Towards an Early Clinical and Biological Resistance Detection in Dermatophytosis: About 2 Cases of Trichophyton indotineae

Antifungal resistance in dermatophytes - review of the epidemiology, diagnostic challenges and treatment strategies for managing Trichophyton indotineae infections

INTRODUCTION

There is an increasing number of reports of Trichophyton indotineae infections. This species is usually poorly responsive to terbinafine.

AREAS COVERED

A literature search was conducted in May 2024. T.indotineae infections detected outside the Indian subcontinent are generally associated with international travel. Reports of local spread are mounting.As a newly identified dermatophyte species closely related to the T. mentagrophytes complex with limited genetic and phenotypic differences, there is an unmet need to develop molecular diagnosis for T. indotineae. Terbinafine has become less effective as a first-line agent attributed to mutations in the squalene epoxidase gene (Leu393Phe, Phe397Leu). Alternative therapies include itraconazole for a longer time-period or a higher dose (200 mg/day or higher). Generally, fluconazole and griseofulvin are not effective. In some cases, especially when the area of involvement is relatively small, topical non-allylamine antifungals may be an option either as monotherapy or in combination with oral therapy. In instances when the patient relapses after apparent clinical cure then itraconazole may be considered. Good antifungal stewardship should be considered at all times.

EXPERT OPINION

When both terbinafine and itraconazole are ineffective, options include off-label triazoles (voriconazole and posaconazole). We present four patients responding to these newer triazoles.

Trichophyton indotineae, an Emerging Drug-Resistant Dermatophyte: A Review of the Treatment Options

Background: Dermatophytosis is a prevalent superficial infection caused by filamentous fungi, primarily affecting the skin and/or its appendages. In recent years, there has been a notable increase in mycotic strains resistant to standard antifungal therapies, including Trichophyton indotineae, a dermatophyte of the Trichophyton mentagrophytes complex. This review aims to provide a comprehensive overview of the treatment options for T. indotineae, elucidating their effectiveness in managing this challenging mycotic infection. Methods: For this review, a search was conducted in the PubMed, Scopus, Web of Science, Embase, and Google Scholar databases, encompassing all published data until March 2024. English-language articles detailing therapy outcomes for patients confirmed to be affected by T. indotineae, identified through molecular analysis, were included. Results: Itraconazole was shown to be a good therapeutic choice, particularly when administered at a dosage of 200 mg/day for 1-12 weeks. Voriconazole was also demonstrated to be effective, while terbinafine exhibited a reduced response rate. Griseofulvin and fluconazole, on the other hand, were found to be ineffective. Although topical treatments were mostly ineffective when used alone, they showed promising results when used in combination with systemic therapy. Mutational status was associated with different profiles of treatment response, suggesting the need for a more tailored approach. Conclusions: When managing T. indotineae infections, it is necessary to optimize therapy to mitigate resistances and relapse. Combining in vitro antifungal susceptibility testing with mutational analysis could be a promising strategy in refining treatment selection.

High Prevalence of Terbinafine Resistance Among Trichophyton mentagrophytes/T. interdigitale Species Complex, a Cross-Sectional Study from 2021 to 2022 in Northern Parts of Iran

Treatment-resistant dermatophytosis caused by the members of the Trichophyton mentagrophytes/Trichophyton interdigitale species group (TMTISG) is increasing worldwide. We aimed to determine the prevalence of TMTISG in patients with dermatophytosis in two centers from north of Iran and detect the possible mutations in the squalene epoxidase (SQLE) gene in relevant terbinafine (TRB) resistant pathogenic isolates. From November 2021 to December 2022, 1960 patients suspected to dermatophytosis and referred to two mycology referral laboratories in the north of Iran were included in the study. Identification of all dermatophyte isolates was confirmed by RFLP of rDNA internal transcribed spacer (ITS) regions. Antifungal susceptibility testing against five common antifungals using the CLSI-M38-A3 protocol was performed. The TMTISG isolates resistant to TRB, were further analyzed to determine the possible mutations in the SQLE gene. Totally, 647 cases (33%) were positive for dermatophytosis of which 280 cases (43.3%) were identified as members of TMTISG. These were more frequently isolated from tinea corporis 131 (44.56%) and tinea cruris 116 (39.46%). Of 280 TMTISG isolates, 40 (14.3%) were resistant to TRB (MIC ≥ 4 µg/mL), all found to be T. indotineae in ITS sequencing. In SQLE sequencing 34 (85%) of TRB-resistant isolates had coincident mutations of Phe397Leu and Ala448Thr whereas four and two isolates had single mutations of Phe397Leu and Leu393Ser, respectively. Overall, the resistance of Iranian TMTISG isolates to TRB greatly occurred by a mutation of Phe397Leu in the SQLE gene as alone or in combination with Ala448Thr. Nevertheless, for the occurrence of in vitro resistance, only the presence of Phe397Leu mutation seems to be decisive.

Mapping the Global Spread of T. indotineae: An Update on Antifungal Resistance, Mutations, and Strategies for Effective Management

INTRODUCTION

The global spread of Trichophyton indotineae presents a pressing challenge in dermatophytosis management. This systematic review explores the current landscape of T. indotineae infections, emphasizing resistance patterns, susceptibility testing, mutational analysis, and management strategies.

