Unité de Parasitologie-Mycologie, Département de Virologie, Bactériologie-Hygiène, Parasitologie-Mycologie, CHU Henri Mondor, AP-HP, Créteil, France.
UR Dynamyc UPEC, EnvA, ANSES. Faculté de Santé de Créteil, Créteil, France.
Mycoses. 2024 Jul;67(7):e13766. doi: 10.1111/myc.13766.
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.
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.
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.
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.
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.
黄曲霉菌对唑类抗真菌药物的耐药性是一个新出现的问题。唑类抗真菌药物的分子靶标（CYP51A、B 和 C）的突变可能是耐药的机制，但证实这一假设的数据很少。此外，耐药菌株在体外和体内的行为尚不清楚。
本研究有 3 个目的。第一个目的是比较耐药和敏感的黄曲霉菌株中 CYP51A、B 和 C 的序列。第二个目的是寻找与耐药相关的适应度代价。第三个目的是评估伏立康唑和泊沙康唑对黄曲霉菌在大蜡螟模型中的活性。
比较了 7 株耐药株和 4 株敏感株的 CYP51A、B 和 C 序列。通过在 RPMI 培养基中培养菌株并在大蜡螟幼虫中测试其毒力来评估适应度代价。此外，还在感染黄曲霉菌株的大蜡螟幼虫中用伏立康唑和泊沙康唑进行了治疗。
在 CYP51A 序列中，我们仅在耐药株中发现了 A91T、C708T 和 A1296T 核苷酸取代。耐药株的体外生长速度较慢，在大蜡螟中的毒力降低，表现出适应度代价。在一种对这种抗真菌药物 MIC 最高的菌株中，体内对泊沙康唑的耐药性得到了证实。
这些结果表明，CYP51 基因中的某些突变，特别是 CYP51A，有助于黄曲霉菌对唑类药物的耐药性。研究药物剂量与耐药性和耐药菌株适应度代价降低之间的关系是本研究的一个主要方向。这项工作可以帮助制定治疗耐药黄曲霉菌感染的建议。
