Construction and Application of an In-House Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) Database Specific to Bacteria From Horses.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is used for identification of bacterial species isolated from horses. However, because of insufficiencies in the reference database, some bacterial species isolated from horses are difficult to identify with MALDI-TOF MS, and enriching the databases is expected to enhance the accuracy of MALDI-TOF MS identification. Here we created an in-house database including 271 bacterial isolates from horses. Furthermore, we used an enhanced database (our in-house database plus a commercially provided database) to examine 91 newly obtained isolates that could not be identified with MALDI-TOF MS using the commercially provided database. The enhanced database could identify 15 of those 91 isolates to the species level; including streptococcus (3/19), Gram-positive rod (4/17), Gram-negative rod (8/17) isolates. The enhanced database increased the average identification score of the 91 isolates (1.64-1.76). The in-house database increased the number of isolates that MALDI-TOF MS could identify to the species level and contributed to more accurate identification of bacterial isolates from horses.