Determining Selenomonas Species Subclusters in Periodontal Samples by FISH

The highly destructive pathogenic processes in patients with periodontitis are attributed to the presence of subgingival biofilms comprising key periodontal pathogens, such as Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, as well as other periodontopathogens including Fusobacterium nucleatum, Selenomonas spp., Centipeda spp., and Campylobacter spp. Considering the vast microbial diversity in periodontitis, we aimed to analyze the presence of various bacterial species in subgingival dental plaque, with a special focus on Selenomonas spp. We first developed a phylogenetic tree for Selenomonas–Veillonella clusters, using in silico analysis followed by fluorescence in situ hybridization (FISH) on subgingival dental plaque samples from 22 patients with a history of chronic periodontitis, by using specific 16S rRNA oligonucleotide probes. These oligonucleotide probes’ specificity and hybridization conditions were determined on previously characterized bacterial strains. Qualitative and quantitative analysis of FISH slides was carried out by using an epifluorescence microscope. The majority of the patient samples showed high fluorescence signals with the oligonu