Wiggins G L, Albritton W L, Feeley J C
Antimicrob Agents Chemother. 1978 May;13(5):854-60. doi: 10.1128/AAC.13.5.854.
A broth microdilution method was used to measure the minimal inhibitory concentrations (MICs) of the antibiotics most often recommended for treatment of listeriosis. The MICs of ampicillin, penicillin, erythromycin, and tetracycline for 175 strains of Listeria monocytogenes were below the approximate MIC breakpoint for susceptible strains as recommended by the National Committee on Clinical Laboratory Standards. Inhibition diameters for 125 strains were measured by the standardized disk method (National Committee on Clinical Laboratory Standards) and compared with the appropriate MIC values. By both methods, strains were susceptible to the above four antibiotics, except for three strains, which were intermediate in susceptibility to penicillin by the disk method. Since the minimal bactericidal concentrations for ampicillin and penicillin significantly exceeded the MICs for these antibiotics, 45 strains were evaluated with ampicillin (5 mug/ml) and gentamicin (1 mug/ml) to compare the synergistic bactericidal effect of the two used in combination and singly. An increased kill of 100-fold was observed with the antibiotics combined in 19 strains after 4 to 6 h and in 40 strains after 24 h. A comparison of results with microdilution in Trypticase soy broth and agar dilution in Mueller-Hinton agar revealed that MICs for gentamicin, kanamycin, and streptomycin were strongly influenced by the media used. The MICs were consistently lower in Mueller-Hinton agar.
采用肉汤微量稀释法测定最常用于治疗李斯特菌病的抗生素的最低抑菌浓度（MIC）。氨苄西林、青霉素、红霉素和四环素对175株单核细胞增生李斯特菌的MIC低于美国国家临床实验室标准委员会推荐的敏感菌株的大致MIC断点。用标准化纸片法（美国国家临床实验室标准委员会）测定了125株菌株的抑菌圈直径，并与相应的MIC值进行比较。通过这两种方法，除3株菌株用纸片法检测对青霉素敏感性为中度外，其余菌株对上述四种抗生素均敏感。由于氨苄西林和青霉素的最低杀菌浓度显著超过这些抗生素的MIC，因此对45株菌株用氨苄西林（5μg/ml）和庆大霉素（1μg/ml）进行评估，以比较两者联合使用和单独使用时的协同杀菌效果。联合使用抗生素时，19株菌株在4至6小时后杀菌效果提高了100倍，40株菌株在24小时后杀菌效果提高了100倍。胰蛋白酶大豆肉汤微量稀释法与穆勒-欣顿琼脂平板稀释法结果比较显示，庆大霉素、卡那霉素和链霉素的MIC受所用培养基的强烈影响。在穆勒-欣顿琼脂中，MIC始终较低。
