Comparison of three different in vitro methods of detecting synergy: Time-kill, checkerboard, and E test
Comparison of three different in vitro methods of detecting synergy: Time-kill, checkerboard, and E test
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DOI：
10.1128/aac.40.8.1914
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发表时间：
1996-08-01
影响因子：
4.9
通讯作者：
Bosso, JA
中科院分区：
文献类型：
--
作者：
White, RL;Burgess, DS;Bosso, JA
需要一种检测协同作用的体外方法，该方法操作简单、准确、可重复并且具有临床外推的潜力。时间消耗法和棋盘法是评估协同作用最广泛使用的技术，但它们耗时耗力。Epsilometer试验（E试验）是一种技术要求较低的试验，尚未对协同试验进行充分的研究。我们采用时间杀伤、格板试验和E试验技术对头孢吡肟或头孢他啶与妥布霉素或环丙沙星的各种组合进行了大肠埃希菌ATCC 35218、阴沟肠杆菌ATCC 23355、铜绿假单胞菌ATCC 27853和金黄色葡萄球菌ATCC 29213的协同试验。分别对每种微生物单独和以1/4倍MIC（1/4倍MIG）和2倍MIG组合进行时间杀伤测试。通过棋盘试验，在1/32至4倍MIG的浓度范围内研究了相同的组合。使用了协同、冷漠和对抗的标准定义。将E试验条以90度角交叉，使各药物单独在MIC处相遇，并根据所产生的抑制区计算抑菌浓度分数指数。所有抗菌药物组合对试验菌均表现出一定程度的协同作用，拮抗作用较少，与时间杀伤试验的一致性分别为44 ~ 88%和63 ~ 75%。尽管每种方法都使用不同的条件和终点，但方法之间经常存在一致意见，因此有必要进一步比较E测试协同技术与棋盘和时间消耗方法。
An in vitro method of detecting synergy which is simple to perform, accurate, and reproducible and has the potential for clinical extrapolation is desirable. Time-kill and checkerboard methods are the most widely used techniques to assess synergy but are time-consuming and labor-intensive. The Epsilometer test (E test), a less technically demanding test, has not been well studied for synergy testing, We performed synergy testing of Escherichia coli ATCC 35218, Enterobacter cloacae ATCC 23355, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 29213 with various combinations of cefepime or ceftazidime with tobramycin or ciprofloxacin using time-kill, checkerboard, and E test techniques. Time-kill testing was performed against each organism alone and in combinations at one-fourth times the MIC (1/4x MIG) and 2x MIG. With checkerboard tests, the same combinations were studied at concentrations ranging from 1/32x to 4x MIG. Standard definitions for synergy, indifference, and antagonism were utilized. E test strips were crossed at a 90 degrees angle so that the scales met at the MIC of each drug alone, and the fractional inhibitory concentration index was calculated on the basis of the resultant zone of inhibition, All antimicrobial combinations demonstrated some degree of synergy against the test organisms, and antagonism was infrequent, Agreement with time-kill testing ranged from 44 to 88% and 63 to 75% by the checkerboard and E test synergy methods, respectively, Despite each of these methods utilizing different conditions and endpoints, there was frequent agreement among the methods, Further comparisons of the E test synergy technique with the checkerboard and time-kill methods are warranted.