Multidrug-resistant yeasts in fresh fruits from organic and conventional farming: quantification, species identification, and antifungal susceptibility profiles

The global increase in fungal infections and antifungal resistance has drawn attention to environmental sources of potentially pathogenic yeasts. This study investigated the fungal load and antifungal susceptibility of yeasts isolated from fresh fruits (strawberries, bananas, guavas, and apples) grown under organic and conventional farming systems. Samples were analyzed for total yeast counts (CFU g-1) and for quantification of yeasts capable of growing on medium supplemented with fluconazole (FLU) (8 and 64 µg ml-1), followed by phenotypic identification and antifungal susceptibility testing via broth microdilution. The highest fungal loads were observed in strawberries across both cultivation systems. While no differences were found between organic and conventional fruits, variation in total and FLU-tolerant yeast counts was observed between fruit types. Among 29 presumptively FLU-resistant isolates, 23 were confirmed as resistant by minimum inhibitory concentration testing. All isolates were resistant to itraconazole, and most showed cross-resistance to voriconazole. Identified species included Meyerozyma guilliermondii, Pichia kudriavzevii, Trichomonascus ciferrii, Papiliotrema laurentii, and Rhodotorula mucilaginosa, many of which are associated with invasive fungal infections. These findings highlight the potential of fresh fruits to act as reservoirs for opportunistic and multidrug-resistant yeasts. Enhanced microbiological surveillance of plant-derived foods is recommended as part of integrated public health strategies, particularly within the One Health framework.