Changes in frequency of agents of tinea capitis in school children from Western China suggest slow migration rates in dermatophytes

Detection of emerging genotypes in Trichophyton mentagrophytes species complex: A proposal for handling biodiversity in dermatophytes

A resistant and hypervirulent dermatophyte from India has been described as a taxonomic novelty, Trichophyton indotineae, a species of the Trichophyton mentagrophytes complex. Rapid detection and correct identification of closely similar dermatophytes with different predilections are essential for efficient clinical management. We evaluated the efficacy of rapid diagnostic methods clinical and environmental strains in the T. mentagrophytes complex. The methods included Real-time-PCR, DermaGenius, LAMP, and MALDI-ToF MS, using rDNA ITS sequences as taxonomic standard. The results show that only MALDI-ToF MS can distinguish 96.97% T. indotineae from other closely related species. The complex comprises numerous clones which may differ in anonymous markers but with similar evolutionary behavior. Therefore, we recommend to distinguish species only when they show an appreciable degree of adaptation and thus are clinically significant. The distinction of remaining clonal diversity is an epidemiological query and can be solved by haplotype numbering.

Tinea capitis in children: A single-institution retrospective review from 2011 to 2019

Tinea capitis remains a common public health problem worldwide, especially in developing countries.

OBJECTIVES

To investigate the changes of the predominant dermatophytes of tinea capitis in children in Hangzhou in recent 9 years.

METHODS

The age, gender and pathogen spectrum of 650 children with tinea capitis at the Department of Dermatology, Affiliated Third People's Hospital of Hangzhou, Anhui Medical University from 2011 to 2019 were analysed, and the distribution of pathogens from 1998 to 2000 was compared.

RESULTS

Among the 650 cases, 340 cases (48.2%) were males and 310 cases (51.8%) were females. The main population infected with tinea capitis was children aged 0-10 years (620 cases, 95.4%). From 2011 to 2019, the predominant dermatophyte was changed from Trichophyton violaceum (2011) to Trichophyton mentagrophytes complex (2012-2015) and later to Microsporum canis (2016-2019). In the past 9 years, M. canis (250 cases, 38.5%) was the most common dermatophyte and followed by T mentagrophytes complex (209 cases, 32.2%). The dermatophyte spectrum was statistically different between the years 2011 and 2019 (Chi square: χ²  = 69.75, P < .05), and the differences in anthropophilic and zoophilic pathogens between 1989-2000 and 2011-2019 were statistically significant (χ²  = 24.4, P < .05).

CONCLUSIONS

Research showed that children diagnosed with tinea capitis were mainly 0-10 years old. With age, the percentage of anthropophilic dermatophytes gradually increased, while the percentage of zoophilic dermatophytes decreased. M. canis was the predominant dermatophyte of tinea capitis in children, followed by T. mentagrophytes complex. The dermatophytes have shifted from anthropophilic to zoophilic dermatophytes in the past two decades.

Major challenges and perspectives in the diagnostics and treatment of dermatophyte infections

Dermatophytes are the aetiological factors of a majority of superficial fungal infections. What distinguishes them from other pathogenic filamentous fungi is their unique ability to degrade keratin. The remarkable ability of this group of fungi to survive in different ecosystems results from their morphological and ecological diversity as well as high adaptability to changing environmental conditions. Paradoxically, despite the progress in medicine, the prevalence of dermatophyte infections is increasing from year to year. At the beginning of the third millennium, practical diagnostic and therapeutic options are still very limited. This review focuses on understanding the major problems in this aspect of dermatophyte infections and indicates future strategies and perspectives for novel approaches to identification and drugs for elimination of dermatophytes. Particular importance is placed on development of a strategy for a diagnostic pathway and implementation of rapid and reliable diagnostics methods designed by international teams. Furthermore, among compounds that currently arouse great interest, representatives of terpenoids, alkaloids, saponins, flavonoids and essential oils deserve attention. Many of these compounds are undergoing clinical trials as potential antifungal agents, and future research should focus on attempts at determination of the applicability of tested substances. Finally, the advantages and disadvantages in implementation of new diagnostic paths and medicinal substances for routine use are indicated.

