摘要
目的探讨在实验室条件下青霉素诱导金黄色葡萄球菌产生耐药性所需要的时间及浓度。方法将标准菌株接种到含不同浓度青霉素的营养肉汤培养液中,35℃孵育,每24 h更换1次培养液,每周做1次菌落计数及药敏试验,观察其药敏变化情况,直至培养生长菌株全部耐苯唑西林为止。结果青霉素对ATCC25923的最低抑菌浓度为0.313μg/mL。培养1周后各青霉素浓度培养液中均有菌株生长,且药敏试验都出现双圈,0.625～20μg/mL6个青霉素浓度的培养液中分别在2～7周后无菌生长;0.313、0.156、0.078μg/mL 3个青霉素浓度培养液中的生长菌株分别在6、7、3周全部耐苯唑西林。0.156μg/mL青霉素浓度诱导的耐药菌株,去除药物进行传代培养5周仍耐药;而0.313、0.078μg/mL2个浓度诱导的耐药菌株传代3周即恢复了对青霉素、苯唑西林的敏感性。结论青霉素浓度大于或等于0.625μg/mL为杀菌浓度,0.313、0.156、0.078μg/mL3个浓度易诱导金黄色葡萄球菌产生耐药,0.313及0.078μg/mL青霉素浓度诱导的耐药菌株耐药性不稳定,0.156μg/mL诱导的耐药菌株耐药性较稳定。
Objective To research the concentration of oxacillin and the time that induced Staphylococcus aureus to generate drug-resistance in vitro. Methods Inoculated standard strain ATCC25923 to bouillon which contains different concentration of oxacillin, then incubated with the temperature of 35 ℃, replaced the culture solution every 24 hours, counted coenobiums and experimentalizing susceptibility tests every week, the experiment was completed while all the strains generated resistance to oxacillin. Results the minimum inhibitory concentration （MIC） of oxacillin to ATCC25923 was 0. 313ug/ml. The bacteria grew under different concentration of oxacillin after 1 week＇s incubation, and two annulations were observed from susceptibility tests. There were no growing bacteria after 2--7 weeksrs cultivation under 6 different culture solution of oxacillin from 0. 625-20 ug/ml,. All the strains generated drug-resistance under the concentration of 0. 313,0. 156,0. 078 ug/ml oxacillin after 6,7,3 weeks cultivation respectively. The drug resistant strains induced by 0. 156 ug/mL oxacillin still had drug-resistance after 5 weeks serial subcultivation when oxacillin was removed from the culture solution. However,the drug resistant strains induced by 0. 313 and 0. 078 ug/mL oxacillin recovered sensitive to penicilin and oxacillin after 3 weeks serial subcultivation. Conclusion Exceeding 0. 625 ug/ml oxacillin have bactericidal effect on Staphylococcus aureus. The drug resistance can be induced with the concentration of 0. 313,0. 156 and 0. 078 ug/ml oxaeillin for Staphylococcus aureus, but the drug resistance of Staphylococcus aureus is unstable induced by the concentration of 0. 313 and 0. 078ug/ml oxacillin, however, the drug resistance is steady induced by the concentration of 0. 156ug/ml oxacillin.
出处
《国际检验医学杂志》
CAS
2010年第7期662-664,共3页
International Journal of Laboratory Medicine
关键词
青霉素类
葡萄球菌
金黄色
抗药性
细菌
penicillins
staphylococcus aureus
Drug Resistance, Bacterial
