目的：利用基质辅助激光解吸电离飞行时间质谱（ MALDI-TOF MS）技术建立血流感染病原菌快速、准确的鉴定方法。方法连续收集苏州大学附属第二医院检验科2015年1至7月血培养仪阳性报警血培养瓶266个，抽吸血培养瓶中血液至血清分离胶管，采用差速离心法富集细菌，利用MALDI-TOF MS对富集后的菌液进行快速鉴定，并与传统培养24～48 h后形成的菌落最终鉴定结果进行比较。结果266个阳性血培养样本中，260个为单菌株血流感染，6个为混合菌感染。在260例单菌株所致血流感染中，菌株的属、种鉴定符合率分别为98．8％（257／260）和96．2％（250／260）。其中，140株革兰阴性菌属、种鉴定符合率分别为99．3％（139／140）和97．9％（137／140）；120株革兰阳性菌属、种鉴定符合率分别为98．3％（118／120）和94．2％（113／120）。6例混合菌感染未得到鉴定结果。结论本研究利用MALDI-TOF MS对差速离心富集后的菌液进行直接鉴定，有效缩短了检测时间，而且鉴定准确率高，为血流感染的快速诊断提供了有力的检测手段。%Objective To develop a rapid and accurate technique for pathogens identification from positive blood cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry ( MALDI-TOF MS) .Methods A total of 266 culture-positive blood samples from clinical laboratory in the Second Affiliated Hospital of Soochow University during January to July 2015 were collected.The blood was transferred into separation-gel tubes, and the bacteria were enriched and purified by differential centrifugation.MALDI-TOF MS was applied to identify the bacteria and the results were compared with conventional bacterial culture. Results Among 266 culture-positive blood samples, 260 were monomicrobial cultures and 6 were polymicrobial cultures.Of 260 monomicrobial cultures, 98.8% (257/260) and 96.2% ( 250/260 ) of organisms were identified at the genus level and the species level, respectively.Of 140 Gram-negative bacterial isolates, 99.3% (139/140) and 97.9% (137/140) were identified at the genus level and the species level, respectively.Of 120 Gram-positive bacteria isolates, 98.3%(118/120) and 94.2% (113/120) were identified at the genus level and the species level, respectively.None of the 6 polymicrobial cultures were identified.Conclusion MALDI-TOF MS can directly identify the bacteria from positive blood cultures, which provides a rapid and accurate method for the diagnosis of bloodstream infection.
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