Extensive dermatophytoses caused by Trichophyton mentagrophytes and Microsporum canis in a patient with AIDS

Retrospective studies have shown the occurrence of episodes of deep or superficial fungal infections in 58 to 81% of HIV/AIDS patients as a result of impairment of cell immunity. We describe a case of disseminated cutaneous dermatophytoses caused by Trichophyton mentagrophytes and Microsporum canis in a patients with AIDS. Diagnostic and therapeutic problems in relation to this unsual presentation are emphasized as well as the importance of an early mycologic diagnosis to prescribe antifungal therapy.     

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.     

Basic carriers of Trichophyton mentagrophytes var. gypseum in the Sverdlovsk region

Tests for myococarriers were made on 4.297 wild small mammals. Clinical examinations only were carried out on 1,204 animals, both clinical and laboratory examinations on 3,093 animals. The suppurative form of trichophytosis was diagnosed in only one specimen of Microtus oeconomus out of 1,204 animals examined. T. ectothrix microides was found in the hair taken from the focus. T. mentagrophytes var. gypseum was obtained by culture on nutrient media. No clinical signs of mycosis were found in 3,093 animals, but seeding of the hair 175 animals (5.65%) on Sabouraud's agar with chlortetracycline and acti-dione produced cultures of T. mentagrophytes var. gypseum. The fungus was most frequently isolated in clinically healthy water rats, common field voles and field mice (Arvicola terrestris, Microtus arvalis, Apodemus agrarius). Mycocarriers were most frequently found among small mammals living in corn fields (5.9%), less frequently in water meadows (0.9) and sporadically in forests and bushes (0.1%). The possibility of bringing mycocarriers from the fields into inhabited areas during the transport of forage was reported.     

Saprophytic occurrence of Trichophyton mentagrophytes and Microsporum gypseum in the coats of healthy laboratory animals

A group of 199 healthy laboratory animals, comprising 63 guinea pigs; 58 white mice. 47 rats and 31 rabbits, was sampled for the presence of pathogenic dermatophytes. T. mentagrophytes, var. granulare, was isolated in 10% (5-guinea pigs, 6 mice, 6 rats and 2 rabbits) and M. gypseum was found in 7 animals (3 guinea pigs, 3 mice and one rat). No ringworm lesions were observed in the respective animals. This is the first report on such findings in Israel.     

In vitro characterization of Trichophyton rubrum and T. mentagrophytes biofilms

Dermatophytes are fungi responsible for a disease known as dermatophytosis. Biofilms are sessile microbial communities surrounded by extracellular polymeric substances (EPS) with increased resistance to antimicrobial agents and host defenses. This paper describes, for the first time, the characteristics of Trichophyton rubrum and T. mentagrophytes biofilms. Biofilm formation was analyzed by light microscopy, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) as well as by staining with crystal violet and safranin. Metabolic activity was determined using the XTT reduction assay. Both species were able to form mature biofilms in 72?h. T. rubrum biofilm produced more biomass and EPS and was denser than T. mentagrophytes biofilm. The SEM results demonstrated a coordinated network of hyphae in all directions, embedded within EPS in some areas. Research and characterization of biofilms formed by dermatophytes may contribute to the search of new drugs for the treatment of these mycoses and might inform future revisions with respect to the dose and duration of treatment of currently available antifungals.     

Enzymatic activities of Microsporum canis and Microsporum gypseum strains.

The presence of 11 enzymatic activities, detected by qualitative methods, and 19 enzymes, semi-quantitatively detected by API ZYM system, in strains belonging to Microsporum canis and Microsporum gypseum has been studied. No pronounced differences were noted between Microsporum canis and Microsporum gypseum, although Microsporum gypseum presented in some cases more intense enzymatic activities than Microsporum canis.     

Microsporum canis infection in calves.

Microsporum canis infection, seldom reported in calves, is described. The organism was isolated from skin scrapings collected from ringworm lesions mainly on the heads of 2 naturally infected calves. The organism was studied in vitro, and experimentally on guinea-pigs.     

