3种氟喹诺酮类药物联合苦豆子碱对牛源致病性粪肠球菌耐药突变选择窗的影响

Effects of Sophora albumen combined with three kinds of fluoroquinolones on mutant selection window of pathogenic Enterococcus faecalis isolated from bovine

目的研究苦豆子碱与3种氟喹诺酮类药物（环丙沙星、恩诺沙星、氧氟沙星）联用对粪肠球菌耐药突变选择窗（MSW）的影响。方法采用二倍稀释法测定环丙沙星、恩诺沙星、氧氟沙星对粪肠球菌标准株ATCCA29212、牛源分离株的最小抑菌浓度（MIC）;采用平板诱导法,用环丙沙星、恩诺沙星、氧氟沙星筛选粪肠球菌标准株及牛源分离株的第一步耐药突变体,用环丙沙星筛选得到第二步耐药突变体;采用二倍稀释法检测环丙沙星、恩诺沙星、氧氟沙星对耐药突变体的MIC、最小防突变浓度（MPC）,计算突变选择指数（SI）并确定MSW,观察苦豆子碱和3种氟喹诺酮类药物联用对粪肠球菌MSW的影响。结果3种氟喹诺酮类药物对2株分离的粪肠球菌的MIC均〉 1. 6μg·mL（-1）,MPC均〉 20μg·mL（-1）,SI为3. 4～13. 7;与原菌株比较,经不同氟喹诺酮类药物筛选的粪肠球菌的MIC升高了3～7倍,MPC升高了2～7倍;苦豆子碱和3种氟喹诺酮类药物联用（4MIC＋2MIC）可使抗菌药物对粪肠球菌的MSW缩小2～4倍。结论连续使用同一类型的抗菌药物能快速、加宽粪肠球菌的MSW,从而诱导耐药菌的产生;苦豆子碱和3种氟喹诺酮类药物联用有利于杀灭致病性粪肠球菌,防止耐药菌出现。

OBJECTIVE To study the influence of Sophora albumen combined with three kinds of fluoroquinolones（ Ciprofloxacin,Enrofloxacin and Ofloxacin） on the mutant selection window（ MSW） of Enterococcus faecalis isolated from bovine. METHOD The MICs of three kinds of fluoroquinolones on E. faecalis ATCC29212 and the clinical isolate from bovine were determined by agar plates dilution method. The first-step resistant mutants of E. faecalis ATCC29212 and bovine E. faecalis were selected by Ciprofloxacin,Enrofloxacin and Ofloxacin. The second-step resistant mutants were selected by Ciprofloxacin. Then the MICs and MPC of fluoroquinolones for E. faecalis resistant mutants were evaluated by agar plates dilution to calculate the MSW and the value of selection index（ SI）. Finally,the effects and characteristics of the MSW of E. faecalis were observed through the combined use of the S. albumen and Ciprofloxacin,Enrofloxacin and Ofloxacin. RESULTS The MICs of three kinds of fluoroquinolones for two bovine E. faecalis were greater than 1. 6 μg·mL^（-1）,the MPC were greater than 20 μg·mL^（-1） with the SI of 3. 4 to 13. 7. Compared with the original strain,the MIC of E. faecalis selected by different fluoroquinolones increased 3 to 7 times,while the MPC increased 2 to 7 times. S. albumen combined with fluoroquinolones（4 MIC ＋ 2 MIC） decreased MSW of E. faecalis to Ciprofloxacin,Enrofloxacin and Ofloxacin for 2-4 times. CONCLUSION It showed that continuous use of the same type of antibiotic drugs can quickly widen the E. faecalis MSW to induce drug-resistant bacteria. S. albumen combined with fluoroquinolones are more favorable to antibiotics to kill the pathogenic E.faecalis,thus preventing the emergence of resistant bacteria.