MALDI-TOF MS自建数据库对丝状真菌临床分离株鉴定能力的评估

Evaluation of the MALDI-TOF MS in-house database in identification of clinical filamentous fungi isolates

目的评估MALDI-TOF MS自建数据库对丝状真菌临床分离株的鉴定能力。方法分子测序技术明确41株拟建库丝状真菌的种属信息。采用标准提取法分别对拟建库菌株幼稚菌落和成熟菌落进行MALDI-TOF MS自建数据库处理;另采用236株丝状真菌临床分离株评估该自建数据库的鉴定能力。结果41株建库丝状真菌分属于10属25种。自建数据库包含82张参考质谱图。采用MALDI-TOF MS自建数据库可将评估菌株种水平鉴定率由商业数据库的29.2%(69/236)提升至67.5%(159/236);将自建数据库与商业数据库联合后,评估菌株种水平鉴定率为76.3%(180/236),且无错误鉴定情况。与形态学方法相比,MALDI-TOF MS自建数据库对临床常见曲霉菌株的鉴定无优势,对于曲霉少见种和非曲霉丝状真菌,其种水平鉴定率为61.8%(34/55),显著优于形态学方法(16.4%,9/55)。结论MALDI-TOF MS自建数据库有助于提高实验室丝状真菌鉴定能力,在形态学方法鉴定困难的少见丝状真菌鉴定方面其作用更为显著。

Objective To evaluate the MALDI-TOF MS in-house database in identification of clinical filamentous fungi isolates.Methods Forty-one filamentous fungi isolates genetically confirmed by molecular sequencing method were used as the representative strains to construct the MALDI-TOF MS in-house database.The mass spectra profiles of the representative strains from young stage and mature stage colonies were created respectively according to the standard extraction procedure into the in-house database.The MALDI-TOF MS in-house database was challenged subsequently to identify other 236 clinical filamentous fungi isolates.Results The MALDI-TOF MS in-house database included 82 mass spectra profiles of 41 representative strains from 10 genera and 25 species.The species level identification rate of the 236 evaluated isolates could be increased from 29.2%(69/236)with the Bruker commercial library to 67.5%(159/236)with the MALDI-TOF MS in-house database;the highest species level identification rate was 76.3%(180/236)after combining the Bruker commercial library with the in-house database.There was no advantage of the MALDI-TOF MS in-house database in identification of common Aspergillus isolates than the morphological method.While for the cryptic species of Aspergillus and non-Aspergillus filemantous fungi,the species level identification rate was 61.8%(34/55)by the MALDI-TOF MS in-house database which significantly superior than the morphological method rate of 16.4%(9/55).Conclusions The in-house database could improve the performance of MALDI-TOF MS in identification of filamentous fungi isolates,especially for the less encountered species which were difficult to be identified with the conventional morphological method.