High Frequency of Enteric Bacteria in the Subgingival Biofilm

Objectives: Background and Aim: The complex and diverse subgingival biofilm may be a reservoir for species not commonly considered as bacterial residents of the oral microbiota. This study aimed to determine the prevalence and levels of microorganisms that colonize the GI tract in the subgingival microbiota of individuals with various periodontal conditions.
Methods: Methods: Subgingival plaque samples were obtained from 633 patients with periodontal health (H, 137), gingivitis (G, 77), chronic (CP, 317) and aggressive periodontitis (AP, 102), and analyzed for the