The inoculum density is an important parameter for numerous experimental approaches in bacteriology, including antimicrobial susceptibility testing (AST), biocide susceptibility testing (BST) and biocide efficacy testing (BET). Methods to determine the inoculum density commonly refer to cell counts and have been described for BET according to the German Medical Veterinary Society (Deutsche Veterinärmedizinische Gesellschaft, DVG) and for AST according to the Clinical and Laboratory Standards Institute (CLSI). In this study, the DVG method using 1000 μL volumes of two different dilution steps and the AST method according to CLSI using a 100 μL volume of a single dilution step from the inoculum suspension were compared. For this, each of the four reference strains, Staphylococcus aureus ATCC® 6538, Enterococcus hirae ATCC® 10541, Escherichia coli ATCC® 10536 and Pseudomonas aeruginosa ATCC® 15442, was comparatively tested 28 times using the inoculum preparation according to DVG. The results were statistically analysed using Bland-Altman plots and 95 % limits of agreement (AL). Moreover, cell counts were correlated with the optical density of the bacterial suspensions used. In comparison, the CLSI method measured lower values for colony-forming units (CFU) of -0.12 log₁₀ compared to the DVG method. Overall, both methods returned an AL of -0.52 to 0.27 log₁₀. Since the variations observed between the two methods were within one log₁₀ step and the measured CFUs did not differ systematically, both methods proved to be suitable for cell count determination. Therefore, the CLSI method, which is less complex and less time-consuming, is recommended.

接种密度是许多细菌学实验方法的重要参数，包括抗菌药敏试验（AST），杀菌剂药敏试验（BST）和杀菌剂功效试验（BET）。确定接种密度的方法通常是指细胞计数，根据德国医学兽医学会（DeutscheVeterinärmedizinischeGesellschaft，DVG）的BET和根据临床和实验室标准协会（CLSI）的AST进行了描述。在这项研究中，比较了使用1000μL体积的两个不同稀释步骤的DVG方法和根据CLSI使用接种物悬浮液中100μL体积的单个稀释步骤的AST方法。为此，四个参考菌株金黄色葡萄球菌ATCC®6538，使用根据DVG的接种物，对平肠肠球菌ATCC®10541，大肠杆菌ATCC®10536和铜绿假单胞菌ATCC®15442进行了28次比较测试。使用Bland-Altman图和95％的协议限（AL）对结果进行统计分析。此外，细胞计数与所用细菌悬浮液的光密度相关。相比之下，与DVG方法相比，CLSI方法测得的菌落形成单位（CFU）值为-0.12 log ₁₀。总体而言，这两种方法均返回-0.52至0.27 log ₁₀的AL 。由于两种方法之间观察到的差异在1 log ₁₀以内步骤和测得的CFU没有系统地不同，这两种方法都证明适用于细胞计数测定。因此，建议使用CLSI方法，该方法不太复杂且耗时较少。