Genomic Research Laboratory, University Hospitals of Geneva and University of Geneva, Geneva, Switzerland.
J Antimicrob Chemother. 2011 Aug;66(8):1696-711. doi: 10.1093/jac/dkr195. Epub 2011 May 28.
The development of daptomycin resistance in Staphylococcus aureus is associated with clinical treatment failures. The mechanism(s) of such resistance have not been clearly defined.
We studied an isogenic daptomycin-susceptible (DAP(S)) and daptomycin-resistant (DAP(R)) S. aureus strain pair (616; 701) from a patient with relapsing endocarditis during daptomycin treatment, using comparative transcriptomic and proteomic techniques.
Minor differences in the genome content were found between strains by DNA hybridization. Transcriptomic analyses identified a number of genes differentially expressed in important functional categories: cell division; metabolism of bacterial envelopes; and global regulation. Of note, the DAP(R) isolate exhibited reduced expression of the major cell wall autolysis gene coincident with the up-regulation of genes involved in cell wall teichoic acid production. Using quantitative (q)RT-PCR on the gene cadre putatively involved in cationic peptide resistance, we formulated a putative regulatory network compatible with microarray data sets, mainly implicating bacterial envelopes. Of interest, qRT-PCR of this same gene cadre from two distinct isogenic DAP(S)/DAP(R) clinical strain pairs revealed evidence of other strain-dependent networks operative in the DAP(R) phenotype. Comparative proteomics of 616 versus 701 revealed a differential abundance of proteins in various functional categories, including cell wall-associated targets and biofilm formation proteins. Phenotypically, strains 616 and 701 showed major differences in their ability to develop bacterial biofilms in the presence of the antibacterial lipid, oleic acid.
Compatible with previous in vitro observations, in vivo-acquired DAP(R) in S. aureus is a complex, multistep phenomenon involving: (i) strain-dependent phenotypes; (ii) transcriptome adaptation; and (iii) modification of the lipid and protein contents of cellular envelopes.
金黄色葡萄球菌对达托霉素的耐药性的发展与临床治疗失败有关。其耐药机制尚未明确。
我们使用比较转录组学和蛋白质组学技术，研究了来自一名复发心内膜炎患者在达托霉素治疗期间的一对同源性达托霉素敏感（DAP(S)）和达托霉素耐药（DAP(R)）金黄色葡萄球菌菌株（616；701）。
通过 DNA 杂交发现，两种菌株的基因组含量存在微小差异。转录组分析确定了许多在重要功能类别中差异表达的基因：细胞分裂；细菌包膜代谢；和全局调控。值得注意的是，DAP(R)分离株表现出主要细胞壁自溶基因表达降低，同时与细胞壁磷壁酸产生相关的基因上调。使用定量（q）RT-PCR 对推定参与阳离子肽耐药的基因进行检测，我们构建了一个与微阵列数据集兼容的假定调控网络，主要涉及细菌包膜。有趣的是，对两个不同同源性 DAP(S)/DAP(R)临床分离株的同一基因进行 qRT-PCR 分析表明，在 DAP(R)表型中存在其他依赖菌株的网络。616 与 701 的比较蛋白质组学揭示了各种功能类别中蛋白质的差异丰度，包括细胞壁相关靶标和生物膜形成蛋白。表型上，菌株 616 和 701 在存在抗菌脂质油酸的情况下，细菌生物膜形成能力存在显著差异。
与之前的体外观察结果一致，金黄色葡萄球菌中体内获得的 DAP(R)是一个复杂的多步骤现象，涉及：（i）菌株依赖性表型；（ii）转录组适应；和（iii）细胞包膜中脂质和蛋白质含量的修饰。
