The effect of isoflavaspidic acid PB extracted from Dryopteris fragrans (L.) Schott on planktonic and biofilm growth of dermatophytes and the possible mechanism of antibiofilm

ETHNOPHARMACOLOGICAL RELEVANCE

Dryopteris fragrans (L.) Schott (D. fragrans), a deciduous perennial herb, has been traditionally used for treatment of various skin diseases in Heilongjiang province of China for many years. Phloroglucinol derivatives extracted from D. fragrans were the most effective fraction against dermatophytes. Isoflavaspidic acid PB is a typically phloroglucinol derivative which extracted from D. fragrans and has been reported to exert anti-fungal activities against several dermatophytes.

AIM OF THE STUDY

This study aimed to evaluate anti-fungal and anti-biofilm activity of isoflavaspidic acid PB on planktonic and biofilm growth of dermatophytes and explore possible mechanisms of anti-biofilm.

MATERIALS AND METHODS

Minimal inhibitory concentrations (MIC) and minimal fungicidal concentrations (MFC) of isoflavaspidic acid PB against 25 isolates of dermatophytes were determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 method. The effects of isoflavaspidic acid PB on dermatophytes biofilm formation and pre-formed biofilm were assessed by 2.3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[carbonyl (phenylamino)]-2H-tetrazolium hydroxide (XTT) assay. Morphology of mature biofilm were observed by Scanning Electron Microscope (SEM). Biomass, exopolysaccharide and ergosterol content of mature biofilm were analyzed by gravimetric analysis, anthranone sulfuric acid method and Ultra Performance Liquid Chromatography (UPLC) assay respectively.

RESULT

The MIC and MFC ranges of isoflavaspidic acid PB against 25 isolates of dermatophytes were 20-80 μg/mL and 40-80 μg/mL respectively. Isoflavaspidic acid PB (2 MIC) inhibited not only Trichophyton biofilm formation (54.8% ∼ 81.2%) but also the metabolic activity of mature biofilm (20.7% ∼ 44.2%). The result of SEM showed that isoflavaspidic acid PB (8 MIC) could destroy the morphology of hyphae seriously. Comparing with control group, biomass, exopolysaccharide and ergosterol content of the mature biofilm under isoflavaspidic acid PB (8 MIC) were significantly decreased (P < 0.01).

CONCLUSION

Isoflavaspidic acid PB had anti-fungal and fungicidal activities against dermatophytes. Isoflavaspidic acid PB could inhibit the biofilm of Trichophyton. The mechanism might be related to the decline of the biofilm biomass, exopolysaccharide and ergosterol content. These results showed that isoflavaspidic acid PB could be explored for promising anti-biofilm drugs.

Ex vivo biofilm-forming ability of dermatophytes using dog and cat hair: an ethically viable approach for an infection model

The aim of this study was to establish an ex vivo model for dermatophyte biofilm growth, using hair from dogs and cats. Strains of Microsporum canis, M. gypseum, Trichophyton mentagrophytes and T. tonsurans were assessed for in vitro and ex vivo biofilm production. All T. mentagrophytes and T. tonsurans isolates and 8/12 M. canis and 1/7 M. gypseum isolates formed biofilms in vitro, while all tested isolates presented biofilm growth on ex vivo models. T. mentagrophytes and M. canis formed more homogeneous and better-structured biofilms with greater biomass production on cat hair but T. tonsurans formed more biofilm on dog hair. Confocal and scanning electron microscopy demonstrated fungal hyphae colonizing and perforating the hair shaft, abundant fungal conidia, biofilm extracellular matrix and biofilm water channels. The present study demonstrated an ex vivo model for the performance of studies on biofilm formation by dermatophytes, using dog and cat hair.

Antifungal and antioxidant activities of Coleonema album and C. pulchellum against skin diseases

CONTEXT

Coleonema album (Thunb) Bart. & H. L. Wendl (Rutaceae) has been used in the formulation of skincare products, and the Khoisan people rub it on their skin to add luster. Coleonema pulchellum I. Williams has received less attention in the South African traditional medicine.

OBJECTIVE

This study investigates the antifungal and antioxidant activities of C. album and C. pulchellum essential oil (EO) and leaf extracts; and analyzes the chemical components of their EOs.

MATERIALS AND METHODS

Antifungal activity of leaf extracts was determined using the microdilution method with griseofulvin and ketoconazole as controls. Antifungal capacity of EO was investigated using the 'Volatile release plate method'. Trichophyton rubrum (ATCC 28188) and T. mentagrophytes (ATCC 9533) mycelia (0.3 cm diameter) were placed on fresh yeast malt agar in Petri dishes with filter paper (impregnated with 20 μL of EO) on the lid for direct exposure to EO volatiles while plates without EO were used as controls. The incubation time was seven days. Antioxidant activities of the leaf extracts were determined.

RESULTS

Methanol leaf extract of C. pulchellum inhibited the growth of three fungi tested with MIC values of 195, 391 and 49 μg/mL for Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum gypseum, respectively. Terpenes formed the major components of the EO. The EO from both plants inhibited the growth of T. rubrum in vitro.

DISCUSSION AND CONCLUSION

This study revealed the therapeutic value of C. pulchellum. Coleonema album and C. pulchellum should be considered as potential plants for skin ointment from natural origin.

Boric Acid Inhibition of Trichophyton rubrum Growth and Conidia Formation

Trichophyton rubrum is a common human dermatophyte that is the causative agent of 80-93% of fungal infections of the skin and nails. While dermatophyte infections in healthy people are easily treatable with over-the-counter medications, such infections pose a higher risk for patients with compromised immune function and impaired regenerative potential. The efficacy of boric acid (BA) for the treatment of vaginal yeast infections prompted an investigation of the effect of BA on growth and morphology of T. rubrum. This is of particular interest since BA facilitates wound healing, raising the possibility that treating athlete's foot with BA, either alone or in combination with other antifungal drugs, would combine the benefits of antimicrobial activity and tissue regeneration to accelerate healing of infected skin. The data presented here show that BA represses T. rubrum growth at a concentration reported to be beneficial for host tissue regeneration. Oxygen exposure increases BA toxicity, and mycelia growing under BA stress avoid colonizing the surface of the growth surface, which leads to a suppression of aerial mycelium growth and surface conidia formation. BA penetrates into solid agar matrices, but the relative lack of oxygen below the substrate surface limits the effectiveness of BA in suppressing growth of embedded T. rubrum cells.