Molecular epidemiology and in vitro antifungal susceptibility of Trichophyton schoenleinii, agent of tinea capitis favosa

Trichophyton schoenleinii is an anthropophilic dermatophyte usually causing tinea favosa. Only few studies have provided data on molecular epidemiology and antifungal profiles of this fungus due to its limited prevalence after 1950s. Forty-nine strains from Asia (n = 27), Africa (n = 10), Europe (n = 10) and from unknown regions (n = 2) were analysed with amplified fragment length polymorphism fingerprinting (AFLP) to reveal intraspecific genetic diversity in this dataset. Amplified fragment length polymorphism fingerprinting genotyping revealed five clusters which did not correspond to geographic origins or clinical characteristics. Additionally, in vitro antifungal susceptibility to seven antifungals was provided for all strains. Terbinafine, ketoconazole, miconazole and itraconazole proved to be the most effective drugs, followed by griseofulvin. No correlation between genotypes and differences in antifungal susceptibility was observed. It is concluded that the AFLP groups are lineages within a single species.

Host- and pathogen-dependent susceptibility and predisposition to dermatophytosis

Dermatophytes are a highly specialized group of keratinophilic and keratinolytic filamentous fungi causing a ringworm disease called dermatophytosis or superficial mycoses. Although dermatophyte infections do not threaten the host's life, they lower its quality in humans by causing discomfort related to cosmetic problems and through their epidemiological significance, whereas in farm animals they are responsible for economic losses and constitute a source of the spread of spores. Evidence from countless observational studies that have been conducted over the last 90 years indicates that dermatophytes infect humans of every age, race, gender and socioeconomic status with strikingly high rates, as well as both farmed and wild animals in various health conditions and with various epidemiological statuses. However, the prevalence of superficial fungal infections is highly variable, since it depends on several parameters associated with the infected individual and the dermatophyte, their mutual interactions, and epidemiological and geographical factors. The curious disparity in dermatophyte infection patterns has prompted many investigators to search for a link between the host, the host's predispositions and susceptibility to the disease, and the dermatophyte species and virulence. Thus, the question arises as to whether, in addition to the generally recognized factors predisposing hosts to diseases, there are some other predispositions to dermatophyte infections in a species-specific host. In this review, we describe recent findings about the mechanism of dermatophyte infections, focusing on the adaptation of the fungi to the host and conditions predisposing each side to the disease.

Extensive tinea capitis and corporis in a child caused by Trichophyton verrucosum

A 3-year-old boy presented with multiple lesions of tinea corporis with dermatophytids, and subsequent inflammatory lesions with alopecia on the scalp. At the beginning, topical clobetasone butyrate was prescribed. The infection was diagnosed as dermatophytosis on the basis of positive direct microscopy and fungal culture. The etiological agent was isolated from all sampled sites and identified as Trichophyton verrucosum. Clonal nature of the infection was confirmed by random amplified polymorphic DNA (RAPD) analysis. The child lived in close vicinity of cattle. He was successfully treated with itraconazole.

In Vitro Antifungal Susceptibility Profiles of 12 Antifungal Drugs against 55 Trichophyton schoenleinii Isolates from Tinea Capitis Favosa Patients in Iran, Turkey, and China

Trichophyton schoenleinii is an anthropophilic dermatophyte mainly causing tinea favosa of the scalp in certain regions of the world, especially Africa and Asia. We investigated the in vitro susceptibilities of 55 T. schoenleinii isolates collected over the last 30 years from Iran, Turkey, and China to 12 antifungals using the CLSI broth microdilution method. Our results revealed that terbinafine and ketoconazole were the most potent antifungal agents among those tested, independently of the geographic regions where strains were isolated.

