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目的 研究鲍氏不动杆菌对喹诺酮类药物的耐药机制。方法 对临床上收集的耐环丙沙星鲍氏不动杆菌进行氟罗沙星摄取试验、外膜蛋白电泳、PCR扩增 gyrA和parC基因、酶切分析和测序。结果 耐药株药物聚积量不及敏感株的 1/2 ,经碳酰氰间氯苯腙 (CCCP)处理后 ,聚积量上升并接近敏感株 ;经SDS PAGE电泳 ,耐药株与敏感株比较 ,外膜蛋白在约 2 9ku条带处消失 ,而 2 4ku处条带却明显增强 ;PCR RFLP分析 ,gyrA基因能产生 1条DNA片段 ,而 parC基因则能产生 2条片段 ;测序结果显示 ,其GyrA蛋白中所编码 83位 (相应于大肠埃希氏菌 )氨基酸由丝氨酸变为亮氨酸 ,ParC蛋白未见氨基酸改变。结论 该株对环丙沙星耐药鲍氏不动杆菌存在DNA促旋酶变异 ,药物主动外运及外膜的改变。
Objective To study the mechanism of quinolones resistance in Acinetobacter baumanii. Methods The Clostridium acuminatum-resistant Acinetobacter baumannii was collected clinically and tested for fleroxacin uptake, outer membrane protein electrophoresis, PCR amplification of gyrA and parC genes, restriction analysis and sequencing. Results The accumulation of drug-resistant strains was less than 1/2 of that of the susceptible strain. After treatment with CCCP, the accumulation of drug-resistant strains increased and approached the susceptible strain. Compared with susceptible strains by SDS PAGE electrophoresis, The outer membrane protein disappeared at about 29 ku bands and the band at 24 ku was significantly enhanced. PCR RFLP analysis showed that gyrA gene could produce one piece of DNA while parC gene could produce two fragments. Sequencing results showed that GyrA protein encoding 83 (corresponding to Escherichia coli) amino acid from serine to leucine, ParC protein no amino acid change. Conclusion The strains of Ciprofloxacin-resistant Acinetobacter baumannii have DNA gyrase variation, active drug delivery and outer membrane changes.