Matrix-assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) for subgingival bacteriome identification in a group of treated periodontitis patients: a case series

Periodontitis is a chronic multifactorial polymicrobial infection, characterized by profound modifications of the composition and proportion of the subgingival microbiota. Microbiological laboratory tests are sometimes used in periodontal diagnosis and monitoring of treatment, but both conventional cultivation methods and molecular techniques have some major drawbacks. Therefore, other performant bacterial identification methods must be considered. The aim of the current study was to use Matrix-assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALTI-TOF MS) analysis in association with bacterial culture method to evaluate the modifications of the subgingival bacterial composition in periodontitis patients, before and after cause-related subgingival therapy. Subgingival plaque samples were collected from periodontal pockets before and after subgingival mechanical instrumentation and adjunctive local antimicrobial applications and were cultured in aerobic and anaerobic conditions. Microbial colonies were further assessed using MALDI-TOF-MS. A total of 36 bacterial strains were isolated from a group of 16 patients. All species from the orange complex were identified by MALDI-TOF MS. A marked reduction of detection frequency was observed in most bacterial strains, including the orange complex after cause-related periodontal treatment. The results of this study indicate that MALDI-TOF MS could be considered an accurate method for oral microbial identification and the cause-related periodontal treatment is useful for reducing the microbial burden.