丁香挥发油联合喹诺酮类抗生素抗耐甲氧西林金黄色葡萄球菌作用研究

目的 探究丁香挥发油的耐药性和丁香挥发油联合喹诺酮类抗生素抗耐甲氧西林金黄色葡萄球菌（MRSA）的体外活性，为后续丁香挥发油联合抗生素治疗MRSA感染提供科学依据。方法 采用微量稀释法分别测定丁香挥发油、4种喹诺酮类抗生素（莫西沙星、左氧氟沙星、环丙沙星、诺氟沙星）的最小抑菌浓度（MIC）；棋盘稀释法测定丁香挥发油与4种喹诺酮类抗生素联用的部分抑菌浓度（FIC）指数；生长曲线法分析丁香挥发油联合4种喹诺酮类抗生素对MRSA的抑制作用；通过耐药性诱导实验，分析丁香挥发油对MRSA标准株ATCC33591耐药诱导30代后的MIC变化，分析丁香挥发油的耐药性。结果 耐药性分析发现，MRSA临床分离株对莫西沙星的耐药率（88.57%）最高，其次为环丙沙星和左氧氟沙星（77.14%），耐药率相对最低的为诺氟沙星（74.29%）。FIC指数分析显示，丁香挥发油分别与莫西沙星、左氧氟沙星、环丙沙星和诺氟沙星联用呈现不同程度的相互作用，其中协同作用分别为42.86%、37.15%、34.28%、34.28%，相加作用分别为28.57%、25.71%、22.86%、42.86%，无关作用分别为28.57%、20.00%、42.86%、22.86%，与左氧氟沙星联合使用时17.14%实验菌株呈拮抗作用。生长曲线结果显示，丁香挥发油与喹诺酮类抗生素联用对MRSA有明显的协同抑制作用。诱导耐药实验结果显示，亚抑菌浓度的丁香挥发油连续诱导MRSA菌株30代后，MIC无变化；而相同条件下环丙沙星的MIC升高至原来的16倍，说明丁香挥发油不易产生耐药。结论 丁香挥发油不易产生耐药性；与喹诺酮类抗生素联用时呈现不同的作用，多数MRSA菌株呈协同和相加作用，可降低临床喹诺酮类抗生素抗MRSA感染的用量。

Effect of clove oil combined with quinolones antibiotics on methicillin-resistant Staphylococcus aureus

Objective To investigate the anti-methicillin-resistant Staphylococcus aureus (MRSA) activity of clove oil combined with quinolones antibiotics in vitro, and provide scientific evidences for the treatment of MRSA infection by clove oil combined with quinolones antibiotics. Methods Minimal inhibitory concentrations (MICs) of clove oil and four quinolones antibiotics (moxifloxacin, levofloxacin, ciprofloxacin and norfloxacin) were determined by microdilution method; Fractional inhibitory concentration (FIC) indexes of clove oil combined with four quinolones antibiotics were determined by chessboard dilution method; Inhibition effect of MRSA by clove oil combined with four quinolones antibiotics was analyzed by growth curve method. MIC changes were analyzed when MRSA standard strain ATCC33591 was induced 30 generations with clove oil. Results A total of 35 strains of MRSA isolated from clinical patients showed that the highest resistance rate was moxifloxacin (88.57%), followed by ciprofloxacin and levofloxacin (77.14%), and the lowest resistance rate was norfloxacin (74.29%). The results of FIC index analysis showed that the different thesynergistic action effects of clove oil with moxifloxacin, levofloxacin, ciprofloxacin and ornorfloxacin, were 42.86%, 37.15%, 34.28% and 34.28%, respectively; The additive effects of which were 28.57%, 25.71%, 22.86% and 42.86%, respectively; The unrelated effects of that were 28.57%, 20.00%, 42.86% and 22.86%, respectively. Among them, there was partial antagonism in experimental strains when combined with levofloxacin, accounting for 17.14%. The growth curve showed that the combination of clove oil and quinolone antibiotics had a significant synergistic inhibition on MRSA. The results of induced drug resistance test showed that MIC did not change after 30 generations of continuous induction with the clove oil, but increased to 16 times of that of ciprofloxacin under the same condition, which indicated that the clove oil was not easy to make MRSA resistant. Conclusion Clove oil is not easy to produce drug resistance. They showed different interactions on each other when clove oil combined with quinolones antibiotics, and most strains of MRSA isolated from clinical patients had obvious synergistic and additive inhibition effect. The dosage of quinolones antibiotics could be cut when clove oil combined with quinolones antibiotics for treating MRSA infection.