粪肠球菌感染抗菌药物联合应用的体外效应研究

Antibacterial effects of six antimicrobial agents combined with cefathiamidine on Enterococcus faecalis:an in vitro study

目的 评价万古霉素、奈替米星、阿米卡星、环丙沙星、左氧氟沙星和加替沙星 6种抗菌药物分别与第一代头孢菌素头孢硫脒联合用药 ,对于临床分离的粪肠球菌 (Enterococcusfaecalis,Ef)的体外联合抗菌效应。方法 采用棋盘法设计 ,微量肉汤稀释法测定。测定不同浓度组合的 6组抗菌药物对 30株临床分离的革兰阳性球菌的最低抑菌浓度 ,并计算FIC指数。FIC≤ 0 .5为协同作用 ,0 .5 <FIC≤ 1为相加作用 ,1 <FIC≤ 2为无关作用 ,FIC >2为拮抗作用。结果 头孢硫脒对粪肠球菌的MIC50 为 2～ 8mg L ,与万古霉素、奈替米星、阿米卡星、环丙沙星、左氧氟沙星、加替沙星联合应用后 ,其MIC50 分别显著地降低至 0 .1 2 5 ,0 .2 5 ,0 .2 5 ,0 .2 5 ,0 .2 5 ,0 .2 5mg L。FIC指数分布 :FIC≤ 0 .5占 50 %～ 86 .7% ;0 .5 <FIC≤ 1占 1 3 .3 %～ 36 .7% ;1 <FIC≤ 2占 0～ 1 3 .3 % ;FIC >2为 0。结论 6种抗菌药物与头孢硫脒分别联合用药后 ,对粪肠球菌基本表现为协同作用和相加作用 ,并以协同作用为主 ,无关作用较少 。

Objective To evaluate the antibacterial effects of vancomycin,netilmicin,amikacin,ciprofloxacin, levofloxacin and gatifloxacin respectively combined with cefathiamidine on 30 strains of Enterococcus faecalis. Methods The protocol was designed with checkerboard method. The minimum inhibitory concentrations(MICs) of cefathiamidine alone and combined with 6 antimicrobial agents against the 30 strains of E. faecalis were determined by broth dilution method and the FIC(fraction inhibitory concentration) index was calculated according to MICs results. Results The MIC 50 of cefathiamidine alone against E. faecalis was 2mg/L and the MIC 50 of cefathiamidine combined with vancomycin, netilmicin, amikacin, ciprofloxacin, levofloxacin or gatifloxacin was reduced to 0.25, 0.5, 0.25,0.25,0.25,0.25mg/L, respectively. The percentages of the FIC index less than 0.5, from 0.5 to 1, from 1 to 2,and more than 2 were 50% 86.7%, 13.3 36.7%, 0 13.3% and 0, respectively. Conclusions The FIC indexes indicate that cefathiamidine combined with vancomycin, netilmicin, amikacin, ciprofloxacin, levofloxacin or gatifloxacin respectively has synergic or additive antibacterial effect on 30 strains of Enterococcus faecalis and the primary action is synergism. There is little autonomy and no antagonism.