Tinea faciei on the right eyebrow caused by Trichophyton interdigitale

Tinea faciei is a relatively uncommon dermatophyte infection entailing atypical clinical symptoms, usually misdiagnosed and treated with corticosteroids. The authors describe a case of tinea faciei on the right eyebrow caused by Trichophyton interdigitale. The patient was an 18-year-old girl, who had an inflammatory plaque with a scaly, pustular surface on the right eyebrow and upper eyelid, which had persisted for over 1 month. She was once misdiagnosed as having eczema and was treated using corticosteroid cream. A diagnosis of tinea faciei was made based on direct microscopy and culture. The sequencing of the nuclear ribosomal ITS region and β-tubulin gene of the isolate established its T. interdigitale lineage. The patient was cured by treatment with systemic terbinafine in combination with topical application of 1% naftifine-0.25% ketaconazole cream for 2 weeks.

Evaluation of two molecular techniques for rapid detection of the main dermatophytic agents of tinea capitis

BACKGROUND

Tinea capitis is very common in Western China, with the most widespread aetiological agent being Trichophyton violaceum, while Microsporum canis is prevalent in the remainder of China. Conventional diagnostics and internal transcribed spacer (ITS) sequencing analyses have proven relatively limited due to the close phylogenetic relationship of anthropophilic dermatophytes. Therefore, alternative molecular tools with sufficient specificity, reproducibility and sensitivity are necessary.

OBJECTIVES

To evaluate two molecular techniques [multiplex ligation-dependent probe amplification (MLPA) and rolling circle amplification (RCA)] for rapid detection of the aetiological agents of tinea capitis, T. violaceum and M. canis.

METHODS

Probes of RCA and MLPA were designed with target sequences in the rDNA ITS gene region. Strains tested consist of 31 T. violaceum, 22 M. canis and 24 reference strains of species that are taxonomically close to the target species.

RESULTS

The specificity and reproducibility of RCA and MLPA in detection of T. violaceum and M. canis were both 100% in both species. Sensitivity testing showed that RCA was positive at concentrations down to 1·68 × 10(6) copies of DNA in the TvioRCA probe, and 2·7 × 10(8) copies of DNA in McRCA. MLPA yielded positive results at concentrations of DNA down to 1·68 × 10(1) copies in the TvioMLPA probe and 2·7 × 10(2) in McMLPA.

CONCLUSIONS

The two techniques were sufficiently specific and sensitive for discriminating the target DNA of T. violaceum and M. canis from that of closely related dermatophytes. RCA and MLPA are advantageous in their reliability and ease of operation compared with standard polymerase chain reaction and conventional methods.

Epidemiological changes in tinea capitis over the sixty years of economic growth in China

BACKGROUND

Tinea capitis is a fungal infection of the scalp occurring commonly in children. Historical data indicate that clinical manifestations and the spectrum of etiologic agents vary greatly with geography, as well as socioeconomic affected populations.

OBJECTIVE

To study the possible connection between socioeconomic status, the disease patterns and the variability of etiological agents.

METHODS

We reviewed tinea capitis in China through literature since 1956. The disease pattern was correlated with economic and public health management protocols. Historical data on fungal identification were mostly obtained by morphology. The accuracy of these historical results was further confirmed by use of both morphological and ITS identification on a control set of 90 isolates collected recently from local hospital.

RESULTS

Full agreement of the two identification methods implies that data from the literature were sufficiently reliable to allow comparison across reported cases. In sum, 88 papers involving 25 administrative provinces and municipalities with 38,962 clinical strains met the inclusion criteria of this review. Zoophilic species Microsporum canis is the most prevalent agent within large, modernized cities in China today accounting for over 80% of infections. In contrast, anthropophilic dermatophytes, particularly Trichophyton violaceum, are geographically endemic only in some southeastern and northwestern regions.

CONCLUSION

Economic development and urbanization of cities favor a shift of etiological agents from anthroponoses to zoonoses in contemporary China. Pets are becoming the most likely sources of infection in modern lifestyles, replacing the earlier human-to-human transmission mode. However, the latter transmission mode is still prevalent in less developed areas lacking adequate social and public health facilities.

In vitro antifungal susceptibility of Trichophyton violaceum isolated from tinea capitis patients

OBJECTIVES

Trichophyton violaceum is an anthropophilic dermatophyte that is endemic to parts of Africa and Asia and is sporadic in Europe. T. violaceum mainly causes tinea capitis in both children and adolescents. Although the infections caused by T. violaceum are of considerable medical importance, its antifungal susceptibility profile remains poorly examined.

