Abstract
Resistance to triazoles in Aspergillus fumigatus has been reported in azole-naive patients in Europe, Asia, Australia and North America. This resistance has been linked to fungicide-driven mutations in the cyp51A gene and its promoter region. We investigated the presence of environmental azole-resistant A. fumigatus strains related to the use of azole fungicides in Colombia. Soil samples were collected from flower beds, flower fields and public gardens from the outskirts, suburbs and city centre of Bogotá. Out of the 86 soil samples taken, 17 (19.8%) grew A. fumigatus of whom eight (9.3%) contained 40 strains able to grow on azole-containing itraconazole and/or voriconazole supplemented media. All but one triazole-resistant strains were isolated from soil samples collected from flower fields and flower beds (39/40). Importantly, the majority had the TR46/Y121F/T289A, TR34/L98H, and TR53 molecular resistance mechanisms and one azole resistant strain had a wild-type cyp51A gene. Soil samples from flower fields and beds contained 4 azole fungicides (penconazole, difenoconazole, tetraconazole and tebuconazole) above the limit of detection. Our findings underline the need for extensive investigations to determine azole-resistant A. fumigatus prevalence in both clinical and environmental samples in other regions of Latin America.
Highlights
Given this possible association between the use of DMI in agriculture and the emergence of azole-resistant A. fumigatus[3,4,12,13] and the fact that Colombia is a country with a high flower production, we recently evaluated the presence of environmental resistance to azoles of medical importance in A. fumigatus isolated from flower fields and described the first environmental azole-resistant A. fumigatus strains in South America[14]
Results showed a great diversity in molecular resistance mechanism with a larger number of strains harbouring TR46/Y121F/T289A (n = 17; 80.9%) followed by TR53 (n = 2) and TR34/L98H (n = 1) and one azole resistant strain was cyp51A wild-type
All A. fumigatus strains harbouring the TR46/Y121F/T289A mutation grew on voriconazole and itraconazole plates whereas TR53, TR34/L98H and the cyp51A wild-type strains grew only on itraconazole-containing agar plates
Summary
According to the pesticide report of the Ministry of Agriculture and Integrated Rural Development of Colombia for the period 2006–2013, fungicides ranked second in sales after herbicides (43 and 34%, respectively)[10]. Fungicides are authorized for use in a large variety of agricultural applications including flower production[11]. Given this possible association between the use of DMI in agriculture and the emergence of azole-resistant A. fumigatus[3,4,12,13] and the fact that Colombia is a country with a high flower production (second producer worldwide), we recently evaluated the presence of environmental resistance to azoles of medical importance in A. fumigatus isolated from flower fields and described the first environmental azole-resistant A. fumigatus strains in South America[14]. Antifungal activity of flutriafol against wild-type A. fumigatus was investigated
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