Insights into the Multi-Azole Resistance Profile in Species Complex

The complex (, , and var. ) is composed of emerging, opportunistic human fungal pathogens able to cause invasive infections with high rates of clinical treatment failure. This fungal complex typically demonstrates resistance to first-line antifungals, including fluconazole. In the present work, we have investigated the azole resistance mechanisms expressed in Brazilian clinical isolates forming the complex. Initially, 12 isolates were subjected to an antifungal susceptibility test, and azole cross-resistance was detected in almost all isolates (91.7%). In order to understand the azole resistance mechanistic basis, the efflux pump activity was assessed by rhodamine-6G. The complex exhibited a significantly higher rhodamine-6G efflux than the other non- species tested (, , and ). Notably, the efflux pump inhibitors (Phe-Arg and FK506) reversed the fluconazole and voricolazole resistance phenotypes in the species complex. Expression analysis indicated that the efflux pump (, , and ) and genes were not modulated by either fluconazole or voriconazole treatments. Further, gene sequencing revealed several mutations, some of which culminated in amino acid polymorphisms, as previously reported in azole-resistant spp. Collectively, these data point out the relevance of drug efflux pumps in mediating azole resistance in the complex, and mutations in ERG11p may contribute to this resistance profile.