Emergence of Trichophyton tonsurans-A Retrospective Multicentre Study of the Dermatophyte Spectrum in Germany

Abstract

Background: In mid-2024, German media reported increasing fungal infections by Trichophyton tonsurans linked to visits to barbershops. However, epidemiological data confirming a rise in tinea capitis and tinea corporis due to Trichophyton tonsurans are lacking.

Objectives: This study assesses dermatophyte species and clinical types of infections in German university hospitals in 2018 and 2023.

Patients/methods: This retrospective, multicentre study analyses mycological culture results from three Departments of Dermatology in Freiburg, Tübingen and Munich. The dermatophyte, along with the sampled body site, age and gender of the affected patient, was recorded.

Results: 1915 patients (male: 66.1%; mean age: 50 ± 24 years) with a dermatophyte-positive culture were identified. The most common dermatophyte was Trichophyton rubrum (2018: 78.7%; 2023: 66.3%) with tinea pedis and tinea unguium being the most prevalent types of infection. An increase in tinea corporis and tinea capitis was observed, with tinea capitis doubling from 4.3% to 9.3%. In 2023, Trichophyton tonsurans emerged as the prevailing dermatophyte (67.6%) in tinea capitis and as the second most frequent agent in tinea corporis (26.3%). This dominance of Trichophyton tonsurans was consistently observed across all three study centres. Trichophyton tonsurans affected patients presented a median age of 18 years in 2023 (vs. 9 years in 2018) and an amplified imbalance towards the male gender.

Conclusions: The pathogen spectrum and infection patterns have changed in Germany due to the increase of Trichophyton tonsurans infections. Intensified screening and hygiene measures, as well as adaptation of initial empiric treatment of tinea capitis, should be considered.

Keywords: Trichophyton tonsurans; tinea capitis; tinea corporis; Germany; dermatophytes; epidemiology; fungal skin infections.

FIGURE 1

Causative agents and types of infection of dermatophytoses in 2018 and 2023. Distribution of causative agents (A) and types of infection (B) of dermatophytoses of all three study centres in 2018 (left) and 2023 (right). Percentages for each category are represented in the pie charts, with colours indicating the different categories. All dermatophytes with an absolute number ≥ 7 were categorised as ‘Others’ (Table S1).

FIGURE 2

Causative agents of tinea pedis, tinea unguium, tinea corporis and tinea capitis in 2018 and 2023. Distribution of causative agents of tinea pedis (A), tinea unguium (B), tinea corporis (C) and tinea capitis (D) of all three study centres in 2018 (left) and 2023 (right). Percentages for each category are represented in the pie charts, with colours indicating the different categories. All dermatophytes with an absolute number ≥ 2 were categorised as ‘Others’ (Table S2).

FIGURE 3

Causative agents of tinea corporis plus tinea capitis in Freiburg, Tübingen and Munich in 2018 and 2023. The distribution of causative agents of tinea corporis plus tinea capitis (combined) categorised by the study centres Freiburg (A), Tübingen (B) and Munich (C) for the years 2018 (left) and 2023 (right). Percentages for each category are represented in pie charts, with colours indicating the different categories. All dermatophytes with an absolute number ≥ 2 were categorised as ‘Others’ (Table S3).

FIGURE 4

Distribution of patients with T. tonsurans‐induced tinea corporis and tinea capitis by gender and age in 2018 and 2023. Number of patients with a T. tonsurans‐positive culture segmented by gender and age for 2018 (left) and 2023 (right) for tinea corporis plus tinea capitis (A), tinea corporis alone (B) and tinea capitis alone (C).