Application of MALDI-TOF MS in identification of clinical Aspergillus

Abstract

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 versicolor 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.(Chin J Lab Med, 2018, 41: 577-582) Key words: Aspergillus; Mycological typing techniques; Spectrometry, mass, matrix-assisted laser desorption-ionization