect, macroconidial stage ofM. gypseum in a soil, rich in organic compounds and keratin, has been attributed to the different degrees of adaptation of these two dermatophytes.Phylogenetically,T. mentagrophytes represents rather a zooanthropophylic, heteroreceptive dermatophyte, than a soil one.In a general way, the main reservoir of the dermatophytes (its habitat), is connected with the stage of biological differenciation of every single species.

     

The occurrence of keratinophilic fungi in texas soil

Summary A total of 137 soils, 27 coming from caves and 110 from outdoor lands of Texas, were examined for the presence of keratinophilic fungi by the use of the ToKaVa hairbaiting technique. Twenty three and 69 fungal isolates, respectively, were recovered from these areas. Microsporon gypseum was the most common isolate, followed byTrichophyton mentagrophytes, andT. terrestre. M. gypseum was recovered from caves in a very high frequency (67 %), in comparison to its presence in the outdoor soils (10 %).Fifteen strains ofChrysosporium, belonging to four species, were isolated. Fourteen of these isolates were recovered from shady areas under trees. None of these had been isolated from Texas soil before.