MALDI-TOF MS is a rapid, reliable, economical, and environmentally friendly method for routine microbial identification and may contribute to early appropriate antibiotic treatment in clinical settings.

We conclude that this method is feasible for clinical use in microbiology laboratories, and can serve as a reference for treatments or further complementary diagnostic testing.

The purpose of this study was to identify the microbial communities that colonize peri-implantitis pockets using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Subjects having at least one implant with peri-implantitis, no diabetes, and not taking antibiotics in the previous 3 months were selected. Peri-implantitis was defined when surrounding bone loss ≥0.5 mm and bleeding on probing was found. Microbial samples were collected from peri-implantitis pockets using paper points. After incubation and isolation, the colonies were analyzed by MALDI-TOF MS. A total of 126 isolates were cultivated and identified from 12 samples, in identification rates of 82.5% at the species level and 12.72% at the genus level. Although the compositions were highly variable, major habitants in different peri-implant pockets could be identified. Among them the most distinguished were Neisseria flavescens (87%), Streptococcus constellatus (56%), Slackia exigua (46%), Streptococcus intermedius (45%), Fusobacterium nucleatum (45%) and Gemella morbillorum (43%). This preliminary study provides comprehensive and reliable data for future study designs involving MALDI-TOF MS and peri-implantitis in a more specific, easy, rapid and economical way. MALDI-TOF MS could be a new clinical method to evaluate and monitor oral microbiota associated with the disease.

Prolonged vancomycin usage may cause methicillin-resistant Staphylococcus aureus to become vancomycin-intermediate S. aureus (VISA) and heterogeneous VISA (hVISA). Mechanisms of vancomycin resistance of VISA and hVISA are still unclear. In this study, analyses of nucleotide sequence variations in 30 vancomycin-sensitive S. aureus (VSSA), 41 hVISA and 16 VISA isolates revealed 29 single-nucleotide variations in 12 genes (fmtC, graR, graS, htrA, mecA, pbp2, pbp4, srtA, tcaA, upps, vicK and vraR) that are related to cell wall synthesis or the two-component system. Six of these 29 single-nucleotide variations were novel and resulted in the following amino acid changes: Q692E in FmtC; T278I, P306L and I311T in HtrA; and I63V and K101E in Upps. Since P306L and I311T in HtrA and I63V in Upps were present in the majority (76.7%–86.7%) of VSSA isolates, these three amino acid variations may not be associated with vancomycin resistance. The other three amino acid variations (T278I in HtrA, K101E in Upps and Q692E in FmtC) were present in the majority (87.5%–93.8%) of hVISA and VISA isolates, but only in a small number (22.9%–25.7%) of VSSA isolates, suggesting that they are associated with vancomycin resistance.