Burns J L, Smith A L
Antimicrob Agents Chemother. 1987 May;31(5):686-90. doi: 10.1128/AAC.31.5.686.
The mechanism of chloramphenicol transport into susceptible strains of Haemophilus influenzae cells has not been reported previously. We examined apparent uptake of chloramphenicol by bacterial cells by using high-pressure liquid chromatography to quantitate drug disappearance from liquid media. Cell-associated chloramphenicol concentration is 1,000-fold greater than the extracellular drug concentration. Under incubation conditions associated with chloramphenicol disappearance from media, cellular protein synthesis was inhibited; however, if accumulation was inhibited, protein synthesis occurred in the presence of the drug. Chloramphenicol uptake appeared saturable (Km = 0.96 mM, Vmax = 0.9 mumol/min per mg of protein) and energy dependent: disappearance from media was markedly decreased by 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone, compounds which disrupt the proton motive force. Uptake occurred only in median which can support growth and was dependent upon temperature and pH. Drug accumulation was minimally affected by inhibitors of electron transport or by gentamicin and puromycin, both inhibitors of protein synthesis. The rate of disappearance was inhibited by SCH24893, a fluorinated chloramphenicol analog which also inhibits protein synthesis. We conclude that chloramphenicol accumulation by H. influenzae occurs by energy-dependent transport.
氯霉素转运至流感嗜血杆菌易感菌株细胞内的机制此前尚未见报道。我们通过高压液相色谱法定量测定液体培养基中药物的消失情况，来检测细菌细胞对氯霉素的表观摄取。细胞相关氯霉素浓度比细胞外药物浓度高1000倍。在与培养基中氯霉素消失相关的孵育条件下，细胞蛋白质合成受到抑制；然而，如果摄取被抑制，在药物存在的情况下蛋白质合成仍会发生。氯霉素摄取表现出饱和性（Km = 0.96 mM，Vmax = 0.9 μmol/分钟每毫克蛋白质）且依赖能量：2,4-二硝基苯酚和羰基氰化物间氯苯腙（这两种化合物会破坏质子动力）可使培养基中药物的消失显著减少。摄取仅发生在能支持生长的培养基中，且依赖于温度和pH值。电子传递抑制剂或蛋白质合成抑制剂庆大霉素和嘌呤霉素对药物积累的影响最小。SCH2,4893（一种也能抑制蛋白质合成的氟化氯霉素类似物）可抑制药物消失速率。我们得出结论，流感嗜血杆菌积累氯霉素是通过能量依赖型转运实现的。
