Biocide susceptibility testing (BST) of bacteria lacks standardised methods. Based on a recently established broth macrodilution BST method, a broth microdilution method for BST was developed. To establish the respective protocol, four reference strains Staphylococcus aureus ATCC® 6538, Enterococcus hirae ATCC® 10541, Escherichia coli ATCC® 10536 and Pseudomonas aeruginosa ATCC® 15442 were investigated for their minimal inhibitory concentrations (MICs) towards quaternary ammonium compounds (benzalkonium chloride), cationic compounds (chlorhexidine), aldehydes (glutardialdehyde) and alcohols (isopropanol) using tryptic soy broth. All combinations of (i) inoculum preparation according to the German Veterinary Medical Society (DVG) or the Clinical and Laboratory Standards Institute (CLSI) with some modifications, (ii) use of 1^st subculture (SC) and 2^nd SC, (iii) direct colony suspension (DCS) with/without glass beads, and (iv) incubation at 37 °C for 24 h, 48 h, and 72 h were compared using seven independent replications. Overall, the reproducibility was high for all abovementioned strain/biocide/parameter combinations. In total, 86.9 % – 100 % of the results were within ± one dilution step of the mode value. The proposed method for a standardised BST protocol comprises (i) two different inoculum densities, (ii) the use of a fresh overnight culture (1^st SC or 2^nd SC), (iii) the preparation of the inoculum suspension by either of the two methods using DCS with or without glass beads, and (iv) the incubation at 37 °C for 24 h. This broth microdilution method will help to harmonize BST of bacterial pathogens in routine diagnostics.

细菌的杀菌剂敏感性测试（BST）缺乏标准化的方法。基于最近建立的肉汤微量稀释BST方法，开发了一种BST肉汤微量稀释方法。为了建立相应的方案，使用四个参考菌株金黄色葡萄球菌ATCC®6538，平肠肠球菌ATCC®10541，大肠杆菌ATCC®10536和铜绿假单胞菌使用胰蛋白酶大豆肉汤研究了ATCC®15442对季铵化合物（苯扎氯铵），阳离子化合物（氯己定），醛（戊二醛）和醇（异丙醇）的最小抑菌浓度（MIC）。的所有组合（i）将根据德国兽医医学协会（DVG）或临床和实验室标准研究所（CLSI）有一些修改，（ⅱ）使用1次的接种物制备^ST传代培养（SC）和2^次使用七次独立复制比较了SC，（iii）有/无玻璃珠的直接菌落悬浮液（DCS）和（iv）在37°C下孵育24小时，48小时和72小时。总体而言，所有上述菌株/杀生物剂/参数组合的重现性均很高。总共有86.9％– 100％的结果在模式值的±1个稀释步之内。对于标准化的BST协议包括所提出的方法（i）两种不同的接种密度，（ⅱ）使用新鲜过夜培养物（1 ^ST SC或2^次SC），（iii）通过任一的制备接种物悬浮液的两种方法分别使用带或不带玻璃珠的DCS，以及（iv）在37°C下孵育24小时。这种肉汤微稀释方法将有助于在常规诊断中协调细菌病原体的BST。