大环内酯类和氟喹诺酮类药物对细胞内嗜肺军团菌的作用

Activity of macrolides and fluoroquinolones against intracellular Legionella pneumophila

目的评估大环内酯类和氟喹诺酮类药物对巨噬细胞内嗜肺军团菌的作用。方法采用琼脂稀释法测量大环内酯类和氟喹诺酮类药物对20株嗜肺军团菌血清1型（三．pneumophilaserogroup Ⅰ，Lp-1）的MIC值。加入佛波酯诱导人类单核细胞系THP-1分化成巨噬细胞样细胞。将Lp-1与分化的THP-1细胞共培养，细胞吞噬细菌后，加入红霉素、阿奇霉素、左氧氟沙星及莫西沙星4种抗菌药物，在l×MIC、4×MIC、8×MIC浓度时培养24h，平板计数法双份计数细胞内存活的军团菌数。结果以细菌抑制率表示，不同抗菌药物作用的差别采用Mann-WhitneyU检验分析。结果4种抗菌药物在1×MIC、4×MIC、8×MIC浓度时作用24h后的细菌抑制率分别为：红霉素：（50．18±27．29）％、（79．48±20．08）％及（91．46±8．70）％；阿奇霉素：（66．77±26．18）％、（91．73±8．72）％及（97．10±3．37）％；左氧氟沙星：（99．84±0．25）％、（99．99±0．02）％及（99．99±0．01）％；莫西沙星：（99．90±0．10）％、（99．99±0．03）％及（99．99±0．03）％。氟喹诺酮类药物在1×MIC、4×MIC、8×MIC时对细胞内Lp-l的抑制率高于大环内酯类药物（u值分别为1．0、2．0和5．0，均P〈0．05），左氧氟沙星和莫西沙星在上述3个浓度时对Lp-l的抑制率差异无统计学意义（u值分别为190、183和217，均P〉0．05），阿奇霉素对细胞内Lp-1的抑制率高于红霉素（u值分别为132、125和128，均P〈0．05）。结论氟喹诺酮类药物细胞内抗军团菌的作用优于大环内酯类药物，左氧氟沙星和莫西沙星细胞内抗军团菌的作用相似，阿奇霉素细胞内抗军团菌的作用优于红霉素。

Objective To evaluate the activity of macrolides and fluoroquinolones against Legionella pneumophila by intracellular susceptibility testing. Methods Minimum inhibitory concentration（MIC） was determined by standard agar dilution test according to the CLSI. For intracellular assays, legionella pneumonia was used to infect human monocytic cell line THP-1. Erythromycin, azithromycin, levofloxacin and moxifloxacin at 1ХMIC, 4Х MIC, 8 Х MIC were added following phagocytosis. Number of viable bacteria was enumerated at 24 h on BCYE （buffered charcoal yeast extract） agar in duplicates using standard plate count method. The result was expressed as percentage inhibition. Mann-Whitney U test was used to determine the significant differences in mean percentage inhibition between agents. Results Percentage inhibition at 24 h were as follows： Erythromycin 1 x MIC （50. 18±27.29）%, 4 x MIC （79.48 ±20.08） %, 8 x MIC （91.46 ± 8.70） % ; Azithromycin 1 x MIC （66.77± 26. 18） %, 4 x MIC （91.73 ± 8. 72）%, 8 x MIC （97. 10± 3. 37）% ; Levofloxacin 1 xMIC （99. 84 ± 0. 25）%, 4 x MIC （99. 99± 0.02）%, 8 xMIC （99.99 ±0.01）%; Moxifloxacin 1xMIC （99.90±0.10）%, 4xMIC （99.99± 0. 03）%, 8 x M1C （99. 99 ±0. 03 ）% . The fluoroquinolones showed greater inhibitory activity than macrolides against legionella pneumophila（ u = 1.0,2.0,5.0, P 〈 0. 05 ）. Levofloxacin and moxifloxacin bad the same iutracellular activity against legionella pneumophila （ u = 190, 183,217 ,P 〉 0.05 ）. Azitbromycin was more effective than erythromycin in inhibiting intracellular legionella pneumophila （ u = 132,125,128, P 〈 0. 05 ）. Conclusions The fluoroquinolones were more active than macrolides against legionellapneumophila. The intracellular activity of levofloxacin against legionella pneumophila appeared to be similar to moxifloxaein. Azithromycin was demonstrated to have superior activity against legionella pneumophila compared with erythromycin.