耐头孢他啶大肠埃希氏菌超广谱β-内酰胺酶分析  

Analysis on characteristics of β-lactamases from E.coli resistant to ceftazidime

作　　者：吕媛[1] 

机构地区：[1]北京大学第一医院临床药理研究所,北京100083

出　　处：《中国抗生素杂志》2002年第8期465-469,共5页Chinese Journal of Antibiotics

摘　　要：目的　研究对头孢他啶耐药的大肠埃希氏菌产生的 β 内酰胺酶分子特性。方法　用平皿二倍稀释法挑选头孢他啶耐药的大肠埃希氏菌 ;用头孢他啶、头孢他啶 /克拉维酸、头孢噻肟、头孢噻肟 /克拉维酸纸片扩散法药物敏感实验确定超广谱 β 内酰胺酶产生菌 ;测定 β 内酰胺酶的分子量、等电点 ;提取质粒 ,基因组DNA进行PCR扩增测序。结果　共对 4株耐头孢他啶的大肠埃希氏菌产生的 β 内酰胺酶进行了分子特性研究 ,它们的MIC值 3 2～ 64mg/L ;纸片法联合药物敏感实验结果证明这 4株大肠埃希氏菌产超广谱 β 内酰胺酶 ;酶的分子量均是 2 8.10ku ;酶等电点测定结果显示有 2株大肠埃希氏菌各产生一种 β 内酰胺酶 ,它们的等电点是 6.8;另外 2株大肠埃希氏菌各产生 2种 β 内酰胺酶 ,它们的等电点分别是 6.8和 7.68。 4株大肠埃希氏菌都含有 1个质粒 ,PCR扩增结果为TEM型基因 ,其氨基酸序列与TEM 197%～ 98%等同 ,在 117位及 118位发生了氨基酸变异。结论　Aim: To study molecular characteristics of extended spectrum β lactamases (ESBLs) from 4 strains of E. coli resistant to ceftazidime. Methods: Clinical isolates of E.coli resistant to ceftazidime was selected by the agar dilution method; ESBLs producing strains was detected by the disc diffusion method; β lactamases were extracted from the selected strains of E.coli ; isoelectric point and molecular weight of β lactamases were determined; plasmid was extracted and genome DNA was sequenced by PCR amplification. Results: All four strains of E.coli were resistant to ceftazidime (MIC 32～64mg/L), but susceptible to the combination of ceftazidime or cefotaxime with clavulanic acid. And they all produced β lactamases, the molecular weight of these lactamases was 28.10 ku. The result of isoelectric point showed two strains of E. coli produced one β lactamase and the isoelectric point was 6.8. The other two strains of E.coli had two β lactamases and their isoelectric points were 6.8 and 7.68 respectively. All of four strains of E.coli contained one plasmid. The PCR amplification showd the gene was TEM type. They had 97%～98% identity with TEM 1, only at 117 and 118 position two amino acids were different from TEM 1. Conclusion: Four strains of E.coli resistant to ceftazidime, susceptible to ceftazidime/ clavulanate combination produced TEM type ESBLs which are probably new TEM type inhibitor sensitive beta lactamaes.

关 键 词：头孢他啶 大肠埃希氏菌 TEM型超广谱β-内酰胺酶 细菌耐药性 Β-内酰胺类抗生素 

分 类 号：R966[医药卫生—药理学] R978.1[医药卫生—药学]