BIOLOGICAL PROPERTIES AND CHEMICAL COMPOSITION OF JATROPHA NEOPAUCIFLORA PAX

Background:

Ethnopharmacological relevance. Jatropha neopauciflora (Pax) is an endemic species of the Tehuacan- Cuicatlan Valley, Mexico. This species has long been used as a remedy to alleviate illnesses of bacterial, fungal and viral origin. Aim of the study. Experimentally test the traditional use of Jatropha neopauciflora in Mexican traditional medicine.

Materials and methods.:

The methanol extract (MeOH1), of Jatropha neopauciflora (Euphorbiaceae) was obtained by maceration. Next, the methanol (MeOH2) and hexane (H) fractions were obtained. The essential oil was obtained by hydro- distillation. The extract, fractions and essential oil were analyzed by GC-MS. The antimicrobial activity was measured by the disc diffusion agar and radial inhibition growth methods.

Results:

The extract and fractions showed antibacterial activity against eleven strains (five Gram-positive and six Gram- negative) and a bacteriostatic effect in the survival curves for Staphylococcus aureus and Vibrio cholerae. The extract and fractions were also shown to have antifungal activity, particularly against Trichophyton mentagrophytes (CF₅₀ = MeOH1: 1.07 mg/mL, MeOH2: 1.32 mg/mL and H: 1.08 mg/mL). The antioxidant activity of MeOH1 (68.6 μg/mL) was higher than for MeOH2 (108.1 μg/mL). The main compounds of the essential oil were β-pinene, 1,3,8-p-menthatriene, ledene, m- menthane, linalyl acetate and 3-carene. The main compounds of MeOH1 were β-sitosterol, lupeol and pyrogallol; the main compounds of MeOH2 were β-sitosterol, spathulenol, coniferyl alcohol and lupeol; and the main compounds of H were β-sitostenone, γ-sitosterol and stigmasterol.

Conclusions:

This study indicates that Jatropha neopauciflora is a potential antibacterial and antifungal agent.

Antifungal properties of hypericin, hypericin tetrasulphonic acid and fagopyrin on pathogenic fungi and spoilage yeasts

CONTEXT

The role of hypericin-mediated photodynamic antimicrobial properties on pathogenic fungi and photodynamic therapy for human cancer cells is known. Antifungal properties of Hypericum perforatum L. (Hypericaceae) and Fagopyrum esculentum Moench. (Polygonaceae) extracts were also studied. The different polarities of solvents can cause complication in the identification of antifungal effects of separate biologically active compounds. In recent experimental work, we compared antifungal properties of purified hypericin, hypericin tetrasulphonic acid (hypericin + S) and fagopyrin, which is analogue of hypericin.

OBJECTIVE

The antifungal properties of aromatic polyketide derivatives such as hypericin, hypericin + S and fagopyrin on the selected pathogenic fungi and spoilage yeasts have been studied.

MATERIALS AND METHODS

The antifungal properties of hypericin, hypericin + S and fagopyrin were determined using the broth microdilution method against a set of pathogenic fungi and spoilage yeasts including: Microsporum canis, Trichophyton rubrum, Fusarium oxysporum, Exophiala dermatitidis, Candida albicans, Kluyveromyces marxianus, Pichia fermentans and Saccharomyces cerevisiae. The tested concentrations of hypericin, hypericin + S and fagopyrin ranged from 750 to 0.011 μg/mL and MIC values were evaluated after 48 h incubation at 30 °C.

RESULTS

The results confirm different antifungal properties of hypericin, hypericin + S and fagopyrin on the selected pathogenic fungi and spoilage yeasts. For pathogenic fungi, the minimum inhibitory concentrations of hypericin ranged 0.18-46.9 μg/mL, hypericin + S 0.18-750 μg/mL and fagopyrin 11.7-46.9 μg/mL. For spoilage yeasts, the MICs of hypericin and hypericin + S ranged 0.18-46.9 and 0.011-0.73 μg/mL, respectively.

DISCUSSION AND CONCLUSION

The results obtained herein indicate that various chemical structures of hypericin, hypericin + S and fagopyrin can develop different antifungal properties.

Trichphyton violaceum and T. soudanese: re-emerging pathogens in Italy, 2005-2013

Dermatomycoses due to Trichophyton violaceum are described in Mediterranean Countries, North Africa and in the Horn of Africa where T. soudanense is present too, but it was rare until few years ago in Italy. Aim of the present study was to evaluate an Italian multicenter 9 year (2005-2013) experience concerning these re-emerging pathogens. Fifty three fungal strains were sent from clinical laboratories to the Medical Mycology Committee (CoSM)--Italian Association of Clinical Microbiology (AMCLI) for mycological confirmation. Strains were identified as T. violaceum (23) and T. soudanense (30) by phenotypic and genotypic methods. These dermatophytes present epidemiological (high rate of inter-human transmission, high risk among adopted children coming from countries of either the Horn of Africa or Sub-Saharan Africa also in outbreaks of tinea capitis) and clinical peculiarities (reduced alopecia, presence of exudative lesions) confirming the originality of these "imported" dermatophyte infections.

Intravenous Iron Sucrose Therapy in Iron Deficiency Anemia in Antenatal and Postnatal Patients

INTRODUCTION

Dermatophytosis is a common superficial fungal infection of the skin, hair and nails caused by Trichophyton, Microsporum and Epidermophyton dermatophytic species. Identification of causative dermatophytic species tend to vary with time and place and antifungal sensitivity is of epidemiological concern as well as significant for the treatment with precision at the current scenario of increasing antifungal resistance. The objectives was to study clinicomycological profile and antifungal sensitivity pattern of commonly used azoles in dermatophytosis.

METHODS

The prospective analysis of 145 clinically suspected cases of dermatophytosis was conducted from January 2014 to January 2015 at Department of Dermatology of COMS, Bharatpur, Chitwan, Nepal. Cases were evaluated and data recorded as per proforma. Samples were collected for microscopy and culture from skin, hair and nail. Antifungal sensitivity pattern was evaluated by standard disk diffusion technique.

RESULTS

Maximum numbers of cases with dermatophytosis were observed between June to September with male to female ratio of 1.4:1. The youngest patient was 3 years and the oldest was 76 years. Tinea corporis (25.5%) was the dominant clnical type observed. Overall direct microscopy (KOH) positivity and culture positivity was 64.8% and 57.2% respectively. Predominant species of dermatophyte isolated was T. mentagrophyte (23.4%). Out of five antifungals used in our study, fluconazole and ketoconazole were found 100% resistant.

CONCLUSIONS

This study highlighted the increasing resistance of the antifungals, which is responsible for the treatment failure in dermatophye infections.

