Dermatophyte contamination of hair clippers and cleaning brushes in Copenhagen hair salons.

BACKGROUND

Tinea capitis (TC) is a fungal scalp infection. In 2024, a sudden increase in TC cases caused by Trichophyton (T.) tonsurans was observed among young men in Copenhagen, Denmark. Most of the affected individuals had recently received haircuts with electric hair clippers at hair salons prior to symptom onset. We hypothesized that electric hair clippers could be a source of infection spread.

OBJECTIVES

The study objective was to investigate whether anthropophilic dermatophytes could be found in electric hair clippers from hair salons.

METHODS

Hair salons were randomly selected from municipalities in Copenhagen. Sampling was done by swabbing the head of the electric clippers and brushes with a sterile cotton swab moistened with sterile saline water. The swab was thereafter inoculated onto a Sabouraud dextrose agar plate supplemented with cycloheximide and chloramphenicol and incubated at 25-28°C for 4 weeks. Plates with fungal growth were submitted for species identification based on macro- and micromorphological characteristics and molecular diagnostics.

RESULTS

133 samples were collected from 57 hair salons, of which 122 were from electric clippers and 11 from cleaning brushes. After 4 weeks of incubation, eight out of the 133 samples from five salons were confirmed positive for T. tonsurans. Of these, five originated from clippers and three from brushes.

CONCLUSIONS

The recent outbreak of T. tonsurans in Denmark is most likely attributable to transmission via electric hair clippers and indirectly through cleaning brushes, as T. tonsurans was isolated from 3/11 (27%) brush samples and 5/122 (4%) hair clipper samples collected from 5/57 (9%) hair salons in Copenhagen. These findings highlight the importance of thorough disinfection of hairdressing tools between each customer to prevent the transmission of fungi.