Elie Djenontin, Anne Debourgogne, Bita Mousavi, Laurence Delhaes, Muriel Cornet, Isabel Valsecchi, Makiath Adebo, Jacques Guillot, Françoise Botterel, Eric Dannaoui
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引用次数: 0
Abstract
Background: The resistance of Aspergillus flavus to the azole antifungal drugs is an emerging problem. Mutations in the molecular targets of the azole antifungals - CYP 51 A, B and C - are possible mechanisms of resistance, but data to confirm this hypothesis are scarce. In addition, the behaviour of resistant strains in vitro and in vivo is not yet understood.
Objectives: This study had 3 objectives. The first was to compare the sequences of CYP51 A, B and C in resistant and susceptible strains of A. flavus. The second was to look for the existence of a fitness cost associated with resistance. The third was to evaluate the activity of voriconazole and posaconazole on resistant strains in the Galleria mellonella model.
Methods: The CYP51 A, B and C sequences of seven resistant strains with those of four susceptible strains are compared. Fitness costs were assessed by growing the strains in RPMI medium and testing their virulence in G. mellonella larvae. In addition, G. mellonella larvae infected with strains of A. flavus were treated with voriconazole and posaconazole.
Results: In the CYP51A sequences, we found the A91T, C708T and A1296T nucleotide substitutions only in the resistant strains. The resistant strains showed a fitness cost with reduced in vitro growth and reduced virulence in G. mellonella. In vivo resistance to posaconazole is confirmed in a strain with the highest MIC for this antifungal agent.
Conclusions: These results allow to conclude that some substitutions in CYP51 genes, in particular CYP51A, contribute to resistance to azole drugs in A. flavus. The study of the relationship between drug dosage and treatment duration with resistance and the reduction of fitness costs in resistant strains is a major perspective of this study. This work could help to establish recommendations for the treatment of infections with resistant strains of A. flavus.
期刊介绍：
The journal Mycoses provides an international forum for original papers in English on the pathogenesis, diagnosis, therapy, prophylaxis, and epidemiology of fungal infectious diseases in humans as well as on the biology of pathogenic fungi.
Medical mycology as part of medical microbiology is advancing rapidly. Effective therapeutic strategies are already available in chemotherapy and are being further developed. Their application requires reliable laboratory diagnostic techniques, which, in turn, result from mycological basic research. Opportunistic mycoses vary greatly in their clinical and pathological symptoms, because the underlying disease of a patient at risk decisively determines their symptomatology and progress. The journal Mycoses is therefore of interest to scientists in fundamental mycological research, mycological laboratory diagnosticians and clinicians interested in fungal infections.
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