Carum copticum and Thymus vulgaris oils inhibit virulence in Trichophyton rubrum and Aspergillus spp

Emergence of drug-resistant strains has demanded for alternative means of combating fungal infections. Oils of Carum copticum and Thymus vulgaris have long been used in ethnomedicine for ailments of various fungal infections. Since their activity has not been reported in particular against drug-resistant fungi, this study was aimed to evaluate the effects of oils of C. copticum and T. vulgaris on the growth and virulence of drug-resistant strains of Aspergillus spp. and Trichophyton rubrum. The gas chromatography-mass spectrometry analysis revealed thymol constituting 44.71% and 22.82% of T. vulgaris and C. copticum, respectively. Inhibition of mycelial growth by essential oils was recorded in the order of thymol > T. vulgaris > C. copticum against the tested strains. RBC lysis assay showed no tested oils to be toxic even up to concentration two folds higher than their respective MFCs. Thymol exhibited highest synergy in combination with fluconazole against Aspergillus fumigatus MTCC2550 (FICI value 0.187) and T. rubrum IOA9 (0.156) as determined by checkerboard method. Thymol and T. vulgaris essential oil were equally effective against both the macro and arthroconidia growth (MIC 72 μg/mL). A > 80% reduction in elastase activity was recorded for A. fumigatus MTCC2550 by C. copticum, T. vulgaris oils and thymol. The effectiveness of these oils against arthroconidia and synergistic interaction of thymol and T. vulgaris with fluconazole can be exploited to potentiate the antifungal effects of fluconazole against drug-resistant strains of T. rubrum and Aspergillus spp.

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.

Infection of keratinocytes with Trichophytum rubrum induces epidermal growth factor-dependent RNase 7 and human beta-defensin-3 expression

Human keratinocytes are able to express various antimicrobial peptides (AMP) to protect the skin from exaggerated microbial colonization and infection. Recently, in vitro growth-inhibiting activity of the skin-derived AMP psoriasin, RNase 7 and human beta-defensin (hBD)-2 against dermatophytes such as Trichophyton (T.) rubrum have been reported. To evaluate whether keratinocytes are able to respond to T. rubrum infection by an induced expression of AMP we exposed primary keratinocytes to living conidia of T. rubrum. This led to conidia germination and mycelial growth which was paralleled by a strong gene induction of the skin-derived AMP RNase 7 and hBD-3. Gene expression of the AMP psoriasin (S100A7) and hBD-2 were only slightly induced. The T. rubrum-mediated RNase 7 gene induction was accompanied by increased secretion of RNase 7. Parallel treatment of the keratinocytes with T. rubrum and the cytokine combination IL-17A/IFN-γ resulted in synergistic induction of RNase 7 and hBD-3 expression. Since patients receiving therapy by inhibition of the epidermal growth factor receptor (EGFR) more often suffer from dermatophytoses we investigated whether EGFR may be involved in the T. rubrum-mediated RNase 7 and hBD-3 induction. Primary keratinocytes incubated with an EGFR blocking antibody as well as with the EGFR antagonist AG1478 showed a significantly diminished RNase 7 and hBD-3 induction upon exposure of the keratinocytes to T. rubrum indicating that EGFR is involved in the T. rubrum-mediated induction of RNase 7 and hBD-3. The growth of T. rubrum in vitro was inhibited by hBD-3 in a dose-dependent manner suggesting that hBD-3 may contribute to cutaneous innate defense against T. rubrum. Taken together our data indicate that keratinocytes are able to initiate a fast defense response towards T. rubrum by the increased expression of AMP active against T. rubrum. A dysregulation of AMP may contribute to chronic and recurring dermatophytoses.

Decreasing incidence of Trichophyton mentagrophytes in Korea: analysis of 6,250 cases during the last 21-year-period (1992-2012)

Trichophyton mentagrophytes is the second common dermatophyte in Korea. However, few reports have been issued on the epidemiological and mycological characteristics of T. mentagrophytes in Korea based on long-term, large-scale study. The purpose of this study was to elucidate the epidemiological and mycological characteristics of T. mentagrophytes in Korea. During the 21-yr-period from 1992 to 2012, 6,250 patients with T. mentagrophytes were surveyed to determine annual incidence and the distribution of subjects by age, sex, season, involved sites, and place of residence. T. mentagrophytes infections were confirmed by fungal culture. In addition, the colony appearance of T. mentagrophytes was classified as granular, persicolor, powdery, or downy. Epidemiological analysis showed that annual incidence reached a peak in 2005, and then gradually decreased. T. mentagrophytes infection was most common in July, and was found predominantly in middle-aged adults, especially in those in their forties. Mycological analysis showed a powdery colony appearance was the most common, followed by persicolor and granular colonies. Toewebs were most frequently involved. This investigation on T. mentagrophytes provides insights into its incidence and characteristics.

Human pathogenic fungus Trichophyton schoenleinii activates the NLRP3 inflammasome

The fungus Trichophyton schoenleinii (T. schoenleinii) is the causative agent of Trichophytosis and Tinea favosa of the scalp in certain regions of Eurasia and Africa. Human innate immune system plays an important role in combating with various pathogens including fungi. The inflammasome is one of the most critical arms of host innate immunity, which is a protein complex controlling maturation of IL-1β. To clarify whether T. schoenleinii is able to activate the inflammasome, we analyzed human monocytic cell line THP-1 for IL-1β production upon infection with T. schoenleinii strain isolated from Tinea favosa patients, and rapid IL-1β secretion from THP-1 cells was observed. Moreover, applying competitive inhibitors and gene specific silencing with shRNA, we found that T. schoenleinii induced IL-1β secretion, ASC pyroptosome formation as well as caspase-1 activation were all dependent on NLRP3. Cathepsin B activity, ROS production and K⁺ efflux were required for the inflammasome activation by T. schoenleinii. Our data thus reveal that the NLRP3 inflammasome plays an important role in host defense against T. schoenleinii, and suggest that manipulating NLRP3 signaling can be a novel approach for control of diseases caused by T. schoenleinii infection.

Trichophyton rubrum suppurative tinea of the bald area of the scalp

An 83-year-old man presented with an approximately 1-year history of an extensive inflammatory purulent crusted lesion in the bald area of the scalp diagnosed as tinea caused by Trichophyton rubrum. The scalp biopsy specimen showed suppurative folliculitis with perifollicular abscesses in upper dermis, and periodic acid-Schiff-positive fungal elements within the hair follicles and in the hyperkeratotic horny layer. The infection probably spread from diseased fingernails. A cure of the scalp lesion was achieved 2 months after starting daily oral treatment with 250 mg terbinafine. To our knowledge, the case presented is the first in which a suppurative abscess-forming T. rubrum infection of the bald area of the scalp in an immunocompetent man has been described.

