Associations between microbial species in subgingival plaque samples

Authors: S.S. Socransky, A.D. Haffajee, J.L. Dzink, J.D. Hillman — The Forsyth Dental Center, Boston, MA

Journal: Oral Microbiology and Immunology | Published: 1988 | Vol. 3: 1–7

Abstract

Samples of subgingival plaque were taken from 275 active and inactive sites in 35 subjects with destructive periodontal diseases. The predominant cultivable microbiota was determined in each of the samples by characterizing 50 randomly selected isolates. Microbial associations between species were determined by computing the odds ratio of a site being infected by a "target" species in the presence of an "effector" species.

Data are presented for 22 numerically dominant "effector" species and 8 "target" species consisting of suspected periodontal pathogens, including Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Bacteroides gingivalis, Bacteroides intermedius, Peptostreptococcus micros, Streptococcus intermedius, and Wolinella recta.

In general, species of streptococci, an unnamed Actinomyces sp., and Propionibacterium acnes showed a negative association with the 8 suspected pathogens, while many Gram-negative species tended to show a positive association with these suspected pathogens.

Key Findings

There appeared to be specificity in the associations observed. S. sanguis II, S. uberis, P. acnes, Capnocytophaga ochracea, and an unnamed Actinomyces sp. showed negative associations with 4 of the suspected periodontal pathogens, while B. gingivalis, Fusobacterium nucleatum, and the Eubacterium sp. showed only positive or neutral associations with the target species.

For example, the presence of S. sanguis II in a site substantially reduced the odds of detecting A. actinomycetemcomitans — and this negative association became stronger as the proportion of S. sanguis II in the site increased.

Significance

This landmark study provides foundational evidence that microbial associations play a critical role in controlling the composition of subgingival plaque and determining periodontal health outcomes. The data demonstrate that the same streptococcal species incorporated into ProBiora3® — including S. uberis and S. sanguis — are naturally antagonistic to key periodontal pathogens. Understanding these associations is essential to the rationale for probiotic-based approaches to periodontal health maintenance.