沙门菌和志贺菌实验室能力比对验证的模拟粪便标本的研制和评估

Preparation of simulated stool specimens for proficiency testing scheme on the detection of Salmonella and Shigella

目的：研制适用于临床沙门菌和志贺菌实验室能力比对验证（ proficiency testing, PT）项目的模拟粪便标本,建立有效的标本制备与评估流程。方法分别把沙门菌、志贺菌和大肠埃希菌加标至基质扁豆中制成单一目标菌的模拟粪便标本；把不同比例的大肠埃希菌与沙门菌加标至基质扁豆中,制成混合菌的模拟粪便标本；用Cary-Blair运送培养基沾取混合物,制成PT标本。通过鉴定评估PT标本的准确性和稳定性。通过参与实验室反馈的鉴定结果评估外部质控考核结果。结果按100∶1~106∶1比例制备大肠埃希菌与沙门菌混合的PT标本,能在鉴定培养基有效分离两种菌落,按104∶1~106∶1的比例制备大肠埃希菌与沙门菌混合的PT标本,需增菌后才能有效分离沙门菌；16家参与实验室中有14家医院质控考核获得“满意”结果,占87.5%（14/16）,2家医院获得“基本满意”结果,占12.5%（2/16）。结论本研究制备的模拟粪便PT标本及实验质控流程适用于临床沙门菌、志贺菌及类似的微生物鉴定能力验证项目。

Objective To prepare simulated stool specimens for proficiency testing （ PT） by mix-ing lentils with Salmonella, Shigella and Escherichia coli strains and to establish an assessment scheme for the detection of Salmonella and Shigella in clinical samples. Methods Salmonella, Shigella and Escherich-ia coli strains were respectively spiked to lentils in Cary-Blair transport medium to create simulated stool specimens. Various ratios of Escherichia coli to Salmonella strains were spiked to lentils to prepare mixed simulated stool specimens. The accuracy and stability of prepared stool samples for PT were tested in-house. Results of sample detection were collected from participating laboratories for further external quality assess-ment. Results The Escherichia coli and Salmonella strains mixed at ratios of 100 ∶ 1 to 106 ∶ 1 could be ef-ficiently isolated from the media. Enrichment was needed in order to effectively isolate Salmonella strains from the media when the ratios of Escherichia coli to Salmonella strains were 104 ∶ 1 to 106 ∶ 1. Of the16 participating laboratories, 14 laboratories （87. 5%） received a grade of“satisfactory” and the other 2 labo-ratories （12. 5%） received a grade of “mainly satisfactory”. Conclusion The simulated stool specimens and the PT procedures designed in this study were suitable for proficiency testing program on the detection of Salmonella, Shigella and other similar microbes.