title: Heteroresistance to Itraconazole Alters the Morphology and Increases the Virulence of Cryptococcus gattii.
abstract: Cryptococcus gattii is the main etiological agent of cryptococcosis in immunocompetent individuals. The triazole drug itraconazole is one of the antifungals used to treat patients with cryptococcosis. Heteroresistance is an adaptive mechanism to counteract the stress of increasing drug concentrations, and it can enhance the ability of a microorganism to survive under antifungal pressure. In this study, we evaluated the ability of 11 C. gattii strains to develop itraconazole heteroresistance. Heteroresistant clones were analyzed for drug susceptibility, alterations in cell diameter, capsule properties, and virulence in a murine model. Heteroresistance to itraconazole was intrinsic in all of the strains analyzed, reduced both the capsule size and the cell diameter, induced molecular heterogeneity at the chromosomal level, changed the negatively charged cells, reduced ergosterol content, and improved the antioxidant system. A positive correlation between surface/volume ratio of original cells and the level of heteroresistance to itraconazole (LHI) was observed in addition to a negative correlation between capsule size of heteroresistant clones and LHI. Moreover, heteroresistance to itraconazole increased the engulfment of C. gattii by macrophages and augmented fungal proliferation inside these cells, which probably accounted for the reduced survival of the mice infected with the heteroresistant clones and the higher fungal burden in lungs and brain. Our results indicate that heteroresistance to itraconazole is intrinsic and increases the virulence of C. gattii. This phenomenon may represent an additional mechanism that contributes to relapses of cryptococcosis in patients during itraconazole therapy.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil Departamento de Farmácia, Universidade Federal de Juiz de Fora-Campus Governador Valadares, Centro, Governador Valadares, Minas Gerais, Brazil.
authors.forename: Gabriella Freitas
authors.initials: GF
authors.lastname: Ferreira
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Julliana Ribeiro Alves
authors.initials: JR
authors.lastname: Santos
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Marliete Carvalho da
authors.initials: MC
authors.lastname: Costa
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Rodrigo Assunção de
authors.initials: RA
authors.lastname: Holanda
authors.affiliation: Departamento de Farmácia, Universidade Federal de Juiz de Fora-Campus Governador Valadares, Centro, Governador Valadares, Minas Gerais, Brazil.
authors.forename: Ângelo Márcio Leite
authors.initials: ÂM
authors.lastname: Denadai
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Gustavo José Cota de
authors.initials: GJ
authors.lastname: Freitas
authors.affiliation: Universidade Vale do Rio Doce, Universitário, Governador Valadares, Minas Gerais, Brazil.
authors.forename: Áquila Rodrigues Costa
authors.initials: ÁR
authors.lastname: Santos
authors.affiliation: Universidade Vale do Rio Doce, Universitário, Governador Valadares, Minas Gerais, Brazil.
authors.forename: Priscila Batista
authors.initials: PB
authors.lastname: Tavares
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Tatiane Alves
authors.initials: TA
authors.lastname: Paixão
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, Minas Gerais, Brazil das@ufmg.br.
authors.forename: Daniel Assis
authors.initials: DA
authors.lastname: Santos
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000627:therapeutic use*; D001921:Brain / Q000382:microbiology; D049109:Cell Proliferation / Q000187:drug effects; D003453:Cryptococcosis / Q000188:drug therapy / Q000382:microbiology; D056285:Cryptococcus gattii / Q000187:drug effects* / Q000502:physiology; D025141:Drug Resistance, Fungal / Q000187:drug effects* / Q000502:physiology; D017964:Itraconazole / Q000494:pharmacology*; D008168:Lung / Q000382:microbiology; D008264:Macrophages / Q000382:microbiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008826:Microbial Sensitivity Tests / Q000379:methods; D014774:Virulence / Q000187:drug effects* / Q000502:physiology
chemical_list: D000935:Antifungal Agents; D017964:Itraconazole