Mirrett S, Reller L B
J Clin Microbiol. 1979 Oct;10(4):482-7. doi: 10.1128/jcm.10.4.482-487.1979.
To determine the reliability of early antimicrobial susceptibility testing, we compared the results of direct and standard single-disk diffusion methods for 581 positive blood cultures processed routinely by the clinical microbiology laboratory. The direct procedure differed from the standard one only in that the 0.5 McFarland inoculum was prepared from 1 ml of turbid broth rather than five isolated colonies from a subculture plate. A major discrepancy in results was defined as a change from susceptible to resistant or vice versa according to interpretive standards for zone diameters, whereas a minor discrepancy was defined as a shift to or from the intermediate category when paired direct and standard tests were compared. The overall agreement between the two methods was 94.6% of 2,308 comparisons. There were 119 minor (5.2%) and 6 major (0.3%) discrepancies. The major discrepancies were seen with three strains of Staphylococcus epidermidis and one strain each of S. aureus, Escherichia coli, and Enterobacter sp. Direct susceptibility testing of positive blood cultures that were pure by gram-stained smear provided reliable results 24 to 36 h earlier than conventional procedures; therefore, we recommended this procedure to guide early antimicrobial therapy in patients with bacterial sepsis.
为确定早期抗菌药物敏感性试验的可靠性，我们比较了临床微生物实验室常规处理的581份阳性血培养物的直接法和标准单碟扩散法的结果。直接法与标准法的不同之处仅在于，0.5麦氏浊度接种物是由1ml浑浊肉汤制备的，而不是来自传代培养平板的五个分离菌落。根据抑菌圈直径的解释标准，结果的主要差异定义为从敏感变为耐药或反之，而当比较配对的直接法和标准法试验时，次要差异定义为向中间类别或从中间类别转变。两种方法之间的总体一致性在2308次比较中为94.6%。有119次次要差异（5.2%）和6次主要差异（0.3%）。主要差异见于三株表皮葡萄球菌以及一株金黄色葡萄球菌、一株大肠杆菌和一株肠杆菌。革兰氏染色涂片显示为纯菌的阳性血培养物的直接药敏试验比传统方法早24至36小时提供可靠结果；因此，我们推荐该方法用于指导细菌性败血症患者的早期抗菌治疗。
