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目的 探讨头孢哌酮 (MIC≥ 8mg/L)加舒巴坦后头孢哌酮的最低抑菌浓度 (MIC)降低2倍以上的肺炎克雷伯杆菌 β 内酰胺酶分子特性。 方法 用PCR扩增和DNA测序方法 ,测定分子量及等电点以及酶动力。结果 4株肺炎克雷伯杆菌含有TEM型基因 ,2株肺炎克雷伯杆菌TEM型酶的氨基酸序列与TEM 1相比在 117位及 118位发生了氨基酸变异。 4株肺炎克雷伯杆菌都产生 2种以上的酶 ,等电点从 5 4～ 9 3,相对分子量从 2 30 0 0～ 340 0 0。酶动力学研究表明 ,肺炎克雷伯杆菌中995 92及 996 0 7产生的酶能够水解头孢他啶、头孢噻肟及头孢曲松 ,并且 995 92的酶活性大于 996 0 7的酶活性。结论 肺炎克雷伯杆菌可能产生新的抑制剂敏感的TEM型超广谱酶。
Objective To investigate the molecular characteristics of Klebsiella pneumoniae β-lactamase in patients with cefoperazone (MIC ≥ 8 mg / L) and cefoperazone (MIC ≥ 2). Methods PCR amplification and DNA sequencing were used to determine the molecular weight, isoelectric point and enzyme kinetics. Results Four strains of Klebsiella pneumoniae contained the TEM gene. The amino acid sequence of two TEMs of Klebsiella pneumoniae showed an amino acid mutation at positions 117 and 118 compared with TEM 1. Four strains of Klebsiella pneumoniae produced more than two kinds of enzymes with isoelectric point from 54 to 93 and relative molecular weight from 2300 to 34000. Enzymatic kinetics studies showed that the enzymes produced by Klebsiella pneumoniae 99592 and 996 07 hydrolyzed ceftazidime, cefotaxime and ceftriaxone, and that the enzyme activity of 99592 was greater than 996 0 7. Conclusions Klebsiella pneumoniae may produce a new inhibitor-sensitive TEM-type ESBLs.