Clinico-mycological profile of tinea capitis and its comparative response to griseofulvin versus terbinafine

Iranian National Survey on Tinea Capitis: Antifungal Susceptibility Profile, Epidemiological Characteristics, and Report of Two Strains with a Novel Mutation in SQLE Gene with Homology Modeling

BACKGROUND

The data on the epidemiological and antifungal susceptibility profile of tinea capitis (TC) in Iran has not been updated in recent decades. This report presents the Iranian epidemiological and drug susceptibility data regarding the distribution of dermatophytes species isolated by six national mycology centers for a period of one year (2020-2021).

MATERIAL AND METHODS

A total of 2100 clinical samples from individuals suspeted to TC were subjected to mycological analysis of direct microscopy and culture. For definite species identification, the culture isolates were additionally subjected to PCR-RFLP and PCR-sequencing of the ITS ribosomal DNA (ITS-rDNA) region. Antifungal susceptibility profiles for eight common antifungal drugs were determined by CLSI M38-A3 guidelines. The SQLE gene was partially amplified and sequenced in two terbinafine-resistant and two susceptible T. mentagrophytes isolates to elucidate probable substitutions involved in resistance.

RESULTS

TC (n = 94) was diagnosed in 75 children (79.8%) and 19 adults (20.2%) by direct microscopy and culture. Frequency of TC was significantly more among males (66 males = 70.2% vs 28 females = 29.8%). The prevalent age group affected was 5-9 years (39.36%). Thirty-two (34.04%) T. mentagrophytes, 27 (28.7%) T. tonsurans, 14 (14.9%) M. canis, 13 (13.8%) T. violaceum, 5 (5.32%) T. indotineae, 2 (2.1%) T. benhamiae, and 1 (1.1%) T. schoenleinii were identified as the causative agents. MIC values of isolates showed susceptibility to all antifungal agents, except for fluconazole and griseofulvin with GM MIC of 11.91 μg/ml and 2.01 μg/ml, respectively. Terbinafine exhibited more activity against isolates, with GM MIC 0.084 μg/ml followed by ketoconazole (0.100 μg/ml), econazole (0.107 μg/ml), itraconazole (0.133 μg/ml), butenafine (0.142 μg/ml), and miconazole (0.325 μg/ml). Two resistant T. mentagrophytes isolates harbored missense mutations in SQLE gene, corresponding to amino acid substitution F397L. Remarkably, one unique mutation, C1255T, in the SQLE sequence of two terbinafine-susceptible T. mentagrophytes strains leading to a change of leucine at the 419th position to phenylalanine (L419F) was detected.

CONCLUSIONS

T. mentagrophytes, T. tonsurans, and M. canis remained the main agents of TC in Iran, however less known species such as T. indotinea and T. benhamiae are emerging as new ones. Terbinafine could still be the appropriate choice for the treatment of diverse forms of TC.

Global Demographic Characteristics and Pathogen Spectrum of Tinea Capitis

Tinea capitis is an important superficial fungal infection with a global distribution. It mainly affects prepubertal children and is more common in males. Anthropophilic and zoophilic dermatophytes are responsible for most infections. The pathogen spectrum of tinea capitis varies across different regions and changes over time, and is influenced by multiple factors, such as economic development, changes in lifestyle, immigration and animal distribution. This review aimed to clarify the demographic and etiological characteristics of tinea capitis worldwide and determine the common trends of causative pathogens. By mainly analyzing the literature published from 2015 to 2022, we found that the incidence and demographic characteristics of tinea capitis remained generally stable. Zoophilic Microsporum canis, anthropophilic Trichophyton violaceum and Trichophyton tonsurans were the predominant pathogens. The pathogen spectra in different countries changed in different directions. In some countries, the main pathogen shifted to an anthropophilic dermatophyte, such as T. tonsurans, Microsporum audouinii or T. violaceum; in contrast, it shifted to a zoophilic agent, such as M. canis, in some other countries. Dermatologists are advised to continue monitoring the pathogen spectrum and implement preventive measures according to the reported changes.

Predominance of Trichophyton tonsurans causing tinea capitis: A 12-year retrospective study in the north of Iran

Background and Purpose

Among different clinical entities of dermatophytosis, tinea capitis (TC) is considered a major public health challenge in the world, especially in regions with poor health and low income. Therefore, this study aimed to provide a retrospective analysis of the patients suspected of TC who were referred to the medical mycology laboratory of Mazandaran, a northern province of Iran.

