基质辅助激光解析电离飞行时间质谱技术在病原菌鉴定中的应用

Application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry system in identification of pathogenic bacteria

目的探讨基质辅助激光解析电离飞行时间质谱技术(MALDI-TOF MS)在快速鉴定血流感染病原菌的应用价值,并分析MALDI-TOF MS方法鉴定病原菌的准确性。方法收集321例血流感染患者的血液标本进行血培养,微生物室细菌培养结果均为阳性。从血培养阳性瓶中取病原菌至分离胶促凝管中,应用MALDI-TOF MS对富集的病原菌进行菌种鉴定。同时,对血培养瓶中的阳性标本进行常规培养,获得的纯菌落采用VITEK 2 COMPACT微生物分析系统进行检测,并将MALDI-TOF MS检测结果与VITEK 2 COMPACT结果进行对比。若检测结果有差异,则进一步进行基因测序法予以确定。结果321例阳性血培养标本中共分离出180株革兰阴性杆菌,MALDI-TOF MS鉴定准确率为97.78%,无鉴定错误,但4株无鉴定结果;分离出的141株革兰阳性菌中,主要以革兰阳性球菌为主,MALDI-TOF MS鉴定准确率为84.39%,1株蜡样芽胞杆菌误鉴定为大肠埃希菌,出现了菌属水平鉴定错误,其余为种类鉴定错误。结论与传统血培养及生化鉴定比较,MALDI-TOF MS在血流感染中的鉴定符合率较高,且鉴定方法简便、迅速。

Objective To explore the value of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)in the rapid identification of pathogenic bacteria in bloodstream infections,and to analyze the accuracy of MALDI-TOF MS method.Methods Blood samples from 321 patients with bloodstream infection were collected for blood culture,and the results of bacterial culture in microbiology laboratory were all positive.Pathogenic bacteria was taken from the positive blood culture flask and placed into a separate gel tube,and MALDI-TOF MS was used to identify the enriched bacteria;at the same time,the samples were routinely cultured,and the pure colonies obtained were detected by VITEK 2 COMPACT microbial analysis system,and the identification results of the two methods were compared.If there were differences in the test results,further gene sequencing method would be carried out to determine.Results Among 321 specimens for blood culture,180 strains of Gram-negative bacilli were isolated,the identification accuracy rate of MALDI-TOF MS was 97.78%,no identification errors occurred and 4 strains were not identified.Among 141 strains of Gram-positive bacteria isolated,the Gram-positive coccus accounted for the most,and the identification accuracy rate of MALDI-TOF MS was 84.39%.One strain of Bacillus cereus was mistakenly identified as Escherichia coli,and there was an error in the identification of the genus level;the remaining was identified incorrectly at the level of the species.Conclusion Compared with traditional blood culture and biochemical identification methods,MALDI-TOF MS method has a higher accordance rate in bloodstream infection,and the method is simple and rapid.