Tinea capitis caused by Trichophyton soudanense and Microsporum audouinii in an adult: a case report

This report presents a rare case of tinea capitis caused by Trichophyton soudanense and Microsporum audouinii in a 31-year-old woman from Senegal. The patient showed atrophic skin lesions causing cicatricial alopecia, scarring being caused by two aetiological agents uncommon in Spain.

[Establishing an experimental guinea pig model of dermatophytosis Using Trichophyton rubrum]

OBJECTIVE

To construct an animal model infected by Trichophyton rubrum.

METHODS

Three different strains of Trichophyton rubrum were separated from clinical specimen for the infection of guinea pigs. Corticosteroids were given before and after the construction of animal model to facilitate the infection. Direct microscopy, culture, and histopathologic methods were adopted to verify the construction.

RESULTS

Ten days after the inoculation of Trichophyton rubrum, with the intervention of corticosteroid, the guinea pigs were examined. Prominent scales and inflammation could be seen on the inoculation site of the Trichophyton rubrum infected guinea pig. Scales and hairs of Trichophyton rubrum infected guinea pig dealt with 10% potassium hydroxide, hypha out of the hair and microconidia or hypha in the hair shaft could be seen. Seven days after the inoculation of scales and hair on SDA plate, cultures of Trichophyton rubrum showed that the colonial morphology were identical to the original dermatophytes. PAS staining of infected guinea pig skin tissue showed that hypha and microconidia could be seen in the infundibula and hair root.

CONCLUSION

With the intervention of corticosteroid, a stable guinea pig model infected by Trichophyton rubrum were successfully constructed.

Comparison between gene expression of conidia and germinating phase in Trichophyton rubrum

Trichophyton rubrum is a dominating superficial dermatophyte, whose conidial germination is correlated to pathopoiesis and a highly important developmental process. To investigate the changes of physiology, biochemistry and cytology during the germination, we selected 3364 function identified ESTs from T. rubrum cDNA library to construct cDNA microarrays, and compared the gene expression levels of conidia and germinating phase. Data analysis indicated that 335 genes were up-regulated during the germination, which mainly encoded translated, modified proteins and structural proteins. The constituents of cell wall and cell membrane were synthetized abundantly, suggesting that they are the foundation of cell morphogenesis. The ingredients of the two-component signal transduction system were up-regulated, presuming that they were important for the conidial germination. Genes of various metabolic pathways were expressed prosperously, especially the genes that participated in glycolysis and oxidative phosphorylation were up-regulated on the whole, demonstrating that in the environment with sufficient oxygen and glucose, conidia obtained energy through aerobic respiration. This paper provides important clues which are helpful to understanding the changes in gene expression, signal conduction and metabolism characteristics during T. rubrum conidial germination, and possess significant meaning to the study of other superficial dermatophytes.

Trichophyton mentagrophytes sive interdigitale? A dermatophyte in the course of time

Originally, the Trichophyton (T.) mentagrophytes complex distinguished between the anthropophilic subspecies T. mentagrophytes var. interdigitale, T. mentagrophytes var. nodulare (synonym T. krajdenii), and T. mentagrophytes var. goetzii and the zoophilic subspecies T. mentagrophytes var. granulosum (rodents), T. mentagrophytes var. erinacei (hedgehog), and T. mentagrophytes var. quinckeanum (mice). In addition, two sexual species (teleomorph) of this complex are known. These are Arthroderma (A.) benhamiae Ajello and Cheng 1967 and Arthroderma vanbreuseghemii Takashio 1973. According to recent molecular studies,the species T.mentagrophytes is synonymous with only the zoophilic subspecies T.mentagrophytes var. quinckeanum which is rare in Western Europe. The anthropophilic subspecies of T. mentagrophytes, as well as many of the zoophilic strains, formerly differentiated as var. mentagrophytes or var. granulosum, are indistinguishable and are now designated T.interdigitale. The morphological differentiation between anthropophilic and zoophilic T. interdigitale strains by classical microscopical and biochemical methods is often problematic. In particular, it is impossible to differentiate between the zoophilic strains of T. interdigitale, T. mentagrophytes, and the Trichophyton anamorph of A. benhamiae. In these cases, molecular identification methods may be applied to answer epidemiological, taxonomical and therapeutic questions.

The pH signaling transcription factor PacC mediates the growth of Trichophyton rubrum on human nail in vitro

We report here the isolation, molecular cloning and initial characterization of the Trichophytonrubrum pacC gene, which encodes a putative protein that is homologous to the PacC/Rim101p family of pH signaling transcription regulators. The promoter region of the T. rubrumpacC gene contains four recognition sites 5'-GCCAAG-3' for the PacC protein, suggesting that the transcription of this gene itself could be induced under alkaline growth conditions. The enhanced expression profile of the T. rubrumpacC gene in an alkaline environment was confirmed by Northern blotting analysis. We also report that the disruption of pacC gene decreased both the secretion of keratinolytic proteases and the ability of the mutant pacC-1 to grow on human nail fragments as the sole source of nutrition, i.e., growth of the dermatophyte T. rubrum appear to be related to molecular events which depend on the action of protein PacC.

A Study on Stability of Phenotype and Genotype of Trichophyton rubrum

OBJECTIVE

To explore the stability of phenotype and genotype in Trichophyton rubrum.

METHODS

All the strains were cultured on Sabouraud's dextrose agar slopes, and identified to species level. Strains isolated recently were subcultured on Sabouraud agar slopes four times at an interval of 4 weeks. DNA was extracted with CTAB method. A probe consisting of 3' end of 18S rDNA, adjacent ITS1, 5.8S rDNA and ITS2 regions was amplified from template DNA of the T. rubrum standard strain using fungal universal primers NS5 and ITS4, labelled by P32 and hybridized with EcoR I-digested T. rubrum genomic DNA.

RESULTS

(1) Four phenotypes were isolated from 207 T. rubrum strains, with downy type (45.4%) in the first place, and granular type not found. After 1 year of conservation, 54 strains showed morphological variations with the total variation rate of 26.1%. (2) Eleven strains showed variations in colony morphology or pigment upon subculture. (3) AP-PCR analysis of 10 T. rubrum isolates and one T. rubrum standard strain showed similar DNA patterns with main bands at 2.2, 1.7, 1.3, 0.9 and 0.7 kb. No changes in DNA pattern were found upon subculture. (4) Hybridization analysis revealed that all the 11 T. rubrum strains presented three bands and were identified into two types (2.4, 3.9, 5.9 kb and 2.4, 4.4, 6.5 kb). No changes in band pattern were found upon subculture.

