Discrepancy between Uptake and Intracellular Activity of Moxifloxacin in a Staphylococcus aureus-Human THP-1 Monocytic Cell Model
Discrepancy between Uptake and Intracellular Activity of Moxifloxacin in a Staphylococcus aureus-Human THP-1 Monocytic Cell Model
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DOI：
10.1128/aac.46.2.288-293.2002
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发表时间：
2002-02
影响因子：
4.9
通讯作者：
Delphine Paillard;J. Grellet;V. Dubois;M. Saux;C. Quentin
中科院分区：
文献类型：
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作者：
Delphine Paillard;J. Grellet;V. Dubois;M. Saux;C. Quentin
摘要：通过5小时的实验，研究了THP-1对莫西沙星的吸收与其对金黄色葡萄球菌ATCC 25923（一种敏感对照菌株，莫西沙星的最小抑菌浓度为0.1 mg/l）的抑菌活性之间的关系。以0.2 ~ 32 mg/l的浓度加入培养基，采用高效液相色谱法测定药物的吸收情况。莫西沙星的细胞外浓度比达到平衡时，未感染细胞为4.36±0.39，感染细胞为6.25±0.41。莫西沙星以0.06 ~ 8 mg/l的浓度加入细胞外液，通过活菌计数测定其胞内活性。当浓度≤0.2 mg/l时，药物仅抑制细胞内细菌的生长，而当浓度≥0.5 mg/l时，药物使细菌接种量减少不到1 log10单位，在3 ~ 4 h时效果最大，在5 h时，存活细菌重新生长到原始水平的80 ~ 120%。相反，当使用相似接种量（107 CFU/ml）的muller - hinton肉汤测定杀伤曲线时，莫西沙星浓度≥0.2 mg/l时，接种量在3 ~ 4 h减少至少3 log10单位，24 h存活率≤0.1%。持久菌株表现出与金黄色葡萄球菌ATCC 25923相同的氟喹诺酮类药物敏感性。我们的数据表明，治疗性细胞外浓度的莫西沙星在感染的THP-1细胞中积累了大约6倍，并在细胞内保持活性，但活性明显低于体外条件下。
ABSTRACT The correlation between uptake of moxifloxacin by THP-1, a continuous line of monocytic cells devoid of intrinsic bactericidal properties, and its activity against Staphylococcus aureus ATCC 25923, a susceptible reference strain (MIC and minimal bactericidal concentration of moxifloxacin, 0.1 mg/liter), was studied in a 5-h assay. The uptake of the drug, added to the culture medium at 0.2 to 32 mg/liter, was evaluated by high-performance liquid chromatography. The ratio of the cellular to extracellular concentration of moxifloxacin reached, at equilibrium, 4.36 ± 0.39 in uninfected cells and 6.25 ± 0.41 in infected cells. The intracellular activity of moxifloxacin, introduced into the extracellular fluid at 0.06 to 8 mg/liter, was determined by the enumeration of viable bacteria. At concentrations ≤0.2 mg/liter, the drug inhibited only the intracellular bacterial growth, while at concentrations ≥0.5 mg/liter, it decreased the bacterial inoculum by less than 1 log10 unit, with a maximum effect at 3 to 4 h, followed by regrowth of surviving bacteria to 80 to 120% of the original level at 5 h. In contrast, when killing curves were determined by using Mueller-Hinton broth with a similar inoculum (107 CFU/ml), moxifloxacin at concentrations ≥0.2 mg/liter reduced the inoculum by at least 3 log10 units at 3 to 4 h, leaving ≤0.1% survival at 24 h. Persisters exhibited a fluoroquinolone susceptibility identical to that of S. aureus ATCC 25923. Our data indicate that moxifloxacin at therapeutic extracellular concentrations accumulates approximately sixfold in infected THP-1 cells and remains active intracellularly, but significantly less active than under in vitro conditions.