Genetically closely related azole-resistant Candida tropicalis in environments can be a threat to healthcare

[[abstract]]Objective: We would like to investigate the diversity of yeasts recovered from farms and the farmers. Furthermore, we characterized the genetic relatedness of azole-resistant Candida tropicalis recovered from environments and patients. Methods: Yeasts recovered from farms (fruits, soils, and water) and the farmers (armpit swabs, hand swabs, and oral rise) were identified by ribosomal DNA sequencing and the drug susceptibilities of C. tropicalis were determined by broth microdilution assay. Multilocus sequence typing was performed to explore the genetic relatedness of C. tropicalis recovered from agricultural and clinical settings. Results: Of 691 yeast isolates, comprised of 25 genera from 81 farms, 444 (64.3%) were recovered from environments. Among 98 species, 35 (35.7%) species including 286 isolates, have been reported to cause diseases in humans. Of the 5 Candida species commonly causing diseases in humans, C. krusei (26/30, 86.7%, P = 0.012) and C. tropicalis (59/65, 90.8%, P = 0.0004) were prevalent in environments, whereas C. albicans (37/39, 94.9%, P < 0.0000001), C. glabrata (3/3, 100%, P < 0.0000001), and C. parapsilosis (29/30, 96.7%, P < 0.0000001) were in humans. Interestingly, 7 of the 10 fluconazole-resistant and 16 of the 27 triadimenol-resistant C. tropicalis were belonged to diploid sequence type (DST) 225. Importantly, 21 of the 25 fluconazole-resistant and 34 of the 40 triadimenol-resistant clinical C. tropicalis collected in Taiwan Surveillance of Antimicrobial Resistance of Yeasts in 2014 were genetically closely related to DST 225. Conclusion: We have recovered pathogenic yeasts commonly causing diseases in humans from environments. The fact that genetically closely related fluconazole-resistant C. tropicalis exists in both environments and patients emphasizes a potential route for pathogenic yeasts to be transmitted from environments to humans and vice versa