Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra, Uttar Pradesh, India.
Int J Mycobacteriol. 2020 Jan-Mar;9(1):34-38. doi: 10.4103/ijmy.ijmy_194_19.
Fluoroquinolones (FQs) are being used as second-line agents in the treatment of tuberculosis caused by multidrug-resistant strains. Ofloxacin (OFX) is being tried as a part of modified multidrug therapy regimens for leprosy. A preliminary study was carried out to evaluate the accumulation of FQs - OFX, levofloxacin (LFX), norfloxacin (NFX), and ciprofloxacin (CIF) in Mycobacterium smegmatis.
M. smegmatis were grown in Sauton's medium till log phase, harvested and resuspended in phosphate buffer (0.1 M, pH 7.2, Optical Density (OD) of 0.4-0.5) The suspensions were incubated with OFX, LFX, NFX, and CIF (10 μg/ml) at 37°C. The drugs were estimated in the supernatants using spectrofluorimeteric methods. The experiments were also conducted with the addition of carbonyl cyanide m-chlorophenyl hydrazone (CCCP), a proton motive force inhibitor, at 100 μM, 10 min before and/or immediately after the addition of the drugs.
The time taken to achieve a Steady State Concentration (SSC) of OFX in M. smegmatis was 3 min and the level of accumulation was 102 ng/mg dry weight of the bacilli; with LFX the time for SSC was 5 min and the level of accumulation was 90 ng/mg; in case of NFX the accumulation to SSC was 87 ng/mg in 3 min. CIF accumulation attained a steady state (SSC level of 79 ng/mg) in 4 min. The accumulation kinetics for NFX in M. smegmatis using the spectrofluorimetric method is comparable with radioactive assays. Dose-related accumulation was observed with 10 μg/ml exposure concentrations. The addition of CCCP failed to influence the accumulation of each of these quinolones.
The findings of dose-related accumulation of OFX, LFX NFX, and CIF suggest simple diffusion as the possible mechanism of transport of these drugs.
氟喹诺酮类药物（FQs）被用作治疗耐多药结核分枝杆菌引起的结核病的二线药物。氧氟沙星（OFX）正被尝试作为麻风病改良多药治疗方案的一部分。进行了一项初步研究，以评估氟喹诺酮类药物-OFX、左氧氟沙星（LFX）、诺氟沙星（NFX）和环丙沙星（CIF）在耻垢分枝杆菌中的积累。
耻垢分枝杆菌在 Sauton 培养基中生长至对数期，收获并悬浮在磷酸盐缓冲液（0.1 M，pH 7.2，光密度（OD）为 0.4-0.5）中。将这些悬浮液与 OFX、LFX、NFX 和 CIF（10 μg/ml）在 37°C 下孵育。使用分光荧光计法在上清液中估计药物。实验还在加入 100 μM 的羰基氰化物 m-氯苯腙（CCCP），一种质子动力势抑制剂之前 10 分钟和/或在加入药物后立即进行。
OFX 在耻垢分枝杆菌中达到稳态浓度（SSC）的时间为 3 分钟，积累水平为 102 ng/mg 干重的杆菌；LFX 的 SSC 时间为 5 分钟，积累水平为 90 ng/mg；NFX 的积累到 SSC 为 3 分钟 87 ng/mg。CIF 在 4 分钟内达到稳态（SSC 水平为 79 ng/mg）。用分光荧光法测定耻垢分枝杆菌中 NFX 的积累动力学与放射性测定法相当。观察到 10 μg/ml 暴露浓度下的剂量相关积累。CCCP 的加入未能影响这些喹诺酮类药物的积累。
OFX、LFX、NFX 和 CIF 的剂量相关积累的发现表明，这些药物的转运可能是简单扩散。
