Performance of MALDI-TOF MS for identification of oral Prevotella species

- MALDI-TOF MS identifies reliably Prevotella species included in its database.
- The identification accuracy of MALDI-TOF MS is close to that of 16S rRNA partial sequencing.
- Due to the intra-species diversity, the database needs to be expanded with a number of strains within each species.
- An enhanced species coverage, including the novel species, is a further requirement.

During the past decade, the clinically relevant genus Prevotella has expanded considerably. Prevotella species can be isolated from nearly all types of oral infections but also from various non-oral infections. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been introduced in clinical microbiology laboratories as a convenient method for identifying bacterial isolates from clinical specimens. Here we tested the diagnostic accuracy of a total of 123 oral Prevotella isolates, selected based on their biochemical profile, by Bruker MALDI-TOF MS. Partial 16S rRNA sequencing was used as a reference method. The performance of MALDI-TOF MS to identify the isolates to the genus level was excellent with 100.0% accuracy, while a good identification rate of 88.6% was achieved to the species level with a log score of ≥2.0. The isolates representing P. aurantiaca and P. jejuni, which are currently missing from the MALDI BioTyper database, were identified correctly to the genus level. Of the 123 isolates, one P. pallens isolate (0.8%) was identified with a score variation of 1.7-1.999. Overall, biochemical testing produced a high proportion (70.7%) of incorrect identifications within different species. MALDI-TOF MS offers a reliable and rapid method for the identification of Prevotella species included in the database.