杜慧竟 石继春 李江姣 王春娥 徐潇 陈翠萍 叶强

[摘要] 目的 比较平板点样法与传统平板涂布计数法，建立更为简便的细菌悬液中活菌浓度的检测方法。 方法 将3株A群溶血性链球菌制备成多份菌悬液，稀释成不同梯度，用调理吞噬实验中的平板点样技术和传统平板涂布法同时检测，比较两种方法计数结果，分析相关性和显著差异。 结果 不同菌株和稀释方法中平板点样法的结果均随菌液稀释梯度呈现出较好的梯度；两种方法计数结果呈高度相关（r = 0.84）；二者的t检验结果比较差异无统计学意义（P > 0.05）。 结论 相对平板涂布法，平板点样法计数更客观准确，检测范围更宽，操作更便捷，适用于菌液浓度的确定。

[关键词] A群溶血性链球菌；细菌悬液；浓度测定；平板菌落计数

[中图分类号] R446.5 [文献标识码] A [文章编号] 1673-7210（2016）02（c）-0146-04

Comparison of two plate count methods of bacterial density determination

DU Huijing SHI Jichun LI Jiangjiao WANG Chun'e XU Xiao CHEN Cuiping YE Qiang▲

Key Laboratory for Standardization of Methods for Quality Control of Biotechnical Products， Ministry of Health， National Institutes for Food and Drug Control， Beijing 100050， China

[Abstract] Objective To establish a more convenient detection method for determining concentrations of living bacteria in suspensions by comparing spot plate method with common spread plate method. Methods 3 groups of A Streptococcus strains were cultured and separately suspended in normal saline and diluted. The concentrations of the suspensions were detected by both spot plate method and spread plate method. The relationship and significant difference between the results from the two methods were analyzed. Results The counting results of different strains or diluting way suspensions from spot plates appeared a great dilution gradient dependence. The results of the two methods showed a good correlation， r = 0.84， and there was no significant difference in t-test （P > 0.05）. Conclusion Compared with spread plate method， spot plate method is a more objective and convenient method for bacteria counting， which also has a wide counting range.

[Key words] Group A Streptococcus； Bacteria suspension； Concentration determination； Plate culture count

在臨床细菌诊断试剂盒的评价过程中，菌液浓度的确定是参考品制备的关键步骤，因此菌液浓度的测定方法应当准确、便捷。目前，菌液浓度的测定和参考品的制备常用浊度法（包括比浊法、分光光度法等）和平皿计数法[1-6]，但浊度法难以区分活菌与死菌，以及与微生物大小类似的杂质[7]。传统用于测定菌液内活菌量的方法主要是平板涂布法。此方法虽结果较为准确，但可计数浓度范围窄，且人眼计数不够客观；操作复杂，所需时间较长，当制备大批量参考品时，其计数工作量也变得不可忽视，更易因疲劳而使误差变大。

平板点样计数法是调理吞噬实验（opsonophagocytic assay，OPA）中的细菌浓度检测方法。调理……