METHODS

In this study, we tested the in vitro antifungal susceptibility of a set of clinical T. violaceum isolates obtained from tinea capitis patients, using the CLSI broth microdilution method. We tested eight antifungals and used isolates collected from Western China (21), Eastern China (12), the Middle East (1), Europe (20), South Africa (7) and Canada (1).

RESULTS

The geometric means of the MICs of the antifungals for all isolates were as follows (in increasing order): posaconazole, 0.021 mg/L; terbinafine, 0.023 mg/L; voriconazole, 0.062 mg/L; amphotericin B, 0.20 mg/L; itraconazole, 0.34 mg/L; caspofungin, 0.56 mg/L; fluconazole, 4.23 mg/L; and flucytosine, 8.46 mg/L. No statistically significant differences in the susceptibility profiles of T. violaceum were detected within the geographical regions tested.

CONCLUSIONS

Posaconazole, terbinafine and voriconazole were shown to be the most potent antifungal agents against T. violaceum isolates obtained from tinea capitis patients worldwide. These results might help clinicians in developing appropriate therapies that have a high probability of successfully treating tinea capitis due to T. violaceum.

Tinea capitis favosa misdiagnosed as tinea amiantacea

INTRODUCTION

Favus of the scalp or tinea capitis favosa is a chronic dermatophyte infection of the scalp. In almost cases, favus is caused by Trichophyton schoenleinii, anthropophilic dermatophyte. It is characterized by the presence of scutula and severe alopecia. Besides the classic clinical type of tinea capitis favosa, there are many variant of clinical form which may persist undiagnosed for many years. In this work, we report an atypical form of favus to Trichophyton schoenleinii which was misdiagnosed as tinea amiantacea.

CASE-REPORT

An 11-year old girl came to the outpatient department of dermatology (day 0) with history of tinea amiantacea treated unsuccessfully with keratolytic shampoo (day - 730). She presented a diffuse scaling of the scalp with thick scaly patches and without scutula or alopecia. A diagnosis of tinea favosa by T. schoenleinii was made by mycological examination. She was treated with griseofulvin and ketoconazole in the form of foaming gel for twelve weeks. Despite treatment, clinical evolution was marked by appearance of permanent alopecia patches. The follow-up mycological examination was negative.

CONCLUSION

Because of ultimate evolution of favus into alopecia, we emphasize the importance of mycological examination in case of diffuse scaling.

Inflammatory Tinea capitis: a 12-year study and a review of the literature

Inflammatory Tinea capitis (TC) is a rare form of TC. The aim of this study was to review epidemiological, clinical and mycological profile of inflammatory TC. We present a retrospective study (1999-2010), enrolled all the cases of inflammatory TC observed at a referral hospital in the northern Tunisia. One hundred and twenty-one patients with inflammatory TC, 83 male patients (68.6%) and 38 female patients (31.4%) were enrolled. The mean age was about 8 years. A majority of TC (71.9%) were in patients lesser than 10 years of age. Positive family history and contact with animals were noted in seven and 35 cases respectively. Direct examination was positive in 110 cases (59 ectothrix, 51 endothrix) and positive cultures were obtained in 105 patients (49 Trichophyton violaceum, 31 Microsporum canis, 13 Trichophyton interdigitale complex, 12 Trichophyton verrucosum). Systemic treatment was carried out in 115 patients with griseofulvin, in one with terbinafine. A complete recovery was noted in 88 cases; and persistent alopecia in 28 cases. The inflammatory TC is rare, but more common in rural families. The disease mostly affected male genders (68.6%) and T. violaceum remains the common pathogen of inflammatory TC in northern Tunisia.

A random comparative study of terbinafine versus griseofulvin in patients with tinea capitis in Western China

OBJECTIVE

To compare the efficacy and safety of terbinafine with griseofulvin in the treatment of tinea capitis in Western China.

