ntifungal susceptibility of environmental Aspergillus spp. strains isolated in Argentina.

HERMIDA ALAVA KS; BRITO DEVOTO T; SAUTUA F; GORDO M; SCANDIANI M; FORMENTO N; LUQUE A; TOSCANINI MA; CARMONA M; CUESTAS ML

Congreso; 19TH INFOCUS.; 2021

Objectives: Resistance to azole drugs in Aspergillus fumigatus has been selected both from clinical exposure to therapeutic drugs as well as environmental exposure to antifungal azoles used to control crop pathogens. Resistance due to agricultural exposure to fungicides is well documented in A. fumigatus, but little is known of this influence in other Aspergillus species. The aim of this work is to study the susceptibility profile of non-fumigatus Aspergillus environmental isolates against clinical triazoles. Methods: Thirty-three strains of Aspergillus spp. were isolated from chickpea and soybean seeds from Buenos Aires, Argentina. Strains were identified to species level by partial β-tubulin (Bt2) and calmodulin (CMD) gene sequencing. Microdilution broth antifungal susceptibility testing was performed following EUCAST E.DEF 9.3.2 guidelines. Amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC) and posaconazole (POS) were evaluated. Results: Seventeen (55%) strains were identified as Aspergillus flavus, 7 (21%) as Aspergillus niger, 5 (15%) as Aspergillus ochraceous, 2 (6%) as Aspergillus tamarii, and 1 (3%) as Aspergillus ostianus. Regarding A. flavus, 6 isolates showed MIC values above the Epidemiological Cut-Off Values (ECOFFs); 4 showed increased MIC to VCZ, 1 to ITC, and 1 to VCZ and ITC. As for A. niger, 5 isolates showed high MIC to ITC only. High MIC values to VCZ were found in 4 A. ochraceus isolates (2 isolates showed MIC values = 4 µg/ml and 2 isolates showed MIC values ≥ 8 µg/ml and in 1 A. tamarii isolate, MIC values were high for VCZ and ITC (MIC ≥ 8 µg/ml) (Table 1).Conclusion: Environmental non-fumigatus Aspergillus isolates exposed to triazolic compounds used in agricultural practices showed cross-resistance to azole antifungals used in the clinics. The environmental route of resistance development in the clinic might become a threat as it occurred with A. fumigatus. Hence, optimization and regulation of agricultural practices is mandatory for the high risk of resistance acquisition in naïve patients through the environment. In parallel, novel classes of antifungals for both agriculture and clinics should be developed in order to avoid or delay resistance.