Mixed infections are a critical factor in the treatment of superficial mycoses

Superficial fungal infections of the skin, nails and hair are common with Trichophyton rubrum and Candida albicans being the main pathogens. Yet, in some patients, mycological cultures show growth of more than one fungal agent in the same anatomical region. This study analyses prevalence, frequency and fungal agents found in superficial fungal mixed infections and discusses consequences for diagnostics and treatment. Mycological data obtained between January 2006 and December 2015 from clinical specimens from a total cohort of 7733 patients with suspected fungal infections were retrospectively analysed. All specimens were cultured on Sabouraud's dextrose and dermatophyte agar. Patients were included in this study, if more than one fungal species developed in culture. Mixed infections account to 6% of all superficial fungal infections. In more than half of the cases, a combination of dermatophyte and yeast is found, mostly concerning foot lesions. Male patients between 60 and 80 year are most commonly affected (39% of mixed infections). Rare species are found in distinctly higher percentages in fungal mixed infections than in general. Sampling of all regions of suspected fungal infection and cultural proof are essential for purposeful systemic therapy. Delayed treatment of fungal infections may enable secondary co-infection by species usually considered little pathogenic.