Normalized Resistance Interpretation as a Tool for Establishing Epidemiological MIC Susceptibility Breakpoints
Normalized Resistance Interpretation as a Tool for Establishing Epidemiological MIC Susceptibility Breakpoints
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DOI：
10.1128/jcm.01101-10
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发表时间：
2010-12-01
影响因子：
9.4
通讯作者：
Kronvall, Goran
中科院分区：
文献类型：
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作者：
Kronvall, Goran
归一化抗性解释（NRI）利用敏感侧的野生型群体不受抗性发展影响的事实，因此可以进行峰的归一化重建。通过引入辅助变量，对MIC分布的方法进行了修改，中间值指定为相邻分离株数量的平均值。该方法用于金黄色葡萄球菌和大肠埃希菌的MIC分布，每种27种抗菌剂，并从EUCAST（欧洲抗菌药物敏感性试验委员会）网站（http：//www.eucast.org/mic_distributions/）获得。在54个分布区中，每个分布区的分离株数量范围为40至124，472。NRI在所有情况下产生归一化分布。计算平均值以上+2.0和+2.5标准差（SD）的截止值，然后四舍五入至最接近的常规MIC稀释步骤。EUCAST还显示了截止值，ECOFF值，其用作参考。NRI生成的+2.0 SD值显示，对于金黄色葡萄球菌，27个样品中有26个在+/- 1稀释步骤内，17个与ECOFF值完全一致，对于大肠埃希菌，27个样品中有25个在+/- 1稀释步骤内，14个与ECOFF值完全一致。NRI提供了一种客观的方法，用于重建给定菌种和抗菌剂的MIC分布中的野生型种群。这种方法为比较敏感性研究提供了一种新的工具，例如全球耐药性监测以及单个实验室的质量控制。
Normalized resistance interpretation (NRI) utilizes the fact that the wild-type population on the sensitive side is not affected by resistance development, and therefore a normalized reconstruction of the peak can be performed. The method was modified for MIC distributions by the introduction of helper variables, in-between values assigned the mean of the neighboring numbers of isolates. This method was used on Staphylococcus aureus and Escherichia coli MIC distributions for 27 antimicrobials each and obtained from the EUCAST (European Committee on Antimicrobial Susceptibility Testing) website (http://www.eucast.org/mic_distributions/). The number of isolates in each of the 54 distributions ranged from 40 to 124,472. NRI produced normalized distributions in all cases. Cutoff values were calculated for +2.0 and +2.5 standard deviations (SD) above the means and then rounded up to nearest regular MIC dilution step. EUCAST also show cutoff values, ECOFF values, which were used as the reference. The NRI generated +2.0 SD values showed the best agreement with 26 of 27 within +/- 1 dilution step and 17 exactly on the ECOFF values for Staphylococcus aureus, and 25 of 27 within +/- 1 dilution step and 14 right on the ECOFF values for Escherichia coli. NRI offers an objective method for the reconstruction of the wild-type population in an MIC distribution for a given bacterial species and an antimicrobial agent. This method offers a new tool in comparative susceptibility studies such as global surveillance of resistance, as well as in quality control in individual laboratories.