MALDI-TOF MS直接鉴定腹水培养阳性样本的研究

目的 探讨用基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)直接鉴定腹水培养阳性病原菌的方法.方法 收集2016年9～11月培养阳性的腹水标本202瓶,差速离心法富集菌体,利用MALDI-TOF MS对菌液进行直接鉴定.结果 202瓶样本中,196瓶为单菌株感染,6瓶为混合菌感染.单菌株感染中,菌株的种、属鉴定符合率分别为77.6％和93.4％.其中革兰阴性菌的种、属鉴定符合率为75.9％和91.1％;革兰阳性菌的种、属鉴定符合率为80.2％和95.3％;真菌的菌种、属鉴定符合率为12.5％和50.0％.6瓶混合菌感染样本,均鉴定出其中一种菌.结论 利用MALDI-TOF MS直接鉴定腹水培养阳性样本中的病原菌,鉴定准确率高,检测时间短,为腹腔感染的快速诊断提供了有力的检测手段.

Direct identification of microorganisms from positive ascites culture by MALDI-TOF MS

Objective To evaluate the direct identification of pathogens from positive ascites culture by Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS).Methods A total of 202 culture positive ascites samples from microbiology laboratory in the Beijing You'an Hospital during September to November 2016 were collected.The bacteria were enriched by differential centrifugation,and then the bacteria were identified by MALDI-TOF MS.The identification of bacterial isolates by MALDI-TOF MS was compared with that of routine bacterial identification assay.Results Among 202 positive ascites culture samples,196 were monomicrobial cultures and 6 were polymicrobial cultures.Of 196 monomicrobial cultures,the method showed 77.6 ％ and 93.4％ concordance to species and genus identification rates.The accuracy of identification in species and genus level were 75.9％ and 91.1％ in gram-negative bacteria (79 cases),were 80.2％ and 95.3％ in gram-positive bacteria (106 cases),and were 12.5％ and 50.0％ in fungus (8 cases).In 6 cases of polymicrobial cultures,only one of bacteria was identified to genus level.Conclusion Direct identification of pathogens in ascites culture samples by MALDI-TOF MS could reduce turn around time,which provide a rapid and accurate method for the diagnosis of abdominal infection.