Identification of Fusobacterium Species Using Matrix-Assisted Laser Desorption/Ionization-Time- of-Flight Mass Spectrometry by Updating ASTA CoreDB

Abstract

Purpose: Fusobacterium species can cause infections, and associations with cancer are being increasingly reported. As their clini-cal significance differs, accurate identification of individual species is important. However, matrix-assisted laser desorption/ion-ization-time of flight mass spectrometry has not been found to be effective in identifying Fusobacterium species in previous stud-ies. In this study, we aimed to improve the accuracy and efficacy of identifying Fusobacterium species in clinical laboratories. Materials and Methods: In total, 229 Fusobacterium isolates were included in this study. All isolates were identified at the species level based on nucleotide sequences of the 16S ribosomal RNA gene and/or DNA-dependent RNA polymerase beta-subunit gene (rpoB). Where necessary, isolates were identified based on whole genome sequences. Among them, 47 isolates were used for up-dating the ASTA database, and 182 isolates were used for the validation of Fusobacterium spp. identification. Results: Fusobacterium isolates used for validation (182/182) were correctly identified at the genus level, and most (180/182) were correctly identified at the species level using the ASTA MicroIDSys system. Most of the F. nucleatum isolates (74/75) were correctly identified at the subspecies level. Conclusion: The updated ASTA MicroIDSys system can identify nine species of Fusobacterium and four subspecies of F. nuclea-tum in good agreement. This tool can be routinely used in clinical microbiology laboratories to identify Fusobacterium species and serve as a springboard for future research.