Pharmacologie Cellulaire et Moléculaire, Louvain Drug Research Institute, Université Catholique de Louvain, Brussels, Belgium.
Antimicrob Agents Chemother. 2013 May;57(5):2310-8. doi: 10.1128/AAC.02609-12. Epub 2013 Mar 11.
Pseudomonas aeruginosa invades epithelial and phagocytic cells, which may play an important role in the persistence of infection. We have developed a 24-h model of THP-1 monocyte infection with P. aeruginosa PAO1 in which bacteria are seen multiplying in vacuoles by electron microscopy. The model has been used to quantitatively assess antibiotic activity against intracellular and extracellular bacteria by using a pharmacodynamic approach (concentration-dependent experiments over a wide range of extracellular concentrations to calculate bacteriostatic concentrations [Cs] and maximal relative efficacies [Emax]; Hill-Langmuir equation). Using 16 antipseudomonal antibiotics (three aminoglycosides, nine β-lactams, three fluoroquinolones, and colistin), dose-response curves were found to be undistinguishable for antibiotics of the same pharmacological class if data were expressed as a function of the corresponding MICs. Extracellularly, all of the antibiotics reached a bacteriostatic effect at their MIC, and their Emax exceeded the limit of detection (-4.5 log(10) CFU compared to the initial inoculum). Intracellularly, Cs values remained unchanged for β-lactams, fluoroquinolones, and colistin but were approximately 10 times higher for aminoglycosides, whereas Emax values were markedly reduced (less negative), reaching -3 log(10) CFU for fluoroquinolones and only -1 to -1.5 log(10) CFU for all other antibiotics. The decrease in intracellular aminoglycoside potency (higher Cs) can be ascribed to the acid pH to which bacteria are exposed in vacuoles. The decrease in the Emax may reflect a reversible alteration of bacterial responsiveness to antibiotics in the intracellular milieu. The model may prove useful for comparison of antipseudomonal antibiotics to reduce the risk of persistence or relapse of pseudomonal infections.
铜绿假单胞菌可入侵上皮细胞和吞噬细胞，这可能在感染持续存在中发挥重要作用。我们建立了一个 24 小时 THP-1 单核细胞感染铜绿假单胞菌 PAO1 的模型，在该模型中，电子显微镜下可见细菌在空泡内繁殖。该模型已被用于通过药效学方法（在广泛的细胞外浓度范围内进行浓度依赖性实验以计算抑菌浓度 [Cs] 和最大相对功效 [Emax]；Hill-Langmuir 方程）定量评估抗生素对细胞内和细胞外细菌的活性。使用 16 种抗假单胞菌抗生素（三种氨基糖苷类、九种β-内酰胺类、三种氟喹诺酮类和多粘菌素），如果数据以相应的 MIC 为函数表示，则发现同一种药理类别的抗生素的剂量反应曲线没有区别。在细胞外，所有抗生素在其 MIC 时均达到抑菌作用，其 Emax 超过检测下限（与初始接种物相比，减少了 -4.5 log(10) CFU）。在细胞内，β-内酰胺类、氟喹诺酮类和多粘菌素的 Cs 值保持不变，但氨基糖苷类的 Cs 值约增加了 10 倍，而 Emax 值明显降低（负值较小），对于氟喹诺酮类，Emax 值达到 -3 log(10) CFU，而对于所有其他抗生素，Emax 值仅达到 -1 至 -1.5 log(10) CFU。细胞内氨基糖苷类药物效力降低（较高的 Cs）可归因于细菌在空泡中暴露的酸性 pH 值。Emax 的降低可能反映了细菌对细胞内环境中抗生素的反应性的可逆改变。该模型可能有助于比较抗假单胞菌抗生素，以降低假单胞菌感染持续或复发的风险。
