摘要
目的 探讨主动外排机制在金黄色葡萄球菌 (简称金葡菌 )对喹诺酮类抗生素耐药性产生中的作用、特性及对策。方法 将金葡菌标准株ATCC2 5 92 3及对喹诺酮类敏感的临床株接种于含 4×最低抑菌浓度 (MIC)氧氟沙星的Muller Hinuton(MH)琼脂平板上 (含或不含 2 0 μg/ml的利血平 ) ,观察利血平对诱导耐药株出现的抑制作用 ,并测定诱导耐药株对溴乙啶、氧氟沙星、环丙沙星的MIC(含或不含 2 0 μg/ml的利血平 ) ,观察利血平对诱导耐药株MIC的影响 ,并使用溴乙啶与金葡菌脱氧核糖核酸结合后的荧光增强特性 ,观察其在菌体内的积聚 ,用利血平抑制试验法测定临床上耐喹诺酮类金葡菌中主动外排机制的流行性。结果 通过利血平对菌体内溴乙啶的影响 ,显示耐二代喹诺酮的金葡菌存在主动外排机制 ,利血平可降低喹诺酮类药对金葡菌 5 0 %的诱导耐药率 ,降低诱导耐药株的MIC ,减少菌体对溴乙啶的外排。结论 主动外排是金葡菌耐喹诺酮类抗菌药物的重要机制之一 ,利血平可抑制其主动外排作用 ,与喹诺酮类抗菌药物有协同作用 ,为临床提供了克服金葡菌耐药的新思路。
Objective To explore the effect, the characteristic,and potential approaches to the active efflux mechanism in straphylococcus aureus(S.a) resistant to quinolones. Methods S.a standard strain ATCC25923 and clinical isolates susceptible to quinolone were inoculated onto MH agar containing ofloxacin at a concentration of 4× MIC(in the presence or absence of 20 μg of reserpine/ml).Following incubation at 35℃ for 48 h, the inhibiting effect of reserpine on the occurence of induced resistance was observed and the MIC of the induced resistant strain to ethidium bromide(EB),ofloxacin and ciprofloxacin(in the prevence or absence of 20 μg of reserpine/ml) was determined.The influence of reserpine to the MIC of induced resistant strains was also determined.The accumulation and loss of EB was determined based on the fact that EB′s fluorescence can be strengthened when combined whth DNA. Reserpine inhibition test was used to study the active efflux in clinical S.a resistant to quinolone. Results The active efflux mechanism in S.a resistant to second generation quinolones was confirmed by the reserpine′s influence on the level of ethidium bromide(EB) in the cytoplasm of S.a. Reserpine reduced the 50 percent resistant rate to quinolone in induced resistant S.a, and decreased the MIC of induced resistant strains. Reserpine inhibited the active efflux of EB from the cytoplasm of S.a. Conclusions Active efflux is an important mechnism in S.a resistant to quinolone. Reserpine can inhibit its active efflux mechanism, and has synergistic effect with quinolone, which hold therapeutic potential for S.a resistant to quinolones.
出处
《中华结核和呼吸杂志》
CAS
CSCD
北大核心
2004年第6期403-406,共4页
Chinese Journal of Tuberculosis and Respiratory Diseases
