Emergence of resistant tinea corporis in a low socioeconomic setting

BACKGROUND: Treatment resistance in tinea corporis has emerged recently, resulting in unresponsive infections. OBJECTIVES: To assess the resistance of recalcitrant dermatophytoses on glabrous skin and to understand the situation in Sri Lanka. METHODS: A descriptive, observational, cross-sectional study was conducted involving nine hospitals representing all nine provinces in Sri Lanka over 6 months, starting from June 2019. All patients with dermatophyte infections in the glabrous skin were included. Sociodemographic characteristics, symptoms and prior treatment were collected. Antifungal sensitivity testing was done by a method adopted from EUCAST E.DEF 9.3 (2015). Quality control was done to ensure the accuracy of results. RESULTS: The study included 127 isolates of dermatophytes for testing antifungal sensitivity. Trichophyton mentagrophytes comprised the majority, with 79 isolates, while there were 48 isolates of T. rubrum. The mean minimum inhibitory concentration (50th percentile; MIC50) of terbinafine was 0.064 g mL-1 for T. mentagrophytes. A significant number of isolates (8 of 32, 25%) had an MIC higher than the epidemiological cutoff of 0.125 g mL-1 set by EUCAST for terbinafine, indicating a higher likelihood of clinical failure. The MIC50 for itraconazole was 0.25 g mL-1. Considering the epidemiological cutoff of 0.25 g mL-1 for T. mentagrophytes, 33 of 79 (42%) isolates tested for itraconazole were higher. CONCLUSIONS: Itraconazole may need to be used in the treatment, with close monitoring of the response of the patients.