基质辅助激光解吸电离飞行时间质谱鉴定丝状真菌的影响因素分析  

Evaluation of Influence Factors in the Identification of Clinical Filamentous Fungi by Matrix Assisted Laser Desorption Ionization-time of Flight Mass Spectrometry

作　　者：李颖[1,2] 张戈[1,2] 杨洋[1,2] 李冬雪 王贺[1,2] 徐英春[1,2] LI Ying;ZHANG Ge;YANG Yang;LI Dong-xue;WANG He;XU Ying-chun(Department of Clinical Laboratory,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences&Peking Union Medical College,Beijing 100730,China;Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences&Peking Union Medical College,Beijing 100730,China)

机构地区：[1]中国医学科学院,北京协和医学院,北京协和医院检验科,北京100730 [2]中国医学科学院,北京协和医学院,北京协和医院侵袭性真菌病精准诊断与机制研究北京市重点实验室,北京100730

出　　处：《协和医学杂志》2020年第2期156-161,共6页Medical Journal of Peking Union Medical College Hospital

摘　　要：目的评估菌株培养条件、培养天数以及结果判定截断值(cut-off value,COV)3种因素对基质辅助激光解吸电离飞行时间质谱(matrix assisted laser desorption ionization-time of flight mass spectrometry,MALDI-TOF MS)鉴定丝状真菌能力的影响。方法将78株受试丝状真菌分别接种到沙堡弱葡萄糖琼脂(sabouraud dextrose agar,SDA)、土豆葡萄糖琼脂(potato dextrose agar,PDA)两种培养基及28、35℃两种培养温度共4种组合的培养条件下进行培养,并于培养第2、3、4、5天以及第7天对其进行MALDI-TOF MS分析,根据鉴定率的差异筛选菌株MALDI-TOF MS鉴定用最佳培养条件和培养天数;下调MALDI-TOF MS结果判定COV,分析其对MALDI-TOF MS丝状真菌鉴定率的影响。结果受试菌株在SDA和PDA两种培养基间的MALDI-TOF MS鉴定率无显著性差异(χ^2=0.467,P=0.792),但28℃培养温度下的鉴定率高于35℃培养温度(χ^2=7.195,P=0.027);培养第2、3天种水平(40.3%和34.3%)和属水平(44.8%和46.3%)鉴定率均较高;将MALDI-TOF MS种水平判定COV由>2.0下调至>1.7后,受试菌株种水平判定率显著提升(85.9%比32.1%,χ^2=40.119,P<0.01)且不增加错误鉴定率。结论丝状真菌以SDA或PDA培养基28℃培养2~3 d,并以分值>1.7作为种水平判定COV,可有效提高MALDI-TOF MS对丝状真菌的鉴定能力。Objective This study aimed to evaluate the potential influence of culture conditions,incubation time,and the interpreting cut-off value(COV)in the identification of filamentous fungi by matrix-assisted laser desorption ionization-time of flight mass spectrometry(MALDI-TOF MS).Methods Seventy-eight isolates of filamentous fungi were cultivated in sabouraud dextrose agar(SDA)or potato dextrose agar(PDA)media with an incubation temperature of 28℃or 35℃separately,namely four different culture conditions.MALDI-TOF MS identification was carried out at different time including the 2 nd,3 rd,4 th,5 th and 7 th days of incubation of the isolates.Differences in identification capacities of MALDI-TOF MS under the tested parameters were analyzed to determine the optimal culture condition and incubation time of filamentous fungi.The influence of lowered interpreting COV in MALDI-TOF MS identification of filamentous fungi was also evaluated.ResultsNo significant difference was detected between the SDA and PDA culture media in the identification capacities of MALDI-TOF MS(χ^2=0.467,P=0.792).The identification capacity of MALDI-TOF MS with the incubation temperature of 28℃was superior to that of 35℃(χ^2=7.195,P=0.027).Higher identification rates of species level(40.3%,34.3%)and genus level(44.8%,46.3%)were achieved in isolates incubated for 2 and 3 days.The identification rate of species level was increased significantly from 32.1%to 85.9%(χ^2=40.119,P<0.01)without increasing the false identification rate after adjusting the interpreting COV from score>2.0 to>1.7.Conclusion The performance of MALDI-TOF MS in the identification of filamentous fungi could be improved by applying the optimal culture condition of incubating in SDA or PDA media under the temperature of 28℃for 2 to 3 days and by adjusting the interpreting COV of the species level with a score>1.7.

关 键 词：基质辅助激光解吸电离飞行时间质谱 丝状真菌 鉴定 影响因素 

分 类 号：R446.5[医药卫生—诊断学]