Mutations in the cyp51A gene and susceptibility to itraconazole in Aspergillus fumigatus serially isolated from a patient with lung aspergilloma
Mutations in the cyp51A gene and susceptibility to itraconazole in Aspergillus fumigatus serially isolated from a patient with lung aspergilloma
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DOI：
10.1093/jac/dkh507
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发表时间：
2005-01-01
影响因子：
5.2
通讯作者：
Wan, Z
中科院分区：
文献类型：
--
作者：
Chen, J;Li, HM;Wan, Z
目的：监测接受肺部曲霉菌感染治疗的患者分离株的伊曲康唑敏感性变化，并将这些变化与基因型/表型改变联系起来。方法：从患者体内连续回收六株烟曲霉分离株。伊曲康唑 MIC 通过 Etest 和 NCCLS 方法测定。监测生长特征和表型。分子分析包括随机扩增多态性 DNA (RAPD) 测定和 cyp51A 基因测序。结果：伊曲康唑对治疗前第一个分离株的 MIC 为 0.25 mg/L；伊曲康唑治疗 6 个月后恢复的第二株分离株的 MIC > 16 mg/L；停止治疗 2 个月后获得的针对第三种分离株的浓度为 0.5 mg/L。恢复伊曲康唑治疗 4-7 个月后获得的针对最后三种分离株的 MIC >16 mg/L。使用四种引物和转录间间隔区 (ITS) 中的相同序列，这 6 个分离株具有相同的 RAPD 测定带模式。因此，这6个分离株很可能是同一株烟曲霉，并且这些分离株在长期伊曲康唑治疗后可能发生了伊曲康唑耐药突变。编码区 cyp51A 基因的测序显示，第二个耐药分离株的细胞色素 P450 甾醇 14-α-脱甲基酶中存在 M220I 突变，最后三个耐药分离株中存在 G54R 突变。一些泵基因（例如MDR3）的表达变化也可能部分与伊曲康唑耐药有关。结论：我们得出结论：烟曲霉在接受该药物治疗的患者中出现了对伊曲康唑的耐药性，这种耐药性可能是由编码伊曲康唑靶酶的基因cyp51A基因突变引起的。
Objectives: To monitor changes in itraconazole susceptibility of isolates from a patient undergoing treatment for pulmonary Aspergillus infection and relate these changes to genotypic/phenotypic alterations.Methods: Six Aspergillus fumigatus isolates were serially recovered from the patient. Itraconazole MICs were determined by Etest and NCCLS methodology. Growth characteristics and phenotype were monitored. Molecular analysis included random amplified polymorphic DNA (RAPD) assay and sequencing of the cyp51A gene.Results: The MIC of itraconazole against the first isolate before treatment was 0.25 mg/L; the MIC against the second isolate, recovered after 6 months of itraconazole therapy, was >16 mg/L; and that against the third isolate, obtained 2 months after discontinuation of the therapy, was 0.5 mg/L. The MIC against the last three isolates, acquired after restoration of itraconazole therapy for 4-7 months, was >16 mg/L. The six isolates shared identical band patterns of RAPD assay using four primers and the same sequence in intertranscribed spacers (ITS). Therefore, the six isolates were likely to be the same strain of A. fumigatus, and mutations involving itraconazole resistance possibly occurred in these isolates after prolonged itraconazole therapy. Sequencing of the cyp51A gene in the coding region revealed a mutation of M220I in cytochrome P450 sterol 14-alpha-demethylase in the second resistant isolate and a mutation of G54R in the last three resistant isolates. Expression changes of some pump genes, such as MDR3, may also, in part, be related to the resistance to itraconazole.Conclusions: We conclude that resistance of A. fumigatus to itraconazole occurred in a patient treated with the drug, and the resistance may result from mutations in the cyp51A gene-the gene encoding the target enzyme for itraconazole.