METHODS

A literature search was conducted in November 2023 using Embase, PubMed, Scopus, and Web of Science databases. Inclusion criteria covered clinical trials, observational studies, case series, or case reports with T. indotineae diagnosis through molecular methods. Reports on resistance mechanisms, antifungal susceptibility testing, and management were used for data extraction.

RESULTS AND DISCUSSION

A total of 1148 articles were identified through the systematic search process, with 45 meeting the inclusion criteria. The global spread of T. indotineae is evident, with cases reported in numerous new countries in 2023. Tentative epidemiological cut-off values (ECOFFs) suggested by several groups provide insights into the likelihood of clinical resistance. The presence of specific mutations, particularly Phe397Leu, correlate with higher minimum inhibitory concentrations (MICs), indicating potential clinical resistance. Azole resistance has also been reported and investigated in T. indotineae, and is a growing concern. Nevertheless, itraconazole continues to be an alternative therapy. Recommendations for management include oral or combination therapies and individualized approaches based on mutational analysis and susceptibility testing.

CONCLUSION

Trichophyton indotineae poses a complex clinical scenario, necessitating enhanced surveillance, improved diagnostics, and cautious antifungal use. The absence of established clinical breakpoints for dermatophytes underscores the need for further research in this challenging field.

Dermoscopic findings in Tinea Capitis among under 18 children in dermatology polyclinic patients: a hospital-based cross-sectional study

Background

Tinea capitis is a fungal infection that affects the scalp. It is caused by a group of fungi known as dermatophytes, which thrive in warm and moist environments. In Somalia, there is a data shortage regarding dermatological conditions, especially in Mogadishu, the most populous city in the country. Tinea capitis has gone unreported despite its high prevalence in Somali dermatology clinics and the Somali diaspora in Western countries. The absence of up-to-date information hampers the capability to diagnose, treat, and prevent Tinea capitis. Therefore, the study aims to evaluate dermoscopic signs about isolated organisms and potassium hydroxide (KOH) examination.

Method

A hospital-based cross-sectional study was implemented between January and April 2023 in Mogadishu, Somalia. All eligible Tinea capitis-infected children were included in the study. Microscopically, analysis was conducted by adding 10% of KOH in fungal elements. Data were analyzed using descriptive statistics and the χ2 test at P value less than 0.05.

Results

A total of 76 tinea capitis-infected children participated in the study; 56% were age group between 5-9 years old, 68.4% were male, and 92.1% showed KOH positivity. Trichophyton violaceum (65.8%) and Trichophyton sudanense (14.5%) were the most common fungal organisms detected in the culture. comma hairs (93.10%), scales (40.80%), and corkscrews (32.90%) were the most common dermoscopic signs of tinea capitis. The demographical characteristics and dermoscopic signs of tinea capitis significantly associated with the positivity of KOH examination were age, sex, comma hairs, corkscrew hairs, broken hair, Scales, and Zigzag hair.

Conclusion

Children in Mogadishu, Somalia, bear a significant burden of Tinea Capitis infections. Trichophyton violaceum and Trichophyton sudanense were the predominant causative agents identified in the cultures. The most common dermoscopic signs of tinea capitis observed in this study were comma hairs, scales, and corkscrew patterns. Hence, early diagnosis of Tinea Capitis infections and timely, effective treatments with contact tracing are highly needed.

Multi-drug resistance Trichophyton indotineae in a stray dog

A 2.5-year-old stray dog showed signs of hair loss, mild skin crusting, and redness on extremities and trunk. The etiologic agent was confirmed as Trichophyton indotineae by sequencing of ITS region. Using the Clinical and Laboratory Standards Institute (CLSI M38-A3) guideline, antifungal susceptibility testing showed multidrug resistance phenotype against terbinafine (16 μg/mL-1), itraconazole, and some other tested antifungals (minimum inhibitory concentration, MIC≥16 μg/mL-1). However, luliconazole was found to be active in- vitro (0.016 μg/mL-1). Upon further studies, sequencing of SQLE gene showed an amino acids substitution of Phe397Leu and Ala448Thr, which is potentially linked to terbinafine resistance in Trichophyton species.

Comparison between the efficacy of terbinafine and itraconazole orally vs. the combination of the two drugs in treating recalcitrant dermatophytosis

Fungal infections are a challenging to treat cutaneous condition. Approximately 20-25% of humans are affected by superficial fungal infections that invade and multiply within keratinized tissues. To compare the efficacy of either terbinafine or itraconazole orally versus the combination of the two drugs in the treatment of recalcitrant dermatophytosis. The current study included 45 patients with recalcitrant dermatophytosis who were distributed into 3 groups (each of 15 patients); Group A received terbinafine 250 mg twice a day for 4 weeks. Group B received itraconazole 200 mg twice a day for 4 weeks. Group C received terbinafine 250 mg once daily and itraconazole 200 mg once daily for 4 weeks. The patients were followed up for 12 weeks after initiation of treatment by clinical and microbiological assessment to determine the cure rate. At the end of twelve weeks, 12 (80%) patients in group A; 13 (86.7%) patients in group B and 15 (100%) patients in group C were completely cured. Despite of cure rates being higher in the combined group C; yet results were not statistically significant (p = 0.207). Clinical cure rates were non significantly higher in itraconazole + terbinafine combined group (p = 0.207). Combination of terbinafine and itraconazole had a higher clinical and mycological cure rate when compared to the use of either drug alone as monotherapy. Further randomized, multicenter, large cohort studies are warranted to validate the use of combination antifungal treatments.