Clinical and Mycological Profile of Dermatophyte Infections in South-East England: A 17-Year Retrospective Analysis (2006-2023).

Abstract

Background: Dermatophyte infections, which are among the most prevalent fungal infections globally, affect skin, hair and nails, accounting for significant morbidity. Epidemiological data on dermatophytosis in the UK are limited. One notable study in 2007 provided insights into the causative agents of dermatophyte infections in the UK; however, no extensive regional analysis has been published since.

Objectives: The aim of this study was to provide a contemporary understanding of the epidemiology and causative agents of dermatophytosis in South-East England.

Method: This retrospective laboratory database review analysed all samples of skin, hair and nail that underwent mycological examination (microscopy and culture) in a single diagnostic microbiology laboratory in South-East England over a period of 17 years (2006-2023).

Results: Between 2006 and 2023, a total of 34,624 samples were collected, with the majority being nail (n = 26,362), followed by skin (n = 8015), hair (n = 246) and one unknown sample type. Fungal culture yielded positive results in 22.0% (n = 7601) of samples, with dermatophytes comprising 89.4% (n = 6794) and non-dermatophyte moulds 4.8% (n = 366). Trichophyton species dominated dermatophyte isolates at 99.3% (n = 6745), followed by Microsporum (0.5%, n = 37) and Epidermophyton (0.2%, n = 12). Onychomycosis of toenails was the most common infection (n = 2774), predominantly affecting males (median age: 48 years); the cause was Trichophyton rubrum in 80.5% of cases, and infection was confirmed by positive direct microscopy in 80.3%. Tinea pedis (n = 416), conversely, was more common in females (median age: 50 years). Other dermatophyte infections included tinea corporis (n = 179), onychomycosis of the fingernails (n = 99), tinea cruris (n = 91), tinea capitis (n = 82), tinea manuum (n = 56) and tinea faciei (n = 14). Trichophyton rubrum was the primary causative agent across all body sites except for tinea capitis, where Trichophyton mentagrophytes (30.5%), Trichophyton violaceum (19.5%) and Trichophyton tonsurans (15.9%) prevailed. Non-anthropophilic species (n = 165) caused infection across all body sites, but most caused tinea capitis (25.5%) and tinea corporis (20.0%) and affected younger individuals (median age: 29 years). Trichophyton mentagrophytes was the most common non-anthropophilic dermatophyte. Over the 17 years, the prevalence of Trichophyton interdigitale declined by 20%, while Trichophyton rubrum increased from 78.4% in 2006 to 82.0% in 2023. No cases of Trichophyton indotineae were identified.

Conclusion: This study highlights the high prevalence of Trichophyton rubrum as a cause of dermatophyte infections in South-East England. Non-anthropophilic infections are rare and demographically distinct, guiding case management and public health strategies.