Genotype Analysis of the Variable Internal Repeat Region in the rRNA Gene ofTrichophyton tonsuransIsolated from Japanese Judo Practitioners

Molecular typing of a collection of Iranian clinical Trichophyton tonsurans isolates based on the non-transcribed spacer region of rDNA and antifungal susceptibility testing of the species

INTRODUCTION

Wrestling, considered the national sport of Iran, has gained immense popularity among Iranians. Wrestlers frequently encounter skin conditions, with dermatophyte fungal infections, particularly tinea gladiatorum (TG), being a common issue. TG, caused by the Trichophyton genus, has emerged as a major health concern for wrestlers and other contact sport athletes worldwide. This study aimed to assess the genotypic diversity and antifungal susceptibility of Trichophyton tonsurans isolates responsible for TG in Iranian wrestlers from Mazandaran province, northern Iran.

MATERIALS AND METHODS

A total of 60 clinical T. tonsurans isolates collected from various cities in Mazandaran, were included in the study. The isolates were identified through PCR-restriction fragment length polymorphism and sequencing methods. Genomic DNA was extracted from these isolates, and the non-transcribed spacer (NTS) region of ribosomal RNA (rRNA) was targeted for genotyping using newly designed primers. Haplotype analysis was performed to explore genetic diversity, and antifungal susceptibility to terbinafine (TRB) and itraconazole (ITC) was assessed.

RESULTS

The results revealed five distinct NTS types: NTS-I, NTS-II, NTS-III, NTS-IV and NTS-V, with NTS-IV being the most prevalent. The distribution of NTS types varied across different cities, suggesting potential transmission patterns among wrestlers. Antifungal susceptibility testing showed that all isolates were susceptible to TRB, while one isolate demonstrated resistance to ITC. Genotypic diversity was not correlated with antifungal susceptibility, emphasising the importance of monitoring susceptibility to ensure effective treatment. Haplotype analysis highlighted significant genetic diversity among the T. tonsurans isolates. This diversity may be attributed to factors such as human-to-human transmission, geographic location and lifestyle changes. The study's findings underscore the need for comprehensive genotypic analysis to understand the epidemiology and evolution of T. tonsurans infections in athletes.

CONCLUSION

In conclusion, this study provides valuable insights into the genotypic diversity and antifungal susceptibility of T. tonsurans isolates causing TG in Iranian wrestlers. The presence of multiple NTS types and varying susceptibility patterns highlights the complexity of T. tonsurans infections in this population. Further research is warranted to track the transmission routes and genetic evolution of T. tonsurans strains among wrestlers and develop effective control measures.

Clonal Outbreak of Trichophyton tonsurans Causing Tinea Capitis Among a Wrestling Team in Beijing, China

Trichophyton tonsurans mostly causes tinea capitis and tinea corporis and often associates with outbreaks among combat sports athletes. Here, we report an outbreak of tinea capitis caused by T. tonsurans among five juvenile athletes in a wrestling team in Beijing, China. Scrapings from the lesions of the five patients were performed by direct microscopic examination and fungal culture. The fungal pathogens were all identified as T. tonsurans by morphology and sequencing of the internal transcribed spacer (ITS) regions. Multilocus genotyping analysis was performed by sequencing of 13 gene loci. The sequences of these markers were identical among the five isolates, revealing a single genotype. Antifungal susceptibilities of terbinafine, itraconazole, fluconazole, ketoconazole, and amphotericin B against T. tonsurans was determined by broth microdilution method according to the Clinical and Laboratory Standards Institute M38-A3 document and these isolates were all susceptible to the common antifungal drugs treating tinea capitis.

Trichophyton tonsurans in Chile: genotyping in search of an origin

Trichophyton tonsurans is a cosmopolitan dermatophyte, highly prevalent in Africa, South America, and endemic in North America, where it is mostly related to cases of tinea capitis. Recently, it was also reported in Chile for the first time in two outbreaks occurred in Santiago. In the present study we sequenced the variable internal repeat (VIR) region of a Chilean isolate and compared its genotype with those of several global T. tonsurans isolates. The results showed that the Chilean isolate presented a new genotype which was strictly correlated with isolates from Europe, USA and Mexico.

Molecular strain typing of Trichophyton mentagrophytes (T. mentagrophytes var. interdigitale) using non-transcribed spacer region as a molecular marker

Background & objectives:

Dermatophytes are keratinophilic fungi that infect keratinized tissues of human and animal origin. Trichophyton mentagrophytes is considered to be a species complex composed of several strains, which include both anthropophiles and zoophiles. Accurate discrimination is critical for comprehensive understanding of the clinical and epidemiological implications of the genetic heterogeneity of this complex. Molecular strain typing renders an effective way to discriminate each strain. The objective of the study was to characterize T. mentagrophytes clinical isolates to sub-species level using molecular techniques and non-transcribed spacer (NTS) region as marker.

