Antifungal resistance in yeasts from One Health perspective: A Brazilian study

Abstract

Environmental exposure to fungicides can induce cross-resistance in filamentous fungi, but little is known about their effects on medically important yeasts. This multicenter study investigated the resistance in Candida isolated from different sources and evaluated the influence of clinical and environmental antifungals. Different yeasts were collected from patients, hospital environments, swine, poultry and their surroundings in four different states of Brazil. A total of 571 isolates were identified, of which 82.5 % belonged to the genus Candida. Antifungal susceptibility testing revealed that C. tropicalis had the highest resistance rate (12 %) to fluconazole, followed by C. glabrata and C. albicans with resistance rates of 8 % and 6 %, respectively. Resistance to micafungin was most common in C. glabrata (15 %). For amphotericin B, we identified two non-wild-type isolates, one belonging to the C. tropicalis species and the other to C. glabrata. Most resistant isolates were recovered from patients; however, resistance was also observed in animal and environmental isolates. In addition, susceptibility to tebuconazole, an environmental azole, was evaluated and a cut-off value of 8 μg/mL was proposed to assess potential resistance. Among the isolates, 10.5 % had a high minimum inhibitory concentrations (MIC) for tebuconazole. Moreover, cross-resistance is possible to occur, as 3.6 % of Candida isolates were resistant to fluconazole and had high MIC for tebuconazole, particularly C. albicans, C. tropicalis, and C. krusei. This study demonstrates the importance of monitoring yeast resistance to antifungals and environmental fungicides in different niches, and calls for a multidisciplinary approach to understand multiple factors involved in resistance development.