GD06 Terbinafine-resistant <i>Trichophyton indotineae</i>: an analysis of confirmed cases in our regional National Health Service board

Abstract The emergence of antifungal-resistant dermatophytosis has been identified as an increasing global problem, given the limited number of available antimycotics and clinical variances in in vitro and in vivo susceptibilities. A strain of terbinafine-resistant Trichophyton indotineae (previously known as Trichophyton mentagrophytes genotype VIII) typically causes a widespread itchy, inflammatory eruption and was first confirmed within Europe in 2021 (Brasch J, Gräser Y, Beck-Jendroscheck V et al. ‘Indian’ strains of Trichophyton mentagrophytes with reduced itraconazole susceptibility in Germany. J Dtsch Dermatol Ges 2021; 19: 1723–7). There is increasing evidence of its acquisition and transmission beyond its known areas of endemicity [Siopi M, Efstathiou I, Theodoropoulos K et al. Molecular epidemiology and antifungal susceptibility of Trichophyton isolates in Greece: emergence of terbinafine-resistant Trichophyton mentagrophytes type VIII locally and globally. J Fungi (Basel) 2021; 7: 419]. Following a challenging case of this resistant fungal strain in our clinic, we aimed to assess whether our regional National Health Service (NHS) board was also seeing an increased incidence of this resistant organism, and which antimycotics were being chosen to eradicate infection and their clinical rates of success. After obtaining Caldicott Guardian ethical approval, details of all confirmed cases of T. indotineae on mycological culture in our regional NHS board within the past 12 months were collected by our local microbiology department in a password-protected database. Data analysis was performed using Microsoft Excel. In total, eight patients were confirmed to have T. indotineae infection (one of whom had three separate positive mycological cultures) over the past 12 months. Seven of these patients were of South Asian ethnicity and one patient was originally from Tanzania. These patients were aged between 31 and 67 years and were predominantly female (six of eight, 75%). Three patients had a documented recent travel history (one to Tanzania, one to Pakistan and one to Bangladesh) and three patients had HIV and haemoglobin A1c testing performed. Affected skin sites sampled varied and included the trunk, groin and limbs. Of the 10 positive mycological culture samples, three were terbinafine resistant (three of 10, 30%), 10 of 10 were itraconazole sensitive, seven of 10 were micoconazole sensitive, two of 10 were voriconazole sensitive and one of 10 was griseofulvin sensitive. Our findings confirm that terbinafine-resistant T. indotineae has been detected in our regional NHS board, and identified strains appeared to be sensitive in vitro to alternative antimycotics (although they may still be clinically resistant in practice). Globally, all dermatologists should be aware of this emerging organism, perform mycological testing if suspecting a dermatophytosis and liaise with local microbiology teams where terbinafine resistance is confirmed, to allow correct treatment and national monitoring.