安妥沙星纸片扩散法外抗菌活性测定折点初步研究

目的：确定安妥沙星对葡萄球菌属、肠杆菌科、非发酵菌及嗜血杆菌属的纸片扩散法体外抗菌活性测定折点。方法：采用标准琼脂二倍稀释法与纸片扩散法（5μg和10μg）测定安妥沙星对临床常见致病菌的敏感性，并与临床常用的氟喹诺酮类药物相比较分析，结合人体药代动力学参数，利用MIC与抑菌圈直径散点图，初步确定安妥沙星纸片扩散法对常见细菌的折点。结果：安妥沙星的体外抗菌作用与左氧氟沙星接近且相关性最好，根据安妥沙星琼脂稀释法体外抗菌活性测定的临界浓度（嗜血杆菌敏感临界浓度为≤1mg／L，其他细菌敏感、中介与耐药临界浓度分别为≤2、4、≥8mg／L），利用MIC与抑菌圈直径散点图初步确定安妥沙星（10扯g）纸片对嗜血杆菌抑菌圈直径≥21mm为敏感，其它菌种耐药、中介与敏感的抑菌圈直径分别为≤14mm、15～17mm和≥18mm。标准菌株质控范围分别为大肠埃希菌ATCC2592224～31mm，铜绿假单胞菌ATCC2785322～26mm，金黄色葡萄球菌ATCC2592322～28mm。结论：通过体外抗菌活性比较，利用MIC与抑菌圈直径散点图，初步确定了安妥沙星纸片扩散法体外抗菌活性测定对常见细菌的折点，供临床应用参考与验证。

Primary study of antofloxaicn breakpoints with disc-diffusion sensitivity test

AIM： To determine the break-points of Antofloxacin sensitivity with disc-diffusion test for staphylococci, enterobacteriaceae, non-fermenter and hemophili in primary. METHODS： The in vitro antibacterial activity of Antofloxacin and other comparators was detected with standard agar dilution and disc-diffusion （Antofloxaein 5μg and 10 μg discs） methods. Referring to the association of in vitro antibacterial activity of different fluoroquinolones and pharmacokinetics property of the investigated agent, the breakpoints of Antofloxacin were determined with scattergram between MIC and bacterial inhibitory zone. RESULTS： The in vitro antibacterial activity of Antofloxacin against clinical isolates shown better association with those of levofloxacin. Referring to the proposed sensitive breakpoints of Antofloxaein with agardilution method （hemophili being recommended as 41 mg/L for sensitive; the sensitive, intermediate and resistant breakpoints against other pathogens being ≤2, 4,≥8 mg/L, respectively）, the bacterial inhibitory zone breakpoints with disc-diffusion method （10 μg disc） were set as 921 mm against hemophili for sensitive and ≤14 mm, 15--17 mm, ≥18 mm against the other germs for resistant, intermediate and sensitive. The quality control inhibitory zones against referring strains were 24-31mm for Escherichia coli ATCC25922, 22--26 mm for Pseudomonas aeruginosa ATCC27853 and 22-28mm for Staphylococcus aureus ATCC25923, respectively. CONCLUSION： Referring to the in vitro antibacterial activity and making use of the scattergram between MIC and inhibition zone of Antofloxacin, the breakpoints for in vitro sensitive test with disc-diffusion method were established in primary and recommended for clinical practice and future review.