CONCLUSIONS

Phenotype of T. rubrum was instable and the colonial morphology and pigment easily changed during conservation or subculture, while its genotype was relatively stable.

Trichophyton eboreum sp. nov. isolated from human skin

An unusual dermatophyte was isolated from the plantar scales of a human immunodeficiency virus-positive man with tinea pedis. Morphology, physiology, and molecular data provided evidence to support the new species Trichophyton eboreum. This dermatophyte is characterized by rapid growth on common mycological media, a flat powdery off-white colony, formation of clavate microconidia, smooth- and thin-walled cylindrical or club-shaped macroconidia with two to nine cells, the presence of hook-shaped hyphae, the production of cleistothecium-like structures and spiral hyphae in older cultures, positive hair perforation, the absence of pigmentation on potato glucose agar, the absence of a requirement for vitamins, a weak positive urease reaction, no growth at 37 degrees C, resistance to 5% NaCl, resistance to fluconazole, good growth on human epidermal keratin, and the production of various enzymes on different media by the API-ZYM test. More than 5% divergence from any known species of dermatophyte was revealed by sequence analysis of the internal transcribed spacer of the rRNA gene.

Prevalence of tinea capitis in Ethiopian schoolchildren

The prevalence of dermatophytosis and the spectrum of dermatophyte species were determined in children attending two schools in Addis Ababa, Ethiopia. Demographic and clinico-dermatological data were collected. Specimens were taken for microscopy and culture from all suspected lesions. Dermatophyte species were identified by morphology and biochemical tests, supplemented by sequencing of the rDNA ITS 2 region in selected isolates. From the Biruh Tesfa Elementary School (BTES) 824 students, and from Mount Olive Academy (MOA) all 124 students, were included. In BTES 513 (62.3%) students were clinically diagnosed with dermatophytosis, 463 (90.3 %) of them with tinea capitis. In 200 consecutive samples from BTES, and in 66 from MOA, 75 and 62%, respectively, contained fungal elements at microscopy. From BTES, 163/496 (33%) samples were culture-positive, of which 149 (91.4%) grew with dark purple colonies identified as Trichophyton violaceum, while 244 (49.4%) samples were contaminated. A few strains grew slowly developing white to cream colonies, two were identified as T. verrucosum, and 12 as white T. violaceum. From MOA 44 (66.7%) of samples were culture-positive, 38 (87%) were identified as T. violaceum, and one (2.3%) as T. verrucosum, while 33% showed no growth. Four white isolates of T.violaceum were confirmed by DNA-sequencing. Dermatophytosis was thus diagnosed in 55-62% of children screened at two schools of different socioeconomic standards in the Ethiopian capital. Trichophyton violaceum constituted 87-90% of all isolates. White variants of T. violaceum were diagnosed in 16 cases.

Biological control of dermatophytic fungus Trichophyton species by Bacillus subtilis

A potent Bacillus subtilis-2 isolated from soil samples, showed 14 mm inhibition zone by spot inoculation method and 22 mm inhibition zone by well agar diffusion method against pathogenic test fungii. i.e. Trichophyton species. Among four media tested, the maximum growth and antibiotic production was found in trypticase soya broth (TSB) medium at 37 degrees C, pH 7 and 48 hrs of incubation. The MIC of antifungal substance was 35 microl/ml. The isolated Bacillus subtilis -2 has strong antifungal activity against dermatophytic fungi Trichophyton sp. and requires chemical characterization for its bioactive principle.

The influence of surface carbohydrates during in vitro infection of mammalian cells by the dermatophyte Trichophyton rubrum

In order to better understand the role played by surface glycoconjugates during host cell adhesion and endocytosis of Trichophyton rubrum, we looked for the presence of carbohydrate-binding adhesins on the microconidia surface and their role on cellular interaction with epithelial and macrophages cells. The interaction of T. rubrum with chinese hamster ovary epithelial cells and their glycosylation-deficient mutants demonstrated a higher adhesion index in Lec1 and Lec2 mutants, that express mannose and galactose, respectively. Endocytosed fungi were shown preferentially in Lec2 cells. Addition of the carbohydrates to the interaction medium, pretreatment with lectins and with sodium periodate decreased the adhesion and endocytic index for all mutants. The ability of the fungus to penetrate into mammalian cells was confirmed in experiments using macrophages treated with cytochalasin D. Flow cytometric analysis showed that this fungus recognizes mannose and galactose. The binding was inhibited by the addition of methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside, and showed higher fluorescence intensity at 37 than at 28 degrees C. Trypsin treatment and heating of the cells reduced the binding, suggesting a (glyco) protein nature for the microconidia adhesins. The presence of lectin-like molecules in fungus cell could be observed by scanning electron microscopy of the fungus incubated with colloidal-gold labeled neoglycoproteins. Our results suggest that T. rubrum has the ability to invade mammalian cells and expresses carbohydrate-specific adhesins on microconidia surface that recognize mannose and galactose. These adhesins may play an important role on the adhesion and invasion of the fungus during the infectious process of dermatophytosis.

Arthroconidial formation in Trichophyton raubitschekii

Arthroconidia produced by dermatophytic fungi are considered to be the primary cause of skin and nail infections in humans and animals. Trichophyton rubrum is currently the most common cause of tinea pedis all over the world. The common form of T. rubrum produces a cottony colony in cultures that is characteristically low in conidia formation. The attempts to produce arthroconidia in T. rubrum have shown little success so far. Recently, Trichophyton raubitschekii, an anthropophilic dermatophyte prevalent in Asia, Africa, and the Mediterranean, has been recognized as a variant of T. rubrum. In cultures, T. raubitschekii is characterized by a granular colony form, and an abundance of both micro- and macroconidia. The present study reveals a predominance of arthroconidia in two T. raubitschekii cultures isolated from clinical materials. These isolates were able to maintain arthroconidiation in bimonthly subcultures throughout the entire course of this study. The growth parameters for in vitro cultivation of arthroconidia are described here. Arthroconidia prepared from T. raubitschekii cultures showed greater than 95% germination within 21 h of suspension in phosphate-buffered saline. The availability of arthroconidia in T. raubitschekii cultures appears to offer a practical means of characterizing infective cells in T. rubrum.

