High MICs for antifungal agents in yeasts from an anthropized lagoon in South America

The lagoons are fragile ecosystems used by several species as a refuge and breeding area, and it is also a place where certain communities practice fishing activity. With increasing urbanization around this ecosystem, pesticides used in agriculture and untreated urban wastewater are drained into the river basin, resulting in the dispersion of organic matter and antifungals used by the population and farmers. These may favor the selection of resistant pathogens directly into the environment, a concern since several fungi have emerged as pathogens in the last decades. In this study, we investigated the presence in an impacted lagoon by potentially resistant yeasts to antifungal agents. We evaluated their capacity for producing extracellular enzymes that could act as virulence factors. Water samples from the Tramandaí lagoon were analyzed for the presence of pesticides using the SPE-LC-ESI-MS/MS. Tricyclazole, carbendazim, azoxystrobin, thiabendazole, and tebuconazole were found. Twenty-eight yeast species were isolated, including the multidrug-resistant Candida haemulonii, and species with high minimal inhibitory concentrations (MICs) for clinical antifungal agents. Around 93% of the isolates had MIC values above the resistance breakpoints established for Candida species for at least two antifungal agents. And 27% had high MICs values for fluconazole, terbinafine, amphotericin B, and caspofungin. Tebuconazole MICs values were highly associated with MICs for fluconazole, terbinafine, and amphotericin B, and significant correlations between high MICs for antifungal agents and enzyme production were found. The results indicated that the lagoon is a reservoir of resistance genes and a potential source for fungal infection, highlighting the importance of the One Health approach and the integrated vision of the ecosystem when managing these environments.