MALDI-TOF MS直接鉴定血培养阳性标本中的病原菌

Direct Identification of Pathogenic Bacteria of Positive Blood Culture by MALDI-TOF MS

目的建立分离胶促凝管联合基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)技术直接检测血培养阳性标本病原菌的方法并评估其鉴定的准确率。方法共收集阳性血培养200例,采用分离胶促凝管直接从血培养瓶中富集病原菌,采用MALDI-TOF MS对获得的待检菌进行菌种鉴定;同时对报阳血培养瓶进行转种培养,纯菌落用Vitek2 Compact全自动微生物分析系统(简称Vitek 2 Compact)进行鉴定,比对两种方法鉴定的符合率。若两者鉴定结果不一致,则采用基因测序法予以确定。结果阳性的血培养瓶中,革兰阴性菌主要是肺炎克雷伯菌、大肠埃希菌和鲍曼不动杆菌,种水平的鉴定符合率是77.9%(81/104),革兰阳性菌主要是表皮葡萄球菌、溶血葡萄球菌和金黄色葡萄球菌,种水平的鉴定符合率是59.0%(36/61),真菌主要是近平滑念珠菌、白色念珠菌和光滑念珠菌,种水平的鉴定符合率是75.9%(22/29)。结论本研究建立了分离胶促凝管直接离心法联合MALDI-TOF MS直接检测血培养阳性待测菌的方法,对血流感染中主要病原菌的鉴定符合率较高,且方法快速、简便、经济,具有很高的临床应用价值。

Objective To set up the direct identification of pathogenic bacteria of positive blood culture by a separation gel tube-based matrix-assisted laser desorption/ionization-time of flight mass spectrometry(MALDI-TOF MS)and to evaluate its identification accuracy.Methods A total of200cases with positive blood culture were collected;the pathogens were enriched and purified directly from blood culture bottle by separation gel tube and then identified by MALDI-TOF MS;traditional culture and identification processes were performed simultaneously and the cultured pure colonies were identified by Vitek2Compact automated microbial analysis system(Vitek2Compact);the identification of bacteria by MALDI-TOF MS was compared with that by traditional methods;gene sequencing was performed on discrepancies.Results The main Gram negative bacteria were Klebsiella pneumonia,Escherichia coli and Acinetobacter baumannii while the main Gram positive bacteria were Staphylococcus epidermidis,Staphylococcus haemolyticus and Staphylococcus aureus;the main fungi were Candida parapsilosis,Candida albicans and Candida tropicalis;the identification concordance rate in species was77.9%(81cases)in Gram-negative bacteria(104cases),59.0%(36cases)in Gram positive bacteria(61cases)and75.9%(22cases)in fungi(29cases).Conclusions The separation gel tube-based MALDI-TOF MS is of high concordance rate in identifying positive blood culture pathogens in bloodstreaminfection,it is simple,fast,less expensive and worthy of wider clinical application.