The epidemiology and mating behavior of Arthroderma benhamiae var. erinacei in household four-toed hedgehogs (Atelerix albiventris) in Japan

An epidemiological survey of Trichophyton mentagrophytes var. erinacei in the household hedgehog and other rodents was made between January 17, 2002 and February 28, 2002 in Japan. Quills and hairs were collected from sources identified via the internet. The fungus was isolated only from the quills of four-toed hedgehogs (7/18; 39%) from Kanto to Kyushu regions. Isolates were examined morphologically, physiologically and genetically, and identified as T. mentagrophytes var. erinacei anamorph. The isolates were also genetically compared with European hedgehog (Erinaceus europeus)-borne T. mentagrophytes var. erinacei and Kenyan hedgehog (Aterelix albiventris)-borne Arthroderma benhamiae, and their genotypes of the ITS1-5.8S-ITS2 rDNA were all identical. The isolates were crossed with A. benhamiae Americano-European race and African race, A. vanbreuseghemii and A. simii, with the result that they mated only with African race (+) or (-). Mating types of the isolates were (+) in 6 isolates and (-) in one. An intra-isolate mating between one of the 6 plus isolates and the minus one formed abundant mature gymnothesia, the mating type ratio of the F1 progeny was approximately 1:1, and the sib crossings of F1 progeny produced abundant fertile gymnothesia. The present study revealed that the intra-Japanese hedgehog-borne isolate crossing showed complete fertility and that the sexual degeneration pointed out by Takashio (Mycologia 71: 968-976, 1979) did not exist. Two pairs of mating, (+) and (-) mating types of Japanese isolates with (-) and (+) tester strains of A. benhamiae African race formed less gymnothesia, mating type ratios were unbalanced, and sib crossings of F1 progeny produced small gymnothesia containing a low number of asci, pseudogymothesia, or none, respectively. These results show that A. benhamiae var. erinacei, the teleomorph of T. mentagrophytes var. erinacei, belongs to a different mating group (e.g. hedgehog race) than the Americano-European and African races in A. benhamiae.

The role of surface carbohydrates on the interaction of microconidia of Trichophyton mentagrophytes with epithelial cells

The presence of carbohydrate-binding adhesins on the microconidia of Trichophyton mentagrophytes surface and their role on cellular interactions were investigated. Flow cytometry showed that this fungus recognizes the sugars mannose and galactose. The binding was inhibited by the addition of methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside, and showed higher fluorescence intensity at 37 degrees C than 28 degrees C. Trypsin treatment and heating of the cells reduced the binding, suggesting a (glyco) protein nature of the microconidia adhesin. The interaction of the fungus to Chinese hamster ovary epithelial cells and its glycosylation-deficient mutants demonstrated a higher adhesion index in Lec1 and Lec2 mutants, which express mannose and galactose, respectively, as the terminal carbohydrate on the cell surface. Endocytosed fungi were shown preferentially in Lec2 cells. Addition of the carbohydrates methyl alpha-D-mannopyranoside and methyl alpha-D-galactopyranoside to the interaction medium, pretreatment of Lec1 and Lec2 cells with lectins Concanavalina A and Arachis hypogaea and pretreatment with sodium periodate decreased the adhesion and the endocytic index. Examination of thin section by transmission electron microscopy showed that after fungal ingestion by Lec2 cells the fungi are enclosed in a 'loose'-type vacuole while the other cells are found within a 'tight'-type membrane-bound cytoplasmic vacuole. Our results suggest the occurrence of carbohydrate-specific adhesins on microconidia surface that recognize mannose and galactose. This may have a role in the adhesion process during the infectious process of dermatophytosis.

[The influence of urea, ammonia and nitrate as they affect growth and viability of Trichophyton verrucosum]

Six strains of Trichophyton verrucosum were used in a test to determine effects of urea and sodium nitrate on their growth. Despite having urease activity, the strains failed to utilize the urea and sodium nitrate for their growth. Moreover, the organisms were killed if large amounts of these nitrogen compounds and ammonia were added to the medium. These nitrogen compounds, distributed in cattle breeding soil, inhibited the growth of T. verrucosum. Thus, soil in cattle breeding environments does not seem to be a reservoir of this pathogen.

Arthroconidia as vectors of dermatophytosis

The characteristic macro- and microconidia produced by dermatophytes in cultures and those living as saprobes are not produced in any dermatophyte lesions observed to date. However, arthroconidia, defined as a genetically programmed disarticulation of septate hyphae to produce a chain of conidia, are produced by dermatophytes, both in culture and in lesions, under certain predisposing conditions. Arthroconidia are seen, for example, within nail-bed infections caused by Trichophyton rubrum; within nail-plate infections caused by Trichophyton mentagrophytes interdigitale; and in the infections of scalp hair by soil or geophilic dermatophytes, where chains of arthroconidia form near or on the surface of the infected hairs. Dr. Rashid discusses his electron microscope studies of the adherence and germination of arthroconidia and the penetration of the germ tubes and initial hyphae into the stratum corneum.

Factors involved in producing a sustained experimental dermatophyte infection (Trichophyton mentagrophytes)

Dr. Jones applied different concentrations of living dermatophyte spores to the surface of uninfected skin under occluded conditions. He then followed the subjects to observe any developing infection and determine the minimum number of spores needed to induce infection.

The boosted antifungal topical treatment (BATT) for onychomycosis

Despite promising pharmacodynamic and pharmacokinetic profiles, modern antifungals exhibit limited efficacy in the treatment of onychomycoses. The clinical and mycological data are far from reaching a complete cure even after long-course treatments extending over many months. After reviewing the histological presentation of onychomycoses, one of the main reasons for treatment failure and disease recurrence appears to be the presence of dormant chlamydospores and arthroconidia inside the infected nail plate. Accordingly, we present a novel concept in onychomycosis treatment. It consists of the combination of an antifungal with a device boosting germination of fungal propagules in order to render these cells more responsive to treatment. Preliminary results of a pilot study support such a concept.

Molecular taxonomy of the Trichophyton rubrum complex

The validity of taxa around Trichophyton rubrum was evaluated by a combination of phenetic and molecular methods. Morphological and physiological features were compared to results of sequencing of the internal transcribed spacer region of the ribosomal operon, PCR fingerprinting, and amplified fragment length polymorphism analysis. The 15 species and varieties investigated (Trichophyton circonvolutum, Trichophyton fischeri, Trichophyton fluviomuniense, Trichophyton glabrum, Trichophyton gourvilii, Trichophyton kanei, Trichophyton kuryangei, Trichophyton megninii, Trichophyton pedis, Trichophyton raubitschekii, Trichophyton rodhaini, Trichophyton rubrum var. nigricans, Trichophyton soudanense, Trichophyton violaceum var. indicum, and Trichophyton yaoundei) were reclassified or synonymized as T. rubrum or T. violaceum.

