Molecular identification of Trichophyton rubrum isolate from a dog by chitin synthase 1 (CHS1) gene analysis

A nonsporulating isolate from a dog with dermatophytosis was identified as Trichophyton rubrum by molecular analysis. The nucleotide sequence analysis of the chitin synthase 1 (CHS1) gene from the isolate indicated more than 99% sequence similarity with other human and canine isolates of T rubrum. The molecular typing suggested that isolates of T. rubrum from human and canine sources were genetically identical.

Case Report. Widespread tinea corporis due to Trichophyton rubrum

We report the case of a 36-year-old man who presented large erythematous plaques involving the trunk, face and extremities, since one month. Some of these lesions had a psoriasis-like aspect, with abundant superficial scaling. Direct microscopic examination of scales removed from the plaques revealed numerous hyphae. Cultural examination lead to the identification of Trichophyton rubrum species. Our case of tinea corporis presented some peculiarities related both to the extension of the lesions and their clinical aspects.

First isolation of Trichophyton raubitschekii (syn. T. rubrum) in Europe

Trichophyton raubitschekii is a rare dermatophyte which belongs to the Trichophyton rubrum species complex. Since 1981, only a few cases of dermatophytosis due to this anthropophilic causative agent were published. In this paper the authors report the first cases of Tinea corporis caused by Trichophyton raubitschekii (syn. T. rubrum) in Europe. The patients, one immigrant from Ghana and three from Cameroon, had typical lesions of tinea corporis. Four strains were isolated and characterized by conventional and molecular methods. On morphological and physiological grounds the isolates were identified as T. raubitschekii by the following phenotypical features: (1) velvety colony texture; (2) brown pigment; (3) abundant macroconidia and (4) positive urease activity. Molecular diagnostics were performed by single strand conformation polymorphism (SSCP) and sequence analysis of the ATPase9 intron of the mitochondrial (mt) DNA and the internal transcribed spacer (ITS) region of the rDNA, respectively. The ITS sequences and SSCP patterns of the ATPase9 intron were found to be identical among the four strains and also when compared to reference strains of T. rubrum. As shown in the present paper, T. raubitschekii is genetically identical to T. rubrum but differs in some phenotypical characteristics. Since misidentification with other dark-coloured dermatophyte variants is possible, medical mycologists should bear in mind the special morphological characteristics of T. raubitschekii (syn. T. rubrum) for future identifications.

Identification and subtyping of Trichophyton mentagrophytes by random amplified polymorphic DNA

Trichophyton mentagrophytes is one of the most common pathogens for human and animal dermatophytoses and known as a complex species with variable morphology, and ecologic and genetic backgrounds. We performed random amplified polymorphic DNA (RAPD) analysis on 43 human and 18 animal isolates of T. mentagrophytes along with other 10 anamorphic species of dermatophytes and three teleomorphic species of T. mentagrophytes. Using RAPD analysis with primer 5'-ATGGATC(G,C)(G,C)C-3' (ATGS), all T. mentagrophytes strains produced identical band patterns with those of Arthroderma vanbreuseghemii, one of the teleomorphs of T. mentagrophytes, regardless of their phenotypes. Therefore, T. mentagrophytes could be identified by RAPD analysis with primer ATGS. Using RAPD analysis with primer 5'-ATGGATCGGC-3' (ATG) on T. mentagrophytes, human isolates yielded two distinct subgroups related by their colony morphologies at the time of primary isolation from patients. Three morphologic types--cottony, powdery and persicolor--revealed identical bands whereas the granular type lacked one minor band (0.74 kbp). Animal isolates of T. mentagrophytes produced five band patterns and some of them were identical with those of human isolates. With primer 5'-GAAGGCTCCC-3' (OPAO-15), animal isolates of T. mentagrophytes showed diverse band patterns in contrast to the uniform band pattern of human isolates. These results suggest that RAPD analysis may be a useful tool to identify and subtype T. mentagrophytes complex.

Variation in restriction fragment length polymorphisms among serial isolates from patients with Trichophyton rubrum infection

