Candida tropicalis in environmental and animal reservoirs: a systematic review from a One Health perspective.

Candida tropicalis is an important opportunistic yeast increasingly associated with antifungal resistance across different ecological contexts. We systematically reviewed research articles published up to June 1, 2026, to investigate the distribution of C. tropicalis in non-clinical niches and synthesize evidence on its susceptibility to clinically relevant antifungals and agricultural fungicides, virulence-associated traits, and resistance-related genes. Database searches were conducted in PubMed, Web of Science, ScienceDirect, Google Scholar, Scopus, and SciELO. A total of 35 eligible studies were included, comprising 1,011 C. tropicalis isolates. Most isolates originated from environmental sources (694/1,011; 68.6%), mainly soil (159/694; 22.9%) and beach sand (124/694; 17.9%), whereas 317/1,011 (31.4%) were recovered from animal sources. Across all studies, 769 antifungal resistance or reduced-susceptibility events were identified, including 422 (54.9%) among environmental isolates and 347 (45.1%) among animal-derived isolates. Resistance was predominantly associated with azole antifungals, particularly fluconazole (FLC) (358/1,008; 35.5%; 95% CI: 32.6-38.5%), followed by itraconazole (ITZ) (116/511; 22.7%; 95% CI: 19.3-26.5%) and voriconazole (VOR) (98/418; 23.4%; 95% CI: 19.6-27.7%). Evidence of cross-resistance between clinical azoles and agricultural fungicides was reported in six of the seven studies evaluating both compound classes. Furthermore, isolates frequently exhibited virulence-associated phenotypes, including strong biofilm formation (94/130; 72.3%; 95% CI: 64.1-79.3%) and strong hemolytic activity (48/80; 60.0%; 95% CI: 49.0-70.0%). Molecular analyses identified recurrent ERG11 mutations and the overexpression of efflux pump-related genes, which are also recognized as major resistance mechanisms in clinical C. tropicalis isolates. Collectively, these findings demonstrate that environmental and animal-derived C. tropicalis isolates frequently exhibit azole resistance, including cross-resistance to agricultural fungicides, together with virulence-associated phenotypes and resistance-related genetic mechanisms consistent with those reported in clinical isolates - underscoring the role of these reservoirs in the maintenance and dissemination of resistant and virulent lineages within a One Health framework.