Partial purification and some biochemical charactcristics of exocellular keratinase from Trichophyton mentagrophytes var. erinacei

The dermatophyte Trichophyton mentagrophytes var. erinacei isolated from patients infected with tinea cruris was cultured in Sabouraud dextrose broth, from which an exocellular kenitinase extract was obtained. The keratinase was partially purified with sephadix G-100 gel filtration. Some biochemical characteristics of the purified enzyme were examined. Its molecular weight was estimated to be 38000 dalton on sodium dodecyle sulfate polyacrylmide gel electrophoresis (SDS-PAGE). The optimal pH was 5.5 and optimal temperature for the highest keratinase activity was 50°C. The enzyme activity was specifically increased against guinea pig hair and fibrous protein and inhibited by phenylmethylsulfonylfloride. This revised version was published online in June 2006 with corrections to the Cover Date.     

Die Hauptfruchtform des Trichophyton mentagrophytes var. granulosum,Arthroderma oláhii Spec. Nov.

Ohne Zusammenfassung     

Antigenic characterization of Microsporum canis,M. distortum,M. equinum,M. ferrugineum and Trichophyton soudanense cultures

The authors investigated the antigenic properties of a group of closely related dermatophytes whose components may be morphologically confused with one another: Microsporum canis, M. distortum, M. equinum, M. ferrugineum and Trichophyton soudanense. By using reference antigens and adsorbed monospecific antisera, it was possible to serologically distinguish the reference strains by the exoantigen technique. Their common and specific antigenic determinants were visualized by cross-immunoelectrophoresis tests with intermediate gel.     

Carotenogenesis associated with arthrosporulation of Trichophyton mentagrophytes.

Carotenoid pigments were demonstrated in arthrospores of the dermatophyte Trichophyton mentagrophytes but were absent from hyphae and microconidia of this fungus. Incubation at higher temperatures (39 degrees C) allowed arthrosporulation to occur, but essentially no carotenoid was detected in such arthrospores. The carotenoid formation in arthrosporulating T. mentagrophytes did not appear to be either induced or stimulated by light illumination. Mature arthrospores contained the carotenoids phytoene, phytofluene, zeta-carotene, neurosporene, lycopene, and gamma-carotene and a few minor unidentified carotenoids. These carotenoids were localized within intracellular granules consisting of osmiophilic matrices and complex membranous elements. This is the first demonstration of carotenoid pigments in dermatophytic fungi.     

Effects of deferoxamine methanesulfonate on Trichophyton mentagrophytes.

Deferoxamine methanesulfonate (Desferal), an iron chelator, inhibited germ tube formation and growth of Trichophyton mentagrophytes in a microculture assay. A 50% reduction of germ tube formation required Desferal at 5 mg/ml and a 50% reduction of growth required 1.5 mg/ml. Growth was almost completely inhibited with 50 and 100 mg/ml. Also, Desferal at 100 mg/ml inhibited further elongation when added to short hyphae (II and 21 micrometer), but showed less inhibitory effects when added to long hyphae (64 micrometer). Iron (133 microgram/ml) reversed the inhibition of growth produced by incubating spores with Desferal at 5 mg/ml, providing iron was added before 72 h incubation. Desferal at 100 mg/ml decreased viability of activated spores incubated for 3 days at 30 degrees C, but did not decrease viability of spores incubated for 3 days at 4 degrees C. The growth inhibitory effect of Desferal and transferrin were compared. Transferrin was inhibitory at low molarities (0.001 to 1.0 mM), while Desferal was inhibitory only at higher molarities (greater than 1 mM). Desferal (0.05 mM) also reversed the inhibition expected with 0.05 mM transferrin. These findings indicate that Desferal and transferrin deprive T. mentagrophytes of nutritional iron and thus inhibit growth of the fungus. Low concentrations of Desferal can also promote growth in the presence of transferrin.