Improvement of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for identification of clinically important Candida species.

Background: Matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS) is emerging as a rapid and accurate tool for identifying pathogens. MALDI-TOF identification of Candida at the species level remains unsatisfactory because of an incomplete commercial database.

Methods: Using Bruker Daltonics MALDI Biotyper software, an in-house spectral database library was created with m/z ratios of 2,000 to 20,000 Da from 60 successfully identified clinical isolates of Candida spp. (6 species). It was incorporated into the original database to produce the augmented Bruker-Tianjin database. The augmented database was tested with 347 clinical isolates of 6 species comparing with Bruker database in parallel.

Results: The identification rates at the species level were 91.6% (318/347) using the Bruker database and 99.1% (344/347) for the Bruker-Tianjin database.

Conclusions: Database expansion and refinement can easily and effectively improve MALDI-TOF MS performance for enhanced clinical pathogen identification.