乳粉中克罗诺杆菌属阪崎肠杆菌能力验证样品制备及应用

Preparation and application of proficiency test sample of Cronobacter spp. (Enterobacter sakazakii) in milk powder

目的制备均匀性及稳定性均满足要求的克罗诺杆菌属(阪崎肠杆菌)检验能力验证样品,用于组织能力验证考核。方法通过生化及基质辅助激光解吸电离飞行时间质谱方法鉴定背景菌株及所使用的克罗诺杆菌属(阪崎肠杆菌)菌株。采用冷冻干燥技术制备均匀性及稳定性均满足要求且各种菌含量为10^(4)CFU/瓶的能力验证菌球。依据CNAS-GL003∶2018《能力验证样品均匀性和稳定性评价指南》,随机抽取阳性样品和阴性样品各20份进行均匀性检验,再将样品存放于-20℃、4℃进行保藏稳定性检验,存放于25℃、37℃进行运输稳定性检验。依据GB 4789.40—2016制定作业指导书并发放样品,回收各实验室结果进行统计。结果目的菌株及背景菌株的鉴定结果均正确,均匀性、运输稳定性及保藏稳定性检验均符合能力验证样品的要求。依据评价原则及25家实验室反馈的结果,2021年度考核结果满意率为100%。结论乳粉中克罗诺杆菌属(阪崎肠杆菌)能力验证样品满足本年度能力验证的要求,为参加考核的检测机构提供了外部质控考核结果。

Objective To prepare Cronobacter spp.(Enterobacter sakazakii) proficiency test samples which meet the requirements of uniformity and stability, and use them for proficiency test. Methods The background strains and Cronobacter. spp were identified by biochemical and matrix-assisted laser desorption ionization time of flight mass spectrometry method. Freeze-drying was used to prepare the samples with 10^(4)CFU/bottle. According to Guidance on Evaluating the Homogeneity and Stability of Samples Used for Proficiency Testing, 20 samples were selected randomly for uniformity test. The samples were stored at-20 and 4 ℃ respectively to evaluate the storage stability, and at 25 and 37 ℃ to evaluate the transport stability. According to GB 4789.40—2016, samples were distributed to participating laboratories with operation instruction, and then the feedback result were analyzed. Results The identified result of all the related strains were correct and consistent with expectations. The result of uniformity and stability tests met relevant requirements. All of the experiment result submitted by 25 laboratories within the required time were correct, and the satisfaction rate was 100%. Conclusion The samples of Cronobacter spp. Enterobacter sakazakii in milk powder proficiency test can meet the relevant requirements, and this proficiency test provides external quality control assessment result for the participating labratories simultaneously.