氟喹诺酮类和大环内酯类药物对解脲脲原体的抗菌活性分析

In Vitro Antibacterial Activities of Fluoroquinolones and Macrolides Against Ureaplasma urealyticumin

目的研究解脲脲原体(Uu)对氟喹诺酮类和大环内酯类药物的敏感性,及不同pH值对大环内酯类药物在体外抗Uu最低抑菌浓度(MIC)的影响。方法采用微量肉汤法检测了7种抗菌药物对72株Uu的MIC,及在pH值为6.0、6.5和6.9时,4种大环内脂药物抗Uu的MIC50。结果72株Uu对左氧氟沙星、红霉素和罗红霉素耐药率分别为4.2%、15.3%和2.7%,未发现对加替沙星、司帕沙星、阿奇霉素和交沙霉素的耐药。司帕沙星和交沙霉素抗Uu活性最强,而红霉素和罗红霉素的抗Uu活性最差。当pH值6.0升到6.9时,红霉素的MIC50下降8倍,而罗红霉素、阿奇霉素和交沙霉素MIC50分别下降4倍、16倍、8倍。结论Uu对左氧氟沙星、红霉素和罗红霉素存在不同程度的耐药。左氧氟沙星、加替沙星、司帕沙星抗Uu活性依次增强,大环内脂类药物抗Uu活性由强到弱分别是交沙霉素(16环)、阿奇霉素(15环)、红霉素和罗红霉素(14环)。随着pH值在6.0～6.9升高时,大环内脂药物对Uu的MIC随着pH的升高而减少。

Objective To determine the susceptibilities of clinical Ureaplasma urealyticum（Uu）isolates to fluoroquinolo- nes and macrolides, and to explore the effects of medium pH on MIC of macrolides against Uu in vitro. Methods Seven antimicrobial MICs against 72 strains of Uu, and MICs0 of four macrolides in pH at 6.0, 6.5 and 6.9 were assessed by broth microdilution method. Results The resistant rates of 72 strains of Uu were： levofloxacin 4.2%, erythromycin 15.3 %, rox- ithromycin 2.7%, while jatifloxacin, sparfloxacin, azithromycin, and josamycin showed no resistance to them. Among the seven agents, josamycin and sparfloxacin were the most active. When pH increased from 6.0 to 6.9, the MIC50 of erythromycin, roxithromycin, azithromycin and josamycin decreased significantly by 8, 4, 16and 8 respectively. Conclusions The degree of resistance rate of Uu to levofloxacin, rythromycin and roxithromycin varied. New fluoroquinolones such as sparfloxacin and jatifloxacin show greater activity against Uu than levofloxacin; the 16- membered macrolides such as josamycin are more active against Uu than 15 - membered macrolides （azithromycin） and 14 - membered macrolides （erythromycin and roxithromycin）. Moreover; the results suggest that the MICs of macrolides to Uu decrease significantly as the culture medium pH increases from 6.0 to 6.9.