摘要
目的 研究启动子和衰减子突变与大肠埃希菌高产AmpC酶的关系。 方法 用琼脂稀释法、双纸片法、三相试验、等电聚焦电泳 (IEF)和聚合酶链反应 (PCR)检测其耐药机制 ,并对其AmpC的启动子和衰减子直接进行基因序列分析。衰减子的发夹状二级结构用DNASIS软件分析。结果 琼脂稀释法、双纸片法、三相试验、IEF和PCR证明这 4株菌都产染色体AmpC酶 ,基因序列分析提示它们在启动子和衰减子上都有不同程度的突变 ,同时还观察到其中一株菌的衰减子的G C发夹状二级结构由于突变导致△G 7.6kcal/mol的变化。
Objective To explore the relationship between 4 clinical isolations of E.coli hyperproducing the AmpC β lactamases and their mutations on promoter and attenuator. Methods Resistance mechanisms were investigated by agar dilution, double disk test, 3 D test, isoelectric focusing(IEF) and PCR. The direct sequencing was performed in the AmpC promoter and attenuator(PA) regions. Attenuator loop structure was calculated using DNASIS software. Results Double disk test, 3 D test, IEF and PCR indicated production of the chromosomal AmpC β lactamases in these 4 strains. Sequence analysis of the AmpC PA region revealed unique mutation combinations within both the promoter and attenuator. A novel attenuator GT mutation pair with △G of 7.6 kcal/mol was observed. Conclusion These data indicated that combinations of novel mutations within the promoter and attenuator were resulted to hyperproducing cephalosporinase.
出处
《上海医学检验杂志》
北大核心
2002年第4期204-207,共4页
Shanghai Journal of Medical Laboratory Sciences