Molecular genotyping of strains of Trichophyton rubrum and T. mentagrophytes from patients with onychomycosis of the toes was performed to ascertain whether the fungal genotype changes over the course of time as sequential samples were obtained from patients receiving antifungal therapy and during follow-up. Sixty-six serial strains of T. rubrum and 11 strains of T. mentagrophytes were obtained from 20 patients (16 patients with T. rubrum, 4 with T. mentagrophytes) who were treated with oral antifungal therapy and observed over periods of up to 36 months. These strains were screened for genetic variation by hybridization of EcoRI-digested genomic DNAs with a probe amplified from the small-subunit (18S) ribosomal DNA and adjacent internal transcribed spacer regions. A total of five restriction fragment length polymorphism (RFLP) types were observed among 66 strains of T. rubrum. Two major RFLP types, differentiated by one band shift, represented 68% of the samples. None of the patients had a unique genotype. More than one RFLP type was often observed from a single patient (same nail) over a period of 1, 2, or 3 years, even in cases that did not appear cured at any time. Samples taken from different nails of the same patient had either the same or a different genotype. The genotypic variation did not correspond to any detectable phenotypic variation. Furthermore, no correlation was observed between the efficacy of the treatment administered and the genotype observed. While the DNA region studied distinguished among T. rubrum, T. mentagrophytes, and T. tonsurans, intraspecific RFLP variation was observed for T. rubrum and T. mentagrophytes strains. While independent multiple infection and coinhabitation of multiple strains may explain the presence of different genotypes in a nail, microevolutionary events such as rapid substrain shuffling, as seen in studies of repetitive regions in Candida species, may also produce the same result. The recovery of multiple strains during the course of sequential sampling of uncured patients further suggests that the typing system is not able to distinguish between relapse or reinfection, ongoing infection, and de novo infection.

Application of PCR to distinguish common species of dermatophytes

This report describes the application of PCR fingerprinting for the identification of species and varieties of common dermatophytes and related fungi utilizing as a single primer the simple repetitive oligonucleotide (GACA)(4). The primer was able to amplify all the strains, producing species-specific profiles for Microsporum canis, Microsporum gypseum, Trichophyton rubrum, Trichophyton ajelloi, and Epidermophyton floccosum. Intraspecific variability was not observed for these species. Instead, three different profiles were observed in the Trichophyton mentagrophytes group.

The aetiological agents of tinea capitis in Zaragoza (Spain)

Between 1977 and 1997, 190 cases of tinea capitis were observed. The age groups most commonly infected were 1-10 years old. The following dermatophytes were isolated: Microsporum canis (119), Trichophyton mentagrophytes (57), Trichophyton tonsurans (seven), Trichophyton verrucosum (three), Trichophyton violaceum (one), Trichophyton schoenleinii (one), Trichophyton soudanense (one) and Microsporum audouinii (one).

Comparative efficacies of commonly used disinfectants and antifungal pharmaceutical spray preparations against dermatophytic fungi

Arthroconidia from five fungal strains belonging to three Trichophyton species, Trichophyton mentagrophytes, T. raubitschekii and T. tonsurans, were tested against commercial chemical disinfectants and pharmaceutical antifungal agents. The chemical disinfectants included chlorine, phenol, sodium dodecyl sulphate and several quaternary ammonium salts, while the two pharmaceutical preparations contained bifonazole and terbinafine as active agents. Arthroconidia were exposed to the antifungal agent either in a suspension solution for a given period of time and assayed for kill rate, or on a sprayed agar plate and monitored for surviving colonies over a period of 14 days. Chlorine (1%) and terbinafine (0.01%) were found to be high level disinfectants bringing about a rapid inactivation of conidia in all five strains. Phenol was equally effective against T. raubitschekii and T. tonsurans; however, T. mentagrophytes cells were able to survive for up to 1 h in 5% phenol. Quaternary ammonium compounds were less rapid in their action against dermatophytes and were needed at a level of about 0.5% to be completely fungicidal. Three commercial spray formulations with a range of 0.1 to 0.3% quaternary ammonium salts were fungistatic against T. mentagrophytes strains. Bifonazole (1%) was also fungistatic in its action against T. mentagrophytes. Sodium dodecyl sulphate (0.5%) was largely ineffective against Trichophyton arthroconidia.

Favus due to Trichophyton mentagrophytes var. quinckeanum

We report a case of favus affecting the temporal region of the scalp in a 22-month-old boy. Mycological study of hairs and crusts identified Trichophyton mentagrophytes var. quinckeanum (T. quinckeanum), the causative agent of mouse favus. Treatment with oral griseofulvin led to healing.

[The effect of Medicago spp. on growth of Trichophyton mentagrophytes in microculture]

The study aimed at assessing effect of dried root and aerial parts of Medicago spp. on growth of Trichophryton mentagrophytes. Fungus strains were inoculated onto microcultures with Sabouraud agar supplemented each with 1 g of dried and pulverised roots or aerial parts of 3 species: Medicago arabica, M. sativa, and M. murex. The strongest inhibitory effect on T. mentagrophytes growth was that of aerial parts of M. arabica (median diameter 6 mm compared to 13 mm of control), followed by root of M. arabica (10 mm) and root of M. murex (10.5 mm)--in all cases p < 0.001. Slight inhibitory effect was also found in the case of aerial parts of M. murex (median diameter 12 mm, p = 0.03). In contrast, M. sativa has shown stimulating effect on growth of T. mentagrophytes (15 mm for root and 16.5 mm for aerial part, p<0.001).