Adhesion of dermatophytes to healthy feet and its simple treatment

At several public baths, we isolated dermatophytes from the soles of healthy volunteers by a new direct isolation method (foot-press culture method). We confirmed that a public bath is one of major sources of infection of dermatophytes. We showed that simple treatments such as (i) wiping the sole with a towel; (ii) washing with soap; (iii) 100 steps on another mat; and (iv) holding the foot up for an hour, significantly reduced the fungi on the soles of six healthy volunteers. These treatments may be effective for prevention of tinea pedis.

[Effect of temperature, humidity and minor injury to the penetration of dermatophytes into human stratum corneum]

We evaluated the minimum period for penetration of Trichophyton mentagrophytes into human stratum corneum using an experimental model of tinea pedis. Fungal elements were applied to the surface of stratum corneum which were obtained from a healthy human heel, and samples were incubated under a designated condition of temperature and humidity. Thirty-five degrees, which is the approximate temperature of the surface of human skin, seemed more suitable for penetration than 27C. The result also indicated that humidity was a more significant factor than temperature. In the following examination using T. mentagrophytes and T. rubrum, the minimum period for penetration at 100% humidity was 1 day with the former and 1.5 days with the latter. At 95% humidity, T. mentagrophytes penetrated into human stratum corneum on day 1.5 and T. rubrum penetrated on day 4. Humidity of the 4th interdigital space in daily life was calculated to be below 95% using a hygro-thermometer. Therefore, to wash the feet daily can prevent development of tinea pedis. When we applied fungal elements to a cut side of stratum corneum, fungi penetrated within a day at 100% and 95% humidity. In addition, fungi were able to penetrate at below 85% humidity, which they were unable to do when applied them to the surface side. We stress that minor injury of stratum corneum is also a significant factor of the development of tinea pedis.

Characterization of fungal spores by laser desorption/ionization time-of-flight mass spectrometry

A considerable volume of research has now been completed on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to the analysis of bacteria; however, to date no definitive studies have been made using this technique on fungi. Preliminary studies on the application of the MALDI-MS methodology, previously developed for the analysis of bacteria, to the analysis of intact fungal spores are described here. MALDI-MS and electrospray mass spectrometry enable the high molecular weight analysis of proteins, glycoproteins, oligosaccharides and oligonucleotides. Using MALDI-MS with bacteria has demonstrated the ability to produce 'fingerprints' of the intact cells with the ions observed being associated with the proteinaceous components of the cell wall. This paper reports the adaptation of this technique to the direct analysis of fungal cells. The high percentage of carbohydrate in the fungal cell wall indicates that the ions observed in the mass spectrometric experiments may be of carbohydrate origin. Penicillium spp., Scytalidium dimidiatum and Trichophyton rubrum have been studied in this preliminary investigation and all show individually distinctive spectra which would appear to provide a profile of the cellular material with discrete peaks being observed over the mass range 2 to 13 kDa. The spectra obtained are reproducible within the method used but, as shown in our previous studies on bacteria, washing may selectively release components from the fungal cell wall.

Alterations in spore production in Trichophyton rubrum treated in vitro with 1-amino-6-methyl-4-phenylpyrazolo[3,4-d]-1,2,3-triazole

The effects of the newly synthesized triazole, 1-amino-6-methyl-4-phenylpyrazolo[3,4-d]-1,2,3-triazole (V5), on the dermatophyte Trichophyton rubrum were tested. Optical and electron microscopy showed that the treatment suppressed the various forms of saprophytic conidia, induced the formation of chlamydospores and accelerated the formation of arthroconidia. This new triazole did not reveal any fungistatic or fungicidal activity and could not be considered as an antifungal substance.

[Experimental studies on the penetration into the human stratum corneum of the dermatophyte]

We present results on the experimental penetration of Trichophyton mentagrophytes and T. rubrum under designated condition of humidity into human stratum corneum obtained from a healthy human heelregion. When mycelia were applied to the surface side of stratum corneum and then incubated at 100 % humidity, T. mentagrophytes and T. rubrum were observed in the stratum corneum on day 1 and day 1.5, respectively. At 95% humidity, T. mentagrophytes and T. rubrum penetrated on day 1.5 and day 4, and at 90% humidity, they penetrated on day 3 and day 7, respectively. At less than 85% humidity, no fungal elements of either strain were observed in stratum corneum for up to 7 days. These datasuggest that at least 90% humidity is necessary for these two fungi to penetrate into stratum corneum within a few days. However, when T. mentagrophytes was applied to the cutting side of the stratum corneum and thenincubated at more than 70% humidity, the mycelia were able to penetrate within a day. The same results were obtained when T. rubrum was applied on the cutting side and incubated at 95 and 100% humidity. T. rubrum was also able to penetrate into the stratum corneum within several days at 70 and 80% humidity. These results may indicate that not only persistent moisture but also minor injuries of stratum corneum are the most important factors in the development of tinea pedis.

Dermatophytes and host defence in cutaneous mycoses

Dermatophytosis is the infection of keratinized tissues such as hair, nails and the stratum corneum of the skin by dermatophyte fungi. These fungi are onygenalean anamorphs and anamorphic species belonging to the genera Trichophyton, Microsporum and Epidermophyton. An important characteristic of the dermatophytes as parasites is their restriction to the dead keratinized tissues, except in rare cases where the patient is immunosuppressed. In contrast to many fungi, including normally non-pathogenic species, which can invade systemically in severely immunocompromised (e.g. neutropenic) patients, dermatophytes appear to be unable to cause systemic infection in this population. Thus, these fungi appear to have an unique interaction with the immune system. A better understanding of this interaction will contribute significantly to our knowledge of mammalian host defences.

[Dynamics of cell wall formation from Trichophyton mentagrophytes protoplast]

There is no reference to the cell wall formation during the regeneration process in dermatophyte. Having succeeded in identifying the cell wall formation system of protoplast from Trichophyton mentagrophytes I introduce here the dynamics of the regeneration of this protoplast and the formation of cell wall using ultrahigh resolution low-voltage scanning electron microscopy and transmission electron microscopy (TEM), compare to the formation of yeast cell wall. Protoplasts were formed from mycelia of T. mentagrophytes; they regenerated the cell wall substances and were followed by a network of fibrils after 4-6 hr, which developed into mature mycelia after 21 hr. A network of twisted microfibrils and rope-shaped thick fiber was seen; it was covered with a sheath-shaped structure and was created on the surface of the developing mycelium. Intrafibrillar space and the surface of thick fibers were gradually filled with amorphous particles and a mature cell wall surface was formed. This protoplast regeneration was completely inhibited by the antifungal agent, lanoconazole (2 ng/ml ). The sectioned TEM image revealed that normal mycelium having a thin cell wall developed from the abortive bead-shaped mycelium which was visible in the lose fibrous structure. Based on this result and our previos work on the ultrastructure of the mycelial surface of T. rubrum with lanoconazole, a model of the cell wall composition of Trichophyton is proposed.

