DNA gyrase and quinolone resistance in tuberculosis

这个项目的目标是了解喹诺酮类药物如何在a分枝杆菌中发挥作用，并找到方法来 保护化合物免受抗药性的发展。先前的研究表明，这种结构 氟喹诺酮类药物的C-8位修饰提高了抗菌活性，特别是在 氟喹诺酮耐药突变株。这一特征，加上氟喹诺酮结构的其他变体，将是 检验以探索这一假设，即致死活性部分是由旋转酶亚基的解离引起的 附着在断裂的DNA上。因为旋转酶亚基的解离在没有 蛋白质合成，这项工作可能会揭示出改善对不生长的细菌的作用的方法。要定义 低浓度氟喹诺酮类药物如何影响耐药突变株的产生 通过在低药物浓度下选择性生长获得的结核分枝杆菌 检查他们是否有能力增加随后的旋转酶突变体选择性地 富足了。这部分研究预计将影响氟喹诺酮类药物的给药策略。在病人身上， 结核分枝杆菌很容易产生耐药性，因此抗结核药物被作为联合用药使用。 因此，新的氟喹诺酮类药物的致死活性将与 用于识别不太可能具有内在干扰的化合物组合的传统试剂 活动。传统药物也将与C-8-甲氧基氟喹诺酮类药物在动态中结合 体外模型，以考察药效失配对耐药性发展的影响。这些 该计划的两个方面将有助于优化新氟喹诺酮类药物的使用。为临床提供一种 在这项工作的背景下，将检查来自纽约市的分离株对氟喹诺酮类药物的敏感性。 将上世纪90年代初获得的菌株与最近获得的菌株进行比较，将表明 敏感度正在丧失。从这些体外研究中得出的原则可能普遍适用于 氟喹诺酮类药物治疗的细菌感染；有关耐药性的想法也可能 扩展到其他化合物，在这些化合物中，从头开始的抗菌素耐药性是逐步发展的 举止。

The goals of this program are to understand how the quinolones act in mycobacteri a and to discover ways to protect the compounds from the development of resistance. Previous work showed that structure modifications at the C-8 position of fluoroquinolones increase antibacterial activity, particularly with fluoroquinolone-resistant mutants. This feature, plus other variations in fluoroquinolone structure, will be examined to explore the hypothesis that lethal activity arises in part from the dissociation of gyrase subunits attached to cleaved DNA. Since gyrase subunit dissociation is assayed as lethal activity in the absence of protein synthesis, this work may reveal ways to improve action against nongrowing bacteria. To define how low fluoroquinolone concentrations affect the development of resistance, nongyrase resistance mutants of Mycobacterium tuberculosis, obtained through selective growth at low drug concentration, will be examined for their ability to increase the frequency at which subsequent gyrase mutants are selectively enriched. This portion of the study is expected to influence fluoroquinolone dosing strategies. In patients, M. tuberculosis develops resistance so readily that anti-tuberculosis agents are administered as combination therapies; consequently, the lethal activity of new fluoroquinolones will be examined in combination with traditional agents to identify combinations of compounds that are unlikely to have intrinsic interfering activities. Traditional agents will also be combined with C-8-methoxy fluoroquinolones in a dynamic in vitro model to examine the effect of pharmacodynamic mismatch on the development of resistance. These two aspects of the program will help optimize the use of new fluoroquinolones. To provide a clinical context for the work, isolates from New York City will be examined for susceptibility to fluoroquinolones. Comparison of isolates obtained in the early 1990s with those obtained recently will indicate whether susceptibility is being lost. Principles emerging from these in vitro studies may be generally applicable to bacterial infections for which fluoroquinolone treatment is indicated; ideas concerning resistance may also extend to other compounds in which de novo antimicrobial resistance develops in a gradual, stepwise manner.