Strain identification of Trichophyton rubrum by specific amplification of subrepeat elements in the ribosomal DNA nontranscribed spacer

Trichophyton rubrum is the commonest cause of dermatophytosis of skin and nail tissue. Molecular characterization of the T. rubrum ribosomal DNA nontranscribed-spacer region revealed two novel tandemly repetitive subelements (TRSs): TRS-1, containing a 27-bp palindromic sequence, and TRS-2. Specific amplification of TRS-1 produced strain-characteristic banding patterns (PCR types), with 21 TRS-1 PCR types recognized from 101 clinical isolates. Four simple patterns representing 1 to 4 copies of TRS-1 accounted for 75 (75%) of all 101 strains, whereas more complex patterns were observed for 21 (20%) of the 101 isolates. The copy number of TRS-2 was 0 to 3 repeats per cistron, with a majority of isolates having two copies of this element. Eleven isolates were polymorphic for TRS-2, and in combination, 23 separate PCR types were recognized by amplification of both TRS-1 and TRS-2. The PCR patterns from both elements were stable and reproducible. Elements with homology to TRS-1 were present in three phylogenetically related species, Trichophyton violaceum, Trichophyton gourvilii, and Trichophyton soudanense, but these elements were not identified in other dermatophyte taxa. There was no clear correlation of PCR type with specimen (skin or nail tissue), but certain PCR types appeared to show a bias in geographic distribution. This new method of typing T. rubrum will enable important questions about pathogenesis and epidemiology of this fungus to be addressed.

An epidemic of tinea corporis caused by Trichophyton tonsurans among children (wrestlers) in Germany

An outbreak of tinea corporis due to Trichophyton tonsurans among 46 children (aged 7-17 years) was investigated. Most of them were wrestlers. Thirty-one strains were identified by conventional methods, but proved to be problematic in 15 isolates due to colony variation and reduced sporulation. They were identified as Trichophyton tonsurans by the use of molecular methods, for example, sequence comparison of the ribosomal internal transcribed spacer (ITS) region and polymerase chain reaction fingerprinting. No DNA polymorphisms were detected with any of the techniques used, suggesting clonal reproduction of the populations of the species and providing evidence for spatial and temporal stability of the lineage.

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.

Hazardous hedgehogs

The African pygmy hedgehog has recently become a fashionable exotic pet in the United States, particularly in the South. As illustrated by the three cases reported, this mammalian insectivore can be a carrier of fungi that cause human dermatomycoses. The African pygmy hedgehog has also been associated with contact urticaria and human salmonellosis.

Prevalence and risk factors of tinea unguium and tinea pedis in the general population in Spain

This study prospectively evaluated the prevalence and risk factors of tinea unguium and tinea pedis in the general adult population in Madrid, Spain. One thousand subjects were clinically examined, and samples of nails and scales from the interdigital spaces of the feet were taken from those patients presenting with signs or symptoms of onychomycosis and/or tinea pedis, respectively. In addition, a sample from the fourth interdigital space of both feet was collected from all individuals with a piece of sterilized wool carpet. Tinea unguium was defined as a positive direct examination with potassium hydroxide and culture of the etiological agent from subjects with clinically abnormal nails. Patients with positive dermatophyte cultures of foot specimens were considered to have tinea pedis. The prevalence of tinea unguium was 2.8% (4.0% for men and 1.7% for women), and the prevalence of tinea pedis was 2.9% (4.2% for men and 1.7% for women). The etiological agents of tinea unguium were identified as Trichopyton rubrum (82.1%), followed by Trichopyton mentagrophytes var. interdigitale (14.3%) and Trichopyton tonsurans (3.5%). Trichophyton rubrum (44.8%) and Trichophyton mentagrophytes (44.8%), followed by Epidermophyton floccosum (7%) and T. tonsurans (3.4%), were the organisms isolated from patients with tinea pedis. The percentage of subjects who suffered simultaneously from both diseases was 1.1% (1.7% for men and 0.6% for women). In a multivariate logistic regression analysis, age (relative risk [RR], 1.03) and gender (RR, 2.50) were independent risk factors for tinea unguium, while only gender (RR, 2.65) was predictive for the occurrence of tinea pedis. In both analyses, the presence of one of the two conditions was associated with a higher risk for the appearance of the other disease (RR, >25).

