没食子酸与5种抗生素联用对铜绿假单胞菌的体外抑菌活性

Antimicrobial Activity of Gallic Acid Combined with 5 Kinds of Antibiotics Against Pseudomonas aeruginosa in vitro

目的：研究没食子酸与5种常用抗生素联用对铜绿假单胞菌的体外抑菌活性。方法：收集铜绿假单胞菌标准菌株和10株临床分离菌株，采用琼脂平板稀释法分别测定没食子酸和5种常用抗生素（头孢他啶、氨曲南、左氧氟沙星、磷霉素和头孢曲松）对铜绿假单胞菌的最小抑菌浓度（MIC）；以MIC为始浓度，采用棋盘式微量稀释法测定没食子酸分别与5种抗生素单用及联用对铜绿假单胞菌的抑菌作用，以部分抑菌浓度指数（FICI）评价其联用效果；并以临床分离菌株IRPA314为目标菌株，采用时间．抑菌曲线进行验证。结果：5种抗生素均能降低没食子酸对11株铜绿假单胞菌的MIC，FICI均在0．188-1．000内，呈现较好的协同或相加作用。在时间．抑菌曲线中，没食子酸与5种抗生素联用24h时比单用时抑菌浓度的lg值均降低了2．085-3．416，均表现为协同作用。结论：没食子酸分别与头孢他啶、氨曲南、左氧氟沙星、磷霉素、头孢曲松联用对铜绿假单胞菌的体外抑菌作用表现为协同或相加作用。

OBJECTIVE： To study antimicrobial activity of gallic acid combined with 5 kinds of commonly used antibiotics against Pseudomonas aeruginosa （P aeruginosa） in vitro. METHODS： P aeruginosa standard strains and 10 strains of clinical iso- lates were collected. Agar dilution method was used to determine MIC of gallic acid combined with 5 kinds of commonly used anti- biotics as ceftazidime, aztreonam, levofloxacin, phosphonomycin and cefatriaxone against P. aeruginosa. Using MIC as initial con- centration, the trace checkerboard dilution method was used to determine antimicrobial effect of gallic acid alone or combined with 5 kinds of antibiotics against P. aeruginosa. Fractional inhibitory concentration index （FICI） was used to evaluate the effects of drug combination. Time-antibacterial curves were used to validate the trial results with clinical isolates IRPA 314 as target strain. RE- SULTS： 5 kinds of antibiotics could decrease the MIC of gallic acid against 11 kinds of P aeruginosa, and FICI of them were be- tween 0.188 and 1.000, presenting good synergy effect. In time-antibacterial curve, compared with alone, the inhibitory concen- tration （lg） of gallic acid combined with 5 kinds of antibiotics for 24 h reduced by 2.085-3.416, also showing the synergy effect. CONCLUSIONS： Gallic acid combined with ceftazidime, aztreonam, levofloxacin, phosphonomycin and cefatriaxone show syner- gy and additive antimicrobial effect against P aeruginosa.