Materials and Methods

A retrospective analysis was performed on the patients suspected of TC who were referred to the medical mycology laboratory from July 2009 to April 2022. Hair roots and skin scrapings were collected from the participants. The laboratory diagnosis was confirmed by direct microscopic examination and culture. Finally, 921 out of 11095 (8.3%) patients were suspected of TC.

Results

Based on the findings, TC was confirmed in 209 out of 921 patients (22.7%). In terms of gender, 209 TC patients (75.1%) were male. Moreover, the male to female ratio of TC patients was 1:3.0. Trichophyton tonsurans (146/174, 83.91%) was the most etiological agent, followed by T. mentagrophytes (13/174, 7.47%), T. violaceum (9/174, 5.17%), Microsporum canis (3/174, 1.71%), T. verrucosum (2/174, 1.15%) and T. rubrum (1/174, 0.57%). Besides, endothrix (77.0%) was the most prevalent type of hair invasion.

Conclusion

The results revealed the predominance of T. tonsurans, as a causative agent of TC. Despite the prevalence of TC, the absence of appropriate consideration highlights that it is a neglected complication among children.

High Trichophyton violaceum-Induced Tinea Capitis with Isolation of Many Non-Dermatophyte Molds in Scalp Scrapings in Patients Referred to a Dermatology Clinic in Addis Ababa, Ethiopia

Objective

This work aimed to determine the magnitude of tinea capitis, the diversity and species composition of fungi, and the predominant dermatophytes implicated in causing tinea capitis.

Methods

A prospective, cross-sectional study was conducted at a dermatology clinic. Scalp scrapings were collected and cultured, and dermatophyte and non-dermatophyte molds were identified.

Results

Of 364 scalp scrapings, fungi were recovered from 301 (82.7%) clinical samples. About 60.7% of the samples were collected from women, while 39.3% were collected from male study subjects. The association between the magnitude of scalp ringworm and gender was not statistically significant (P = 0.105). Two hundred eighty study subjects were less than 15 years of age, of which 254 were culture positive. The association of tinea capitis and the age of patients was statistically significant (P = 0). Three hundred forty-nine fungal isolates were isolated, of which 54.2% were dermatophytes, while 45.8% were non-dermatophyte molds. The occurrence of dermatophytes in their decreasing order was T. violaceum (138; 73%), Trichophyton mentagrophytes (18; 9.5%), Trichophyton tonsurans (16; 8.5%), Trichophyton verrucosum (8; 4.5%), Microsporum audouinii (7; 3.7%), Trichophyton schoenleinii (1; 0.5%), and Trichophyton soudanense (1; 0.5%).

Conclusion

A high prevalence rate of T. violaceum-induced tinea capitis was reported. The magnitude of scalp ringworm in adults was remarkably high. Therefore, conducting a nationwide epidemiological survey on tinea capitis regardless of age is suggested. The isolation of many non-dermatophyte molds in the current study may shade questions about the perception that tinea capitis is caused by dermatophytes only. Therefore, studies on their potential pathogenic role on skin and skin-related (nail and the scalp) infections appear to be an active field of research.

[Trichophyton tonsurans-an emerging pathogen in wrestling in Germany]

Trichophyton (T.) tonsurans is considered as the main causative agent of tinea gladiatorum (ringworm) in contact and martial arts worldwide and regularly leads to outbreaks. In the national wrestling squad in Leipzig, dermatophytoses occurred frequently and recurrently in children and adolescents for over a 2-year period. The wrestlers came to the dermatologist's office for clinical examination and sampling. Dermal scales and hair roots as well as smears were examined mycologically with fluorescence optical preparation, fungal culture, and polymerase chain reaction (PCR) for dermatophyte DNA. Sequencing of the dermatophyte rDNA served as culture confirmation test. Environmental investigations in the wrestler training center included contact cultures and smears from surfaces, in particular from the mats. T. tonsurans was culturally and/or with PCR detectable in 21 out of 25 children and adolescents plus one trainer. T. tonsurans grew in one of ten contact cultures of mats and floors in the wrestling training center, and T. interdigitale was found in another culture. Smears from the mats resulted in a culture of T. tonsurans detection twice. The PCR was positive for T. tonsurans three times. Within 14 days, T. tonsurans developed small, flat, radiating, granular and white-colored colonies with a mahogany-brown reverse side on the fungal culture media. The sequencing of the internal transcribed spacer (ITS) region of the rDNA and the translation elongation factor 1 α (TEF 1 α) gene confirmed the species T. tonsurans in all cases. T. interdigitale that was found from a mat was also identified by sequencing. Eight T. tonsurans strains were subjected to in vitro susceptibility testing to terbinafine. All isolates were sensitive to terbinafine in vitro with minimal inhibitory concentrations of ≤ 0.1 µg/ml.