Contact-sensing by hyphae of dermatophytic and saprophytic fungi

Contact-sensing or thigmotropism is the directional growth response of cells in relation to topographical guidance cues. Thigmotropism is thought to play a major role in the location of infectable sites on plants by phytopathogenic fungi and has recently been shown to be a property of hyphae in the human pathogenic fungus Candida albicans. Here we show that hyphae of the dermatophytes Epidermophyton floccosum, Microsporum canis and Trichophyton mentagrophytes reorientate their direction of growth in response to grooves and pores of membrane substrata as did hyphae of the saprophytes Mucor mucedo and Neurospora crassa. This suggests that the thigmotropic behaviour of hyphae is not a specific property of pathogens, but rather a general feature of the growth of fungal hyphae that must forage for nutrients on surfaces and within solid materials.

Isolation of Trichophyton raubitschekii in Rio de Janeiro (Brazil)

We report the first report of the isolation of Trichophyton raubitschekii in Brazil. The patients (n = 4) had typical lesions of tinca corporis. The identification of the isolates as members of this recently described species was based on morphological and physiological characteristics.

Effect of glucose and thiamine concentrations on the formation of macroconidia in dermatophytes. Occurrence of dysgonic Microsporum canis strains in Athens, Greece

Data collected from multiple trials with 110 fresh and preserved clinical isolates of Trichophyton mentagrophytes var. mentagrophytes, T. violaceum, T. rubrum, T. verrucosum, Microsporum canis and Epidermophyton floccosum revealed that production of macroconidia depends on glucose and thiamine concentrations in the medium. Optimal macroconidia production was obtained at the critical concentrations of 5 g l-1 glucose and 0.6 g l-1 thiamine when the two compounds were used in combination. The same conditions also encouraged macroconidia production in aconidial strains of T. verrucosum. Cutaneous inoculation in immunocompetent laboratory rabbits further enhanced the macroconidia producing capacity of the tested strains. Emphasis was placed on the occurrence of dysgonic/atypical strains of M. canis, which readily reverted to their typical phenotypes after growth on medium supplemented with 0.6 g l-1 thiamine, a process greatly augmented after cutaneous animal inoculation. It was verified that selective exogenous factors affect macroconidial production and that the dysgonic group of M. canis constitutes an epidemiologically significant group in the Greater Athens area. This is the first report of the occurrence of such M. canis strains from Greece.

Long-term maintenance of lyophilized fungal cultures of the genera Epidermophyton, Microsporum, Paecilomyces and Trichophyton

Twenty-six sporulating strains of lyophilized microscopic fungi of the genera Epidermophyton, Microsporum, Paecilomyces and Trichophyton have been maintained at 2-8 degrees C for 8-14 years. In 23 strains the number of viable particles reduced less than 10-fold during this period compared with immediately after lyophilization. The viability of other three investigated strains ranged from 3.4% to 7.1% in comparison with the original values.

Studies on growth, spore-forming ability and virulence of the vaccine strain TV-M-310 of the vaccine Bioveta against ringworm

We determined the intensity of growth, the ability to form spores and virulence in guinea pigs of the vaccine strain of the Czech live vaccine Bioveta. Comparative investigations were carried out with the vaccine strain of the Russian live vaccine LTF 130 and Trichophyton verrucosum field strains. Growth of the vaccine strains was faster than growth of the field strains on solid media and in broth. Later the vaccine strains formed many microconidia. In experimentally infected guinea pigs the virulence of the vaccine strain Bioveta was highly dependent on the infectious dose. At 10(1) CFU ml-1 (according to the number of CFUs in the Russian live vaccine) the vaccine strain Bioveta was nearly avirulent. Resuspended according to the manufacturer's instructions (at least 10(10) CFU ml-1) virulence of the vaccine strain Bioveta could be observed.

Adherence of arthroconidia and germlings of anthropophilic and zoophilic varieties of Trichophyton mentagrophytes to human corneocytes as an early event in the pathogenesis of dermatophytosis

The association (adherence) between human corneocytes and arthroconidia of Trichophyton mentagrophytes strains 121 and 126, and T. interdigitale strain 4 was studied in vitro. Adherence of arthroconidia to corneocytes from either the palm and sole occurred and increased with time up to 6 h, by which time germination of arthroconidia had started. Significant differences were seen between the T. mentagrophytes strains and T. interdigitale in their adherence to corneocytes from the palm. When adherence values for plantar corneocytes were compared, significant differences were found between T. mentagrophytes and T. interdigitale. Not all corneocytes from either site had adherent arthroconidia, although there was a time-dependent increase in the numbers of corneocytes with adherent fungal cells. By scanning and transmission electron microscopy it was seen that there was a loose association between arthroconidia and corneocytes with no apparent damage to the corneocyte membrane. Adherence of germlings of T. interdigitale to corneocytes from the palm appeared to be mediated by germling outer cell wall fibrils. Hyphal branches and secondary germlings were observed to enhance the attachment of the parent hypha to adjacent corneocytes.

Pathogenesis of hair infection and black dots in tinea capitis caused by Trichophyton violaceum: a histopathological study

The majority of tinea capitis in southern Taiwan occur in adult women and are caused by Trichophyton violaceum. We report the histopathological findings of a series of 10 cases of tinea capitis caused by T. violaceum, the largest such study to date. Our study provides new information regarding the process of hair infection, mechanism of black dot formation, and chronicity of infection caused by this fungus. The cuticle remains intact. The fungi enter the proximal cortex where the cuticle is immature. They then colonize the proximal keratinized cortex and generate septate hyphae which transform gradually into arthrospores as they are carried upwards by the growing hair. At the infundibular level, the hair cortex is almost completely replaced by spores and swells, impeding further exit of the growing hair and causing the already weakened hair to coil up inside the infundibulum, forming a black dot. In one patient who had infection for more than 20 years, there were changes suggestive of cyclic reinfection of the same follicles which might contribute to the chronicity of the infection.

The effect of dermatophyte species and density of infection on the pathology of ringworm

In this study we have measured the mean hyphal length as a function of the density of infection in skin surface biopsies from patients suffering from infection with different species of dermatophyte. The tissue response in the epidermis and dermis of these patients was evaluated for the degree of eczematization (epidermal thickening, spongiosis and dermal infiltrate) in periodic acid Schiff stained histological sections, employing visual analogue scales. There was no correlation between mean hyphal density and the degree of eczematization.