Methods:

Sixty four T. mentagrophytes clinical isolates were identified by phenotypic methods. These were subjected to polymerase chain reaction targeting three sub-repeat elements (SREs), TmiS0, TmiS1 and TmiS2 of the NTS region. Sequence analysis of internal transcribed spacer (ITS) region of different types was also done.

Results:

Strain-specific polymorphism was observed in all three loci. Totally, 13 different PCR types were obtained on combining all the three SREs loci. No variation was observed in the ITS region.

Interpretation & conclusions:

The study described the usefulness of molecular strain typing technique for the discrimination of the T. mentagrophytes isolates. This will help for the future explorations into the epidemiology of T. mentagrophytes and its complex.

Molecular Markers Useful for Intraspecies Subtyping and Strain Differentiation of Dermatophytes

Dermatophytosis is a very common skin disorder and the most frequent infection encountered by practicing dermatologists. The identification, pathogenicity, biology, and epidemiology of dermatophytes, the causative agents of dermatophytosis, are of interest for both dermatologists and medical mycologists. Recent advances in molecular methods have provided new techniques for identifying dermatophytes, including intraspecies variations. Intraspecies subtyping and strain differentiation have made possible the tracking of infections, the identification of common sources of infections, recurrence or reinfection after treatment, and analysis of strain virulence and drug resistance. This review describes molecular methods of intraspecies subtyping and strain differentiation, including analyses of mitochondrial DNA and non-transcribed spacer regions of ribosomal RNA genes, random amplification of polymorphic DNA, and microsatellite markers, along with their advantages and limitations.

Mating Type Gene (MAT) and Itraconazole Susceptibility of Trichophyton tonsurans Strains Isolated in Japan

Infection by Trichophyton tonsurans is an emerging fungal epidemic in Japan. Itraconazole (ITZ) and terbinafine have been used for the treatment of this infection for 15 years. However, patients with T. tonsurans infections have been shown to remain uncured or to become reinfected, suggesting that subclinical infection or polyphyletic strains and/or antifungal drug-resistant strains might be occurring in Japan. In this study, PCR analysis was performed to confirm the presence of the mating type locus MAT in genomic DNA from 60 Japanese clinical isolates of T. tonsurans, and to assess the previously postulated clonal origin of clinical isolates of this species. Antifungal susceptibility testing on isolates also was performed to confirm the absence of strains resistant to ITZ. PCR analysis proved that all 60 strains contained the MAT1-1 allele, while none contained the MAT1-2 allele. As determined by E-test, the mean MIC of ITZ in the 60 strains was 0.023 mg/L (range 0.002-0.125 mg/L). All strains of T. tonsurans isolated in Japan were clonal and were not resistant to ITZ. Therefore, dermatophytosis due to T. tonsurans is expected to respond to ITZ, since clinical isolates of T. tonsurans tested to date have been susceptible to this antifungal. This infection is proliferating as a subclinical infection in Japan.

Molecular epidemiology, phylogeny and evolution of dermatophytes

Dermatophytes are fungi that invade and propagate in the keratinized skin of mammals, including humans, often causing contagious infections. The species of medical concern belong to the genera Microsporum, Trichophyton, Epidermophyton (in their anamorphic state) and Arthroderma (in their telomorphic state), which were traditionally identified based on their morphology and biochemical characters. Nonetheless, limitations linked to the differentiation of closely related agents at species and strains level have been recently overcome by molecular studies. Indeed, an accurate identification of dermatophytes is pivotal for the establishment of effective control and prevention programs as well as for determining the most appropriate and effective antifungal therapies to be applied. This article reviews the DNA techniques and the molecular markers used to identify and to characterize dermatophyte species, as well as aspects of their phylogeny and evolution. The applications of typing molecular strain to both basic and applied research (e.g., taxonomy, ecology, typing of infection, antifungal susceptibility) have also been discussed.

Infectious disease outbreaks in competitive sports, 2005-2010

CONTEXT

Old, evolving, and new infectious agents continually threaten the participation of competitors in sports.

OBJECTIVE

To provide an update of the medical literature on infectious disease outbreaks in sport for the last 5 years (May 2005-November 2010).

MAIN OUTCOME MEASURE(S)

A total of 21 outbreaks or clusters were identified.

RESULTS

Methicillin-resistant Staphylococcus aureus (n = 7, 33%; mainly community acquired) and tinea (trichophytosis: n = 6, 29%) were the most common pathogens responsible for outbreaks. Skin and soft tissue was the most common site of infection (n = 15, 71%).

CONCLUSIONS

The majority of outbreaks reported occurred in close-contact sports, mainly combat sports (ie, wrestling, judo) and American football. Twelve outbreaks (57%) involved high school or collegiate competitors. Common community outbreak pathogens, such as influenza virus and norovirus, have received little attention.

