临床分离耐药菌中超广谱β－内酰胺酶特性研究

CHARACTERIZATION OF EXTENDED-SPECTRUMβ-LACTAMASES OF CLINICAL RESISTANTS

本文报道我国临床分离超广谱β－内酰胺酶的特性。采用超声破碎法提取β－内酰胺酶，超薄层（０．４ｍｍ）聚丙烯酰胺等电聚焦电泳测定等电点ｐＩ，采用凝胶过滤层析法测定分子量，紫外分光光度法测定酶动力学参数。结果表明，６株临床分离致病菌所产β－内酰胺酶为头孢噻肟酶，其中Ｎｏ．４４７，Ｎｏ．８７７和Ｎｏ．１０９１对头孢噻肟的相对有效水解率（Ｖｍａｘ／Ｋｍ）较高，分别为１１２％，５０．８％和１０８％。６个超广谱酶都有较高等电点，ｐＩ＞７．０。酶抑制剂青霉烷砜对６个超广谱酶均有较强的抑制作用，Ｋｉ≤０．０５μｍｏｌ／Ｌ；０．１μｍｏｌ／Ｌ棒酸除可抑制Ｎｏ．４４７酶外，对其他５个超广谱酶无明显的抑制作用。

We report the cefotaxime-hydrolyzingβ-lactamases produced by 6 clinical isolates,and determine the isoelectric points,molecular weights,kinetic properties and inhibitiori profiles.The result showed that enzymes No.447,No.877 and No.109l hydrolyzed cefotaxime strongly,their relative effective hydrolysis(Vmax/Km)were 112%,50.8% and 108%,respectively.The 6 extended-spectrumβ-lactamases had high isoeletric points(pI>7.0),and were inhibited by sulbactam(Ki≤0.05μmol/L).Clavulanate inhibited enzyme No.447,(Ki=0.0835μmol/L)and couldrit inhibite the other 5β-lactamases at concentration 0.1μmol/L.