We initiated a comparative study of four methods of yeast inoculum preparation: a spectrophotometric method, the Wickerham card method, a hemacytometer method, and the Prompt inoculation system. The variability in inoculum size obtained when each method was applied to two strains each of Candida albicans, Candida tropicalis, Candida parapsilosis, Torulopsis glabrata, Cryptococcus neoformans, and Saccharomyces cerevisiae was analyzed in a single laboratory. Each method was performed in triplicate on the same day and on three separate days to provide estimates of within-day and between-day variations. Inoculum size was determined by viable colony counts. The greatest range of inoculum sizes was seen with the Wickerham card method. Viable counts ranged from 1.1 X 10(6) to 24.2 X 10(6) CFU/ml among the 12 yeast isolates. The greatest variation was observed with the Prompt system. Within-day coefficients of variation averaged 19% (range, 4 to 45%), and between-day coefficients of variation averaged 22% (range, 3 to 51%). Variation between laboratories was evaluated by comparing inoculum values obtained by each method in three different laboratories for two strains of C. albicans. The spectrophotometric method was the least variable and the Wickerham card and hemacytometer methods were the most variable methods between laboratories. The spectrophotometric method is recommended as the method of choice for preparation of a standardized inoculum suspension for susceptibility testing of yeasts.
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机译：我们开始了四种酵母接种物制备方法的比较研究：分光光度法，Wickerham卡法，血细胞计数器法和Prompt接种系统。在单个实验室中分析了将两种方法分别应用于白色念珠菌，热带念珠菌，副产念珠菌，光滑拟弧菌，新隐球菌和酿酒酵母的两种菌株时接种物大小的变异性。每种方法在同一天和三天中一式三份进行，以提供日内和日间变化的估计值。接种量通过可行的菌落计数确定。用威克汉姆卡法观察到最大的接种量范围。在12个酵母菌分离物中，活菌计数范围为1.1 X 10（6）至24.2 X 10（6）CFU / ml。使用Prompt系统观察到最大的变化。日内变异系数平均为19％（范围为4至45％），日间变异系数平均为22％（范围为3至51％）。通过比较两种白色念珠菌菌株在三个不同实验室中每种方法获得的接种量来评估实验室之间的差异。在实验室之间，分光光度法变化最小，而Wickerham卡和血细胞计数器方法变化最大。建议使用分光光度法作为制备用于酵母敏感性测试的标准化接种物悬浮液的选择方法。
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