Molecular typing of Trichophyton mentagrophytes var. interdigitale isolated in a university hospital in Japan based on the non-transcribed spacer region of the ribosomal RNA gene

Detecting intraspecies polymorphisms in fungi causing dermatophytoses is important in elucidating routes of infection and determining whether Tinea recurrence is caused by exacerbation or re-infection. In fungi, the non-transcribed spacer region (NTS) of the ribosomal RNA gene shows the greatest accumulation of base sequence mutations. We therefore assessed NTS sequences in 64 clinical isolates of Trichophyton mentagrophytes var. interdigitale, the second most common species of dermatophytes in Japan. These isolates were among the clinical isolates of dermatophytes in the Department of Dermatology, Kanazawa Medical University Hospital in 2006 and were obtained by morphological and molecular biological identification methods. DNA was extracted from each isolate, as well as from one isolate maintained in our department, to detect length polymorphisms at each of three variable loci, TmiS0, TmiS1 and TmiS2, of the NTS for subtyping. We observed seven patterns for TmiS0, six patterns for TmiS1 and three patterns for TmiS2. The combinations of these patterns enabled us to classify the 65 isolates into 15 types. The most prevalent, constituted 46% (30/65) of all isolates. Eleven types were new combinations, whereas the other four were previously described. These results suggest that this method may be used to determine the molecular epidemiology of T. mentagrophytes var. interdigitale in Japan, because it generated results rapidly and in a sensitive manner.

[Screening examination of Trichophyton tonsurans among Judo practitioners at the All Japan Inter High School Championships, Saga 2007]

This paper presents the results of an examination for Trichophyton tonsurans(T. tonsurans)performed by the hairbrush (HB; 90 bristles)method at the All Japan Inter High School Championships, Saga 2007. Samples were taken from 487 Judo practitioners (265 males and 222 females) out of a total of 951. The areas with the highest positive rates were: Kyushu 21%(15 participants out of 73 sampled), Tohoku 17% (13 out of 77), Kinki 16% (14 out of 89), and Chubu 13% (12 out of 89). Four participants from Kyushu, four from Tohoku, two from Kinki, and two from Chubu were strongly positive carriers, their samples developing more than 30 colonies per dish. This finding is in concordance with the high HB-positive rates in these areas. The results of a questionnaire distributed during sampling showed that 90% of the examinees had heard of T. tonsurans infection, 11% had been sampled by the HB method previously, and 37% declined to receive the results of the medical examination. The low percentage of participants who had experienced a HB sampling before could be explained by the insufficient penetration of this test among dermatologists, as well as by the fact that team trainers are reluctant to expose their athletes to sampling. Although trainers' education concerning T. tonsurans is also an important factor, we strongly recommend that dermatologists take the initiative to perform medical examinations such as HB sampling in schools or at other public organizations. As for the reason why so many practitioners refused to be informed about the diagnosis, many of them mentioned being afraid that it might be overheard by trainers or fellow practitioners. It can be easily inferred that this type of concern leads Judo practitioners to avoid participation in sampling. Therefore, we concluded that substantial care to protect personal information is essential when communicating the results of the examination.

Differentiation of Trichophyton rubrum clinical isolates from Japanese and Chinese patients by randomly amplified polymorphic DNA and DNA sequence analysis of the non-transcribed spacer region of the rRNA gene

BACKGROUND

Trichophyton rubrum is the most common pathogen causing dermatophytosis worldwide. Recent genetic investigations showed that the microorganism originated in Africa and then spread to Europe and North America via Asia.

OBJECTS

We investigated the intraspecific diversity of T. rubrum isolated from two closely located Asian countries, Japan and China.

METHODS

A total of 150 clinical isolates of T. rubrum obtained from Japanese and Chinese patients were analyzed by randomly amplified polymorphic DNA (RAPD) and DNA sequence analysis of the non-transcribed spacer (NTS) region in the rRNA gene.

RESULTS

RAPD analysis divided the 150 strains into two major clusters, A and B. Of the Japanese isolates, 30% belonged to cluster A and 70% belonged to cluster B, whereas 91% of the Chinese isolates were in cluster A. The NTS region of the rRNA gene was divided into four major groups (I-IV) based on DNA sequencing. The majority of Japanese isolates were type IV (51%), and the majority of Chinese isolates were type III (75%).

CONCLUSIONS

These results suggest that although Japan and China are neighboring countries, the origins of T. rubrum isolates from these countries may not be identical. These findings provide information useful for tracing the global transmission routes of T. rubrum.

Multilocus genotyping identifies infections by multiple strains of Trichophyton tonsurans

Acquisition of multiple genetic strains of a single dermatophyte species should not be unexpected in areas of high endemicity, and yet multistrain infections are infrequently reported. This communication details mixed Trichophyton tonsurans infections and highlights the need to confirm the presence of multiple strains in a clinical single isolate by use of a multilocus approach.