Expansion of a predominant azole-resistant Candida tropicalis genotype from 2012 to 2018: evidence from orchard environments in Taiwan.

Abstract

A predominant fluconazole-resistant Candida tropicalis clade 4 genotype, based on MLST analysis, causing candidemia in humans in several tropical countries was detected in the environment in a 2012 orchard survey in Taiwan, which is an emerging one health issue. This follow-up study investigated clade 4 azole-resistant C. tropicalis in orchards, comparing the 2012 survey data with the 2018 survey findings. We compared C. tropicalis isolated from the same 53 orchards, including 23 wax apple, 17 grape, and 13 papaya orchards, in both the 2012 and 2018 surveys. We collected samples of fruits, soils, and irrigation water from environment and swab samples from armpit and hand, as well as oral mouth rinses of the farmers. Overall, the rate of fluconazole-resistant C. tropicalis from the 2018 survey was significantly higher than that from the 2012 survey (27/55 vs. 9/46, p = 0.003). Furthermore, we found that the use of azole fungicides was associated with the detection of azole-resistant C. tropicalis. Notably, 77.8% (7/9) of the azole-resistant isolates in the 2012 survey and 92.6% (25/27) in the 2018 survey were genetically related and belonged to the clade 4 genotype. Our findings demonstrate that the rate of fluconazole-resistant C. tropicalis from orchards increased significantly and the clade 4 drug-resistant C. tropicalis spread widely in orchard environments, especially among grape ones. Our findings show that different types of crop had different cultivation habits. Hence, grape orchard environment is a priority to conduct intervention for cultivation habits of farmers, especially on azole fungicide use in Taiwan.