Principles of assessing bacterial susceptibility to antibiotics using the agar diffusion method
Principles of assessing bacterial susceptibility to antibiotics using the agar diffusion method
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DOI：
10.1093/jac/dkn090
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发表时间：
2008-06-01
影响因子：
5.2
通讯作者：
Parisot, Judicael
中科院分区：
文献类型：
--
作者：
Bonev, Boyan;Hooper, James;Parisot, Judicael
目的：琼脂扩散试验是一种定量测定抗生素抑制细菌生长能力的方法。对该试验结果的解释依赖于模型依赖分析，该分析基于抗生素在固体营养培养基中自由扩散的假设。在许多情况下，这种假设可能是不正确的，这导致预测的行为与实验的显著偏差，并导致细菌对抗生素敏感性的不准确评估。我们寻求琼脂扩散试验的理论描述，考虑到扩散过程中抗生素的损失，并提供从该试验确定的更高准确性的MIC。方法：我们提出了一个新的琼脂扩散分析的理论框架。利用该技术测定了多种抗生素的MIC，并使用现有的自由扩散模型和新的耗散扩散模型进行了分析。结果：描述了一种分析抗生素在固体介质中扩散的理论，其中我们考虑了扩散过程中测试抗生素与固体介质或部分抗生素失活的可能相互作用。这与分析疏水或两亲化合物的扩散特别相关。该模型基于一个广义扩散方程，该方程将现有理论作为一个特例，并包含一个附加的耗散项。结论：使用新模型分析琼脂扩散实验可以更准确地解释实验结果和测定mic。该模型具有更普遍的有效性，并适用于其他耗散过程的分析，例如抗原扩散和亲和纯化中底物负荷的计算。
Objectives: The agar diffusion assay is one method for quantifying the ability of antibiotics to inhibit bacterial growth. Interpretation of results from this assay relies on model-dependent analysis, which is based on the assumption that antibiotics diffuse freely in the solid nutrient medium. In many cases, this assumption may be incorrect, which leads to significant deviations of the predicted behaviour from the experiment and to inaccurate assessment of bacterial susceptibility to antibiotics. We sought a theoretical description of the agar diffusion assay that takes into consideration loss of antibiotic during diffusion and provides higher accuracy of the MIC determined from the assay.Methods: We propose a new theoretical framework for analysis of agar diffusion assays. MIC was determined by this technique for a number of antibiotics and analysis was carried out using both the existing free diffusion and the new dissipative diffusion models.Results: A theory for analysis of antibiotic diffusion in solid media is described, in which we consider possible interactions of the test antibiotic with the solid medium or partial antibiotic inactivation during diffusion. This is particularly relevant to the analysis of diffusion of hydrophobic or amphipathic compounds. The model is based on a generalized diffusion equation, which includes the existing theory as a special case and contains an additional, dissipative term.Conclusions: Analysis of agar diffusion experiments using the new model allows significantly more accurate interpretation of experimental results and determination of MICs. The model has more general validity and is applicable to analysis of other dissipative processes, for example to antigen diffusion and to calculations of substrate load in affinity purification.