METHODS

Children (2-14 years of age) with clinically diagnosed and potassium hydroxide microscopy-confirmed tinea capitis were randomized into three groups: group GRI4 received 4 weeks of griseofulvin; group TBF2 received 2 weeks of terbinafine; and Group TBF4 received 4 weeks of terbinafine. Clinical and mycological evaluations were done in 0, 2, 4, and 8 weeks and 1 year after therapy started. The isolated pathogenic fungi were evaluated for in vitro susceptibility by detecting the minimal inhibitory concentration (MIC) against terbinafine, griseofulvin, itraconazole, and ketoconazole.

RESULTS

The clinical effectiveness rate of GRI4, TBF2, and TBF4 were 100% (95% CI-confidence interval: 82-100%), 96.3% (95% CI: 81-100%), and 100%(95% CI: 85-100%), respectively, at week 8 and 100% after 1 year for the 3 groups; clinical cure rates were 84.2%(95% CI: 77-99%), 85.2%(95% CI: 71-98%), and 78.3%(95% CI: 61-95%), respectively, at week 8 and 100% after 1 year for all agents; mycological cure rates were 100%(95% CI: 74-100%), 95.0%(95% CI: 74-100%), and 94.1%(95% CI: 50-93%) at week 8 and 100% after 1 year for the 3 groups. In vitro, all patient-derived cultures were sensitive to the four antifungal agents.

CONCLUSION

Data from the clinical trial and in vitro antifungal activity indicated that terbinafine is efficacious and well tolerated in the treatment for Trichophyton infections (T. violaceum; Arthroderma vanbreuseghemii; and T. tonsurans) of the scalp, i.e., a 2- to 4-week course of terbinafine is as effective as a 4-week course of griseofulvin; in fact, a 2-week course of terbinafine is sufficient. Terbinafine is an effective alternative to griseofulvin against tinea capitis of Trichophyton infections.

Arthroderma vanbreuseghemii infection in three family members with kerion and tinea corporis

We present a familial infection caused by Arthroderma vanbreuseghemii. The proband is a 4-year-old boy, who had played with rabbits at his rabbit-farm neighbor. He complained of pruritus and pain in his scalp, which displayed redness, alopecia and painful cysts and eventually discharged pus and scabbed. Several erythema on his face and abdomen were also presented. He was diagnosed as having impetigo but antibacterial agents were not effective and his clinical condition did not improve. Several days later, his parents also developed facial erythema and scaling. The development of a kerion in the boy and tinea corporis in his parents were diagnosed based on the positive KOH examination. Morphologic and biochemical characteristics confirmed that their infections were caused by the zoophilic Trichophyton mentagrophytes, while sequencing of the internal transcribed spacer (ITS) 1/4 polymerase chain reaction products, amplified from primary culture isolates, established its Arthroderma vanbreuseghemii lineage. Random amplified polymorphic DNA (RAPD) analysis indicated these isolates might be the same strain and that infection cruciata occurred in this family. Semi-quantitative analysis of these strains indicated multiple and main enzymatic activities of alkaline phosphatase, beta-glucosaccharase. The boy was cured through treatment with itraconazole 100 mg/day orally in combination with topical washes with 2% ketoconazole shampoo, and his parents were successfully treated by topical application of terbinafine cream.

Substrate adaptation of Trichophyton rubrum secreted endoproteases

Trichophyton rubrum is the most common pathogen caused the dermatophytosis of nail and skin in human. The secreted proteases were considered to be the most important virulence factors. However, the substrates adaptation of T. rubrum secreted proteases is largely unknown. For the first time, we use the keratins from human nail and skin stratum corneum as the growth medium to investigate the different expression patterns of T. rubrum secreted endoproteases genes. During grow in both keratin-containing media SUB7 and MEP2 were the highest expressed gene in each family. These results indicated that SUB7 and MEP2 may be the dominant endoproteases secreted by T. rubrum during host infection and the other proteases may play a supplementary role. The direct comparison of T. rubrum grown on skin and nail medium showed different substrate favorite of secreted endoproteases. The genes MEP2, SUB5, SUB2 and SUB3 were more active during growth in skin medium, possibly these proteases have a higher affinity for skin original keratins. While the structures of SUB1, SUB4, and MEP4 maybe more suitable for the degradation of nail original keratins. This work presents useful molecular details for further understanding the pathogenesis of secreted proteases and the wide adaptation of T. rubrum.