Microbial complexes in subgingival plaque.
Level 4 - case-series / case-control
Cross-sectional observational study assessing bacterial co-occurrence and clinical associations.
PubMed 9495612 · doi:10.1111/j.1600-051x.1998.tb02419.x
What was done
Subgingival plaque samples were collected from the mesial aspect of each tooth across 185 subjects (mean age 51 ± 16 years; 160 with periodontitis, 25 without periodontitis), yielding 13,261 total plaque samples. Clinical assessments were conducted at 6 sites per tooth. The presence and levels of 40 subgingival bacterial taxa were measured using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Pairwise species similarities were evaluated using phi coefficients, species clustering was performed via averaged unweighted linkage sort, and community ordination was analyzed using principal components analysis and correspondence analysis.
What was found
Five major microbial complexes consistently emerged across all analytical methods: 1. A complex consisting of Bacteroides forsythus, Porphyromonas gingivalis, and Treponema denticola, which related strikingly to clinical measures of periodontal disease, particularly pocket depth and bleeding on probing. 2. A complex with a core of Fusobacterium nucleatum/periodonticum subspecies, Prevotella intermedia, Prevotella nigrescens, and Peptostreptococcus micros, associated with Eubacterium nodatum, Campylobacter rectus, Campylobacter showae, Streptococcus constellatus, and Campylobacter gracilis. 3. A complex of Streptococcus sanguis, Streptococcus oralis, Streptococcus mitis, Streptococcus gordonii, and Streptococcus intermedius. 4. A complex containing three Capnocytophaga species, Campylobacter concisus, Eikenella corrodens, and Actinobacillus actinomycetemcomitans serotype a. 5. A complex of Veillonella parvula and Actinomyces odontolyticus. Actinobacillus actinomycetemcomitans serotype b, Selenomonas noxia, and Actinomyces naeslundii genospecies 2 were outliers showing little relationship to each other or the five complexes. Exact numerical correlation coefficients were not reported in the abstract.
Why it matters
This study defined the foundational microbial community structure of subgingival plaque, demonstrating that specific bacterial species co-occur in distinct consortia rather than acting solely as independent pathogens in periodontal disease.
Limits
The study is cross-sectional, precluding any conclusions regarding temporal succession or direct causality in disease development. Microbial detection was restricted to a targeted panel of 40 pre-selected taxa. The study population was unbalanced, with far more periodontitis subjects (n = 160) than healthy controls (n = 25). Numerical effect sizes and correlation values were omitted from the abstract.
Cited by
- supports There are approximately 11 different opportunistic bacterial types in periodontal pockets, including spirochetes and P. gingivalis, that require a dark, low-oxygen environment to multiply.