Chopra I
J Gen Microbiol. 1976 Oct;96(2):229-38. doi: 10.1099/00221287-96-2-229.
The biochemical mechanisms of resistance to fusidic acid in Staphylococcus aureus were investigated. Organisms possessing plasmid genes for resistance showed a high basal level of resistance, but could be induced to higher levels after pre-incubation with fusidic acid. This induction occurred rapidly and probably did not depend on gene dosage effects. Mutants resistant to fusidic acid, obtained from plasmid-negative cultures, expressed resistance constitutively. Protein synthesis in cell-free extracts from staphylococci with plasmid-mediated resistance to fusidic acid was as sensitive to fusidic acid as was synthesis in preparations from sensitive organisms; whereas protein synthesis in preparations from a spontaneous fusidic acid resistant mutant was resistant to the antibiotic. None of the resistant strains caused detectable inactivation of fusidic acid and no new derivative of fusidic acid was found in culture extracts of plasmid-possessing organisms grown in the presence of radioactive antibiotic. Expression of plasmid-mediated resistance to fusidic acid was associated with a decrease in the molar ratio of phosphatidylglycerol to lysylphosphatidylglycerol, but the cardiolipin content remained constant.
对金黄色葡萄球菌中对夫西地酸耐药的生化机制进行了研究。携带耐药质粒基因的菌株显示出较高的基础耐药水平，但在用夫西地酸预孵育后可被诱导至更高水平。这种诱导迅速发生，可能不依赖于基因剂量效应。从质粒阴性培养物中获得的对夫西地酸耐药的突变体组成性地表达耐药性。来自具有质粒介导的对夫西地酸耐药性的葡萄球菌的无细胞提取物中的蛋白质合成对夫西地酸的敏感性与敏感菌株制备物中的合成一样；而来自自发的夫西地酸耐药突变体的制备物中的蛋白质合成对抗生素具有抗性。没有一个耐药菌株导致可检测到的夫西地酸失活，并且在存在放射性抗生素的情况下生长的携带质粒的生物体的培养提取物中未发现夫西地酸的新衍生物。质粒介导的对夫西地酸耐药性的表达与磷脂酰甘油与赖氨酰磷脂酰甘油的摩尔比降低有关，但心磷脂含量保持不变。
