Henriksen T H, Brorson O, Schöyen R, Thoresen T
Department of Microbiology, Vestfold Sentralsykehus, Tönsberg, Norway.
Eur J Clin Microbiol Infect Dis. 1996 Jun;15(6):484-8. doi: 10.1007/BF01691316.
The correlation between metronidazole MIC readings obtained in vitro on two different media for two different inoculum dilutions was studied after two, three, and five days of incubation using 20 clinical isolates of Helicobacter pylori. The PDM epsilometer (E test) was used. After two days of incubation, log MIC values on chocolate PDM and Vestfold charcoal medium, a new charcoal medium, showed good correlation. Charcoal media can thus be used for metronidazole sensitivity tests. In terms of double-dilution gradients, prolongation of incubation time from two to three days and change of inoculum dilution from 0.5 to 4 McFarland had little impact when studied separately. However, the combined effect of the two variables was marked. The matching of a sparse inoculum incubated for two days against a heavy inoculum incubated for three days resulted in readings which, for 30% of the pairs, differed by two double-dilution gradients or more. On the other hand, the separate influence of both variables was found to affect the correlation coefficients significantly. Five days of incubation was associated with a poor correlation when the variables on MIC readings was not exposed in a scale of double-dilution gradients because the intervals were too large. For this reason, scales without thresholds are recommended.
使用20株幽门螺杆菌临床分离株，研究了在两种不同培养基上针对两种不同接种物稀释度进行体外培养2天、3天和5天后获得的甲硝唑MIC读数之间的相关性。使用了PDM比浊仪（E-test）。培养2天后，巧克力PDM和一种新的木炭培养基——韦斯特福尔木炭培养基上的对数MIC值显示出良好的相关性。因此，木炭培养基可用于甲硝唑敏感性试验。就双倍稀释梯度而言，单独研究时，培养时间从2天延长至3天以及接种物稀释度从0.5麦氏浊度变为4麦氏浊度影响不大。然而，这两个变量的综合作用很明显。将培养2天的稀疏接种物与培养3天的浓密接种物相匹配，结果显示，30%的配对读数相差两个或更多双倍稀释梯度。另一方面，发现这两个变量的单独影响均显著影响相关系数。当MIC读数的变量未以双倍稀释梯度呈现时，培养5天与相关性较差有关，因为间隔太大。因此，建议使用无阈值的刻度。
