目的 评价十二烷基硫酸钠(SDS)前处理方法在提高基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)直接鉴定阳性血培养样本准确率中的作用.方法 收集2016年3—9月阳性血培养瓶378瓶,试验前采用分离胶促凝管富集病原菌,试验后期增加SDS的洗涤过程,得到纯化的菌体后采用MALDI-TOF MS直接鉴定.同时对阳性血培养样本进行常规转种培养,获得纯菌落后采用MALDI-TOF MS鉴定,以此为最终结果,比较2种不同前处理方法的鉴定准确率.结果 未使用SDS洗涤的血样本87例,其中单种细菌感染的血样本83例,种鉴定准确率为73.5%,有4例为复数菌感染.使用SDS洗涤的血样本286例,其中单种细菌感染的血样本277例,种鉴定准确率为82.7%,有9例为复数菌感染.改良后革兰阳性菌的鉴定准确率从65.7%增加至90.5%,酵母的鉴定准确率从11.1%增加至50.0%,差异有统计学意义(P<0.05).结论 使用SDS洗涤处理的血培养阳性样本采用MALDI-TOF MS 直接鉴定,可提高血培养中主要病原菌的鉴定准确率,且操作简便、快速,成本低廉,适合在临床微生物实验室中应用.%Objective To improve the direct identification of microorganisms in positive blood culturing by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) with the pretreatment of sodium dodecyl sulfate(SDS). Methods A total of 378 blood culturing bottles were collected from March to September in 2016. Microorganisms were enriched and purified directly from blood culturing bottles by separation gel tube,washed by SDS,and then the samples were directly identified by MALDI-TOF MS. Traditional culturing and identification processes were performed simultaneously to be a reference. The accuracy of identification by MALDI-TOF MS with or without SDS pretreatment was compared. Results A total of 87 blood culturing samples without SDS washing were determined,and there were 83 cases of single strains and 4 cases of complex strains. The accurate species identification rate was 73.5%. The remaining 286 samples washed by SDS identified 277 cases of single strains and 9 cases of complex strains,and the accurate species identification rate was 82.7%. The identification rate for Gram-positive strains increased from 65.7% to 90.5%. Improvement was more frequent in yeast identification from 11.1% to 50.0% with statistical significance(P<0.05). Conclusions The preparation method,based on SDS washing,improves the identification rate of positive blood culturing directly by MALDI-TOF MS. It is easy-to-operation,time-saving and low-cost,which could be promoted in clinical microbiology laboratories.
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