MALDI-TOF MS在临床曲霉菌鉴定中的应用

Application of MALDI-TOF MS in identification of clinical Aspergillus

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）在临床曲霉菌属鉴定中的应用,并评价其鉴定性能.方法 以ITS测序结果为金标准,对解放军总医院2017年5月至2018年4月临床分离的曲霉菌属采用VITEK MS V3.0进行鉴定,并对结果进行分析.结果 通过V3.0数据库（含12种曲霉菌图谱）鉴定了9种曲霉菌,占总体分离菌株的86.24%.VITEK MSV3.0的鉴定符合率为91.49%,未获得结果的占16.51%;菌属符合率为93.62%,其中仅有两株杂色曲霉鉴定到属水平.根据鉴定置信度进行统计,88.30%的菌株获得了99%以上的鉴定率.首次未获得鉴定结果的占13.83%,鉴定错误率3.19%,二次提取后再次进行质谱鉴定未鉴定菌株降低到6.38%,鉴定错误率降到2.13%;结合传统鉴定和VITEK MS鉴定手段,属正确率为98.94%,种正确率为93.62%;其他真菌对曲霉菌鉴定的影响度为0%.结论 MALDI-TOF MS作为传统鉴定方法的有力补充,应用于曲霉菌鉴定给工作带了很多便捷,提高了种水平鉴定准确率,使得真菌实验室鉴定水平得到了提高.

Objective To discuss the application of matrix assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF MS ） in the identification of Aspergillus and evaluate its performance. Methods the clinical isolates of Aspergillus collected from May 2017 to March 2018 in PLA General Hospital were identified by VITEK MS V3.0 and the results were analyzed. The ITS sequencing resultswere used as the gold standard. Results It identified 9 Aspergillus species （ including 12 Aspergillus species in total ） through the V3.0 database, accounting for 86.24% of the total clinical isolates. The identification rate by VITEK MS was 91.49% with 16.51% was not identified. The coincidence rate of genus was 93.62% , of which only two Aspergillus versieolor were identified to the level of the genus. According to the confidence level analysis, 88. 30% of the strains obtained more than 99% of the identification rate. 13.83% of the strains did not have the identification results for the first time, with the error rate of 3. 19%. After secondary extractions, the percentage of unidentified strain was reduced to 6.38% , and the identification error rate was reduced to 2.13%. Combined with traditional identification and VITEK MS identification, the correct rate of strains identification was 98.94% on genus level, and was 93.62% on species level. The influence of other fungi on Aspergillus identification was 0%. Conclusion As a powerful supplement to the traditional identification method, MALDI-TOF MS showed a lot of convenience when applied in the identification of Aspergillus, which improves the identification accuracy and the identification ability for fungi in laboratory.