Analysis of the influence of Tween concentration, inoculum size, assay medium, and reading time on susceptibility testing of Aspergillus spp.
Analysis of the influence of Tween concentration, inoculum size, assay medium, and reading time on susceptibility testing of Aspergillus spp.
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DOI：
10.1128/jcm.43.3.1251-1255.2005
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发表时间：
2005-03-01
影响因子：
9.4
通讯作者：
Cuenca-Estrella, M
中科院分区：
文献类型：
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作者：
Gomez-Lopez, A;Aberkane, A;Cuenca-Estrella, M
几种试验变量对曲霉菌药敏试验的影响。进行了评估。对28株临床分离株进行了抗阿替霉素B、伊曲康唑、伏立康唑和特比萘芬的试验。接种量（10（4）CFU/ml vs 10（5）CFU/ml）和葡萄糖补充（0.2%对2%）对抗真菌药敏试验结果没有显著影响，更高的接种量和葡萄糖浓度不会错误地提高MIC。抗真菌药敏试验程序，接种量为10（5）CFU/ml，不同分化的阿替霉素B或伊曲康唑-抗性曲霉菌株与敏感菌株的体内比较。孵育时间显著影响MIC的最终值，在24和48 h的MIC读数之间显示出显著增加（2至6个两倍稀释，方差分析P < 0.01），但在48 h和72 h获得的抗真菌药敏试验结果之间没有观察到差异。显著更高的MIC与更高浓度的吐温（P < 0.01）一致相关，吐温在接种物混悬液的制备中用作分散剂。当吐温浓度从0.1%变化时，几何平均MIC显示出1.5- 10倍的增加。（阿替霉素B、伊曲康唑、伏立康唑和特比萘芬的几何平均值分别为1.29、0.69、1.06和0.64 μ g/ml）至5%（阿替霉素B、伊曲康唑、伏立康唑和特比萘芬的几何平均值分别为1.97、5.79、1.60和4.66 μ g/ml）。吐温的抑制作用明显增加，接种量为10（5）CFU/ml，特别是显着的伊曲康唑，特比萘芬，和土曲霉。当Tween浓度低于0.5%时，接种效果不明显（P > 0.01）.
The influence of several test variables on susceptibility testing of Aspergillus spp. was assessed. A collection of 28 clinical isolates was tested against amphotericin B, itraconazolle, voriconazole, and terbinafine. Inoculum size (10(4) CFU/ml versus 10(5) CFU/ml) and glucose supplementation (0.2 % versus 2 %) did not have significant effects on antifungal susceptibility testing results and higher inoculum size and glucose concentration did not falsely elevate MICs. In addition, antifungal susceptibility testing procedure with an inoculum size of 10(5) CFU/ml distinctly differentiated amphotericin B or itraconazole-resistant Aspergillus strains in vivo from the susceptible ones. Time of incubation significantly affected the final values of MICs, showing major increases (two to six twofold dilutions, P < 0.01 by analysis of variance) between MIC readings at 24 and 48 h, but no differences were observed between antifungal susceptibility testing results obtained at 48 h and at 72 h. Significantly higher MICs were uniformly associated with higher concentrations of Tween (P < 0.01), used as a dispersing agent in the preparation of inoculum suspensions. The geometric mean MICs showed increases of between 1.5- and 10-fold when the Tween concentration varied from 0.1 % (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.29, 0.69, 1.06, and 0.64 mu g/ml, respectively) to 5 % (the geometric means for amphotericin B, itraconazole, voriconazole, and terbinafine were 1.97, 5.79, 1.60, and 4.66 mu g/ml, respectively). The inhibitory effect of Tween was clearly increased with inoculum sizes of 10(5) CFU/ml and was particularly dramatic for itraconazole, terbinafine, and Aspergillus terreus. The inoculum effect was not observed when the Tween concentration was below 0.5 % (P > 0.01).