Molecular confirmation of a Trichophyton violaceum isolate from human black-dot ringworm

A clinical isolate from a black-dot ringworm lesion of a 28-year-old female Japanese was investigated by morphological and biochemical analyses as well as molecular analyses. The isolate grew well on thiamine enriched agar and did not produce violet pigment, macro-conidia or micro-conidia on Sabouraud's dextrose agar. Approximately 620-bp genomic DNA fragments of the CHS1 gene were amplified from Trichophyton mentagrophytes, T. rubrum, T. tonsurans and T. violaceum by polymerase chain reaction (PCR) and sequenced. The chitin synthase 1 (CHS1) nucleotide sequences of the clinical isolate showed more than 97% similarity to that of T. violaceum and less than 96% similarity to that of T. mentagrophytes, T. rubrum and T. tonsurans. The phylogenetic analysis of their sequences revealed that the clinical isolate was genetically close to T. violaceum and distinct from T. mentagrophytes, T. rubrum and T. tonsurans. Therefore, the isolate was confirmed as T. violaceum by mycological examination and molecular analyses.

Human cases of cattle ringworm due to Trichophyton verrucosum in Victoria, Australia

Between 1962 and 1994, 32 isolates of Trichophyton verrucosum from cases of tinea corporis, tinea faciei and tinea capitis were referred to the Mycology Reference Laboratory of the Microbiological Diagnostic Unit at The University of Melbourne, Victoria, Australia. Patients had presented at clinics in metropolitan Melbourne and country towns in the State of Victoria, Australia. They included dairy and cattle farmers, a slaughterman who worked in an abattoir, a veterinary tutor and children who lived on farms. Many patients lived in one of the three dairy farming areas of Victoria. A few lived in the outer suburbs of Melbourne. One cattle farmer came from south-east New South Wales. Specimens were not received for examination from animal contacts of the patients. The only patient from overseas was a boy from Lebanon. The literature recording human infections due to T. verrucosum in Australia is reviewed.

Diversity among wild type and vaccination strains of Trichophyton verrucosum investigated using random amplified polymorphic DNA analysis

We initially tested 20 primers for their ability to amplify genomic DNA of Trichophyton verrucosum using RAPD. Six of these were selected for further study aimed at discrimination of wild type and vaccination strains of T. verrucosum. The results indicate that RAPD successfully distinguished all strains included in the study. In addition, results of corrected cluster analysis were consistent with the fact that the avirulent vaccination strains (T. verrucosum TV-M9 and T. verrucosum TV-M-130) were prepared by ultraviolet (UV) light induced mutagenesis of the standard wild type strain T. verrucosum Strádznice. No marker for a/virulence was detected. These outcomes suggest new possibilities for epidemiological analyses, for discrimination among different vaccination strains and studies of fungal population in vaccinated/infected hosts.

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.

Epidemiology of dermatomycoses of humans in central Poland. Part IV. Onychomycosis due to dermatophytes

The total number of dermatophytoses (7393) included 1567 (21.2%) cases of onychomycosis. Etiological factors in descending order were: Trichophyton rubrum (58.8%), Trichophyton mentagrophytes var. granulosum (26.2%), T. mentagrophytes var. quinckeanum, T. mentagrophytes var. interdigitale (5.1%), Trichophyton tonsurans (4.1%), Trichophyton violaceum (1.5%), Trichophyton spec. (1.1%). An increase in the incidence was noted between 1994 and 1996. At present, onychomycosis is third by incidence among all clinical forms of dermatophyte infections of skin and skin appendages in the Lódź region.

Epidemiology of dermatomycoses of humans in central Poland. Part V. Tinea corporis

The total number of dermatophytoses (7393) included 2204 (29.8%) cases of tinea glabrosa. Etiological factors in descending order were: Microsporum canis (23.5%), Trichophyton mentagrophytes var. granulosum (21.6%), Trichophyton rubrum (17.8%), Trichophyton tonsurans (10.4%), Epidermophyton floccosum (7.7%), T. mentagrophytes var. quinckeanum (6.0%), Microsporum gypseum (5.3%), Trichophyton violaceum (3.7%), T. mentagrophytes var. interdigitale (2.3%), Microsporum equinum (0.7%), Trichophyton verrucosum (0.4%), Trichophyton spec. (0.4%), Microsporum cookei (0.14%). At present tinea glabrosa is dominant among all clinical forms of dermatophyte infections of skin and skin appendages in the Lódź region.

Differences among chitin synthase I gene sequences in Trichophyton rubrum and T. violaceum

Nucleotide sequences of chitin synthase 1 (CHS1) gene were analysed for the phylogenetic relation between Trichophyton violaceum and T. rubrum, including two isolates of T. raubitschekii and one isolate of T. rubrum var. nigricans. About 620-bp genomic DNA fragments of the CHS1 gene were amplified from these dermatophytes by polymerase chain reaction (PCR) and sequenced. The CHS1 nucleotide sequences of these dermatophytes showed more than 95% similarity between the species. The phylogenetic analysis of their sequences revealed that T. rubrum was genetically distinct from T. violaceum. The specific restriction endonuclease site for HinfI was present in the CHS1 gene sequence of T. rubrum but not in that of T. violaceum. A molecular analysis of CHS1 genes will provide useful information for the identification of these Trichophyton species and the understanding of their evolution.