Thomson K S, Sanders C C, Moland E S
Center for Research in Anti-Infectives and Biotechnology, Creighton University School of Medicine, Omaha, Nebraska 68178, USA.
Antimicrob Agents Chemother. 1999 Jun;43(6):1393-400. doi: 10.1128/AAC.43.6.1393.
Over the past decade, a number of new beta-lactamases have appeared in clinical isolates of Enterobacteriaceae that, unlike their predecessors, do not confer beta-lactam resistance that is readily detected in routine antibiotic susceptibility tests. Because optimal methodologies are needed to detect these important new beta-lactamases, a study was designed to evaluate the ability of a panel of various beta-lactam antibiotics tested alone and in combination with beta-lactamase inhibitors to discriminate between the production of extended-spectrum beta-lactamases, AmpC beta-lactamases, high levels of K1 beta-lactamase, and other beta-lactamases in 141 isolates of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, and Serratia marcescens possessing well-characterized beta-lactamases. The microdilution panels studied contained aztreonam, cefpodoxime, ceftazidime, cefotaxime, and ceftriaxone, with and without 1, 2, and 4 microg of clavulanate per ml or 8 microg of sulbactam per ml and cefoxitin and cefotetan with and without 8 microg of sulbactam per ml. The results indicated that a minimum panel of five tests would provide maximum separation of extended-spectrum beta-lactamase high AmpC, high K1, and other beta-lactamase production in Enterobacteriaceae. These included cefpodoxime, cefpodoxime plus 4 microg of clavulanate per ml, ceftazidime, ceftriaxone, and ceftriaxone plus 8 microg of sulbactam per ml. Ceftriaxone plus 2 microg of clavulanate per ml could be substituted for cefpodoxime plus 4 microg of clavulanate per ml without altering the accuracy of the tests. This study indicated that tests with key beta-lactam drugs, alone and in combination with beta-lactamase inhibitors, could provide a convenient approach to the detection of a variety of beta-lactamases in members of the family Enterobacteriaceae.
在过去十年中，肠杆菌科临床分离株中出现了一些新型β-内酰胺酶，与它们的前辈不同，这些酶所赋予的β-内酰胺耐药性在常规抗生素敏感性试验中不易检测到。由于需要最佳方法来检测这些重要的新型β-内酰胺酶，因此设计了一项研究，以评估一组单独测试以及与β-内酰胺酶抑制剂联合测试的各种β-内酰胺抗生素，区分141株具有明确特征β-内酰胺酶的大肠杆菌、肺炎克雷伯菌、产酸克雷伯菌、阴沟肠杆菌、产气肠杆菌、弗氏柠檬酸杆菌和粘质沙雷氏菌中广谱β-内酰胺酶、AmpCβ-内酰胺酶、高水平K1β-内酰胺酶及其他β-内酰胺酶产生情况的能力。所研究的微量稀释板含有氨曲南、头孢泊肟、头孢他啶、头孢噻肟和头孢曲松，分别添加或不添加每毫升1、2和4微克的克拉维酸或每毫升8微克的舒巴坦，以及头孢西丁和头孢替坦，分别添加或不添加每毫升8微克的舒巴坦。结果表明，最少进行五项测试可最大程度区分肠杆菌科中广谱β-内酰胺酶、高AmpC、高K1及其他β-内酰胺酶的产生情况。这些测试包括头孢泊肟、头孢泊肟加每毫升4微克克拉维酸、头孢他啶、头孢曲松以及头孢曲松加每毫升8微克舒巴坦。每毫升头孢曲松加2微克克拉维酸可替代每毫升头孢泊肟加4微克克拉维酸，而不会改变测试的准确性。这项研究表明，使用关键β-内酰胺药物单独及与β-内酰胺酶抑制剂联合进行测试，可为检测肠杆菌科成员中的多种β-内酰胺酶提供一种便捷方法。
