Prevalence of molecular mechanisms of resistance to azole antifungal agents in Candida albicans strains displaying high-level fluconazole resistance isolated from human immunodeficiency virus-infected patients
Prevalence of molecular mechanisms of resistance to azole antifungal agents in Candida albicans strains displaying high-level fluconazole resistance isolated from human immunodeficiency virus-infected patients
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DOI：
10.1128/aac.45.10.2676-2684.2001
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发表时间：
2001-10-01
影响因子：
4.9
通讯作者：
Patterson, TF
中科院分区：
文献类型：
--
作者：
Perea, S;López-Ribot, JL;Patterson, TF
白念珠菌耐药的分子机制，包括靶酶的改变和药物外排增加，已经被描述，但耐药机制的流行病学尚未建立。我们研究了从人类免疫缺陷病毒(HM感染口咽念珠菌病患者)中分离出的对氟康唑高度耐药(MICs，大于或等于mUg/ml)的白色念珠菌对唑类药物耐药的分子机制。在配对的敏感和耐药分离株中，监测了与唑类耐药有关的羊毛甾醇14α-脱甲基酶(ERG11)和外排转运蛋白(MDR)和CDR基因的表达水平。此外，通过聚合酶链式反应扩增了ERG11基因，并测定了其核苷酸序列，以检测可能影响与唑类化合物亲和力的点突变。分析证实了氮唑耐药的多因素性质和这些耐药机制在表现为直接氟康唑耐药的白色念珠菌临床分离株中的普遍存在，在所有耐药株中发现了编码外排泵基因的优势表达，在所有耐药菌株中发现了85%的基因过度表达。在65%和35%的分离株中分别检测到靶酶的变化，包括功能性氨基酸替换和编码该酶的基因的过度表达。总体而言，在表现出高水平氟康唑耐药的菌株中，75%的菌株合并了多种耐药机制。这些结果可能有助于开发新的策略来克服耐药性问题，以及针对这种情况的新治疗方法。
Molecular mechanisms of azole resistance in Candida albicans, including alterations in the target enzyme and increased efflux of drug, have been described, but the epidemiology of the resistance mechanisms has not been established. We have investigated the molecular mechanisms of resistance to azoles in C albicans strains displaying high-level fluconazole resistance (MICs, greater than or equal to 64 mug/ml) isolated from human immunodeficiency virus (HM-infected patients with oropharyngeal candidiasis. The levels of expression of genes encoding lanosterol 14 alpha -demethylase (ERG11) and efflux transporters (MDR) and CDR) implicated in azole resistance were monitored in matched sets of susceptible and resistant isolates. In addition, ERG11 genes were amplified by PCR, and their nucleotide sequences were determined in order to detect point mutations with a possible effect in the affinity for azoles. The analysis confirmed the multifactorial nature of azole resistance and the prevalence of these mechanisms of resistance in C. albicans clinical isolates exhibiting frank fluconazole resistance, with a predominance of overexpression of genes encoding efflux pumps, detected in 85% of all resistant isolates, being found. Alterations in the target enzyme, including functional amino acid substitutions and overexpression of the gene that encodes the enzyme, were detected in 65 and 35% of the isolates, respectively. Overall, multiple mechanisms of resistance were combined in 75% of the isolates displaying high-level fluconazole resistance. These results may help in the development of new strategies to overcome the problem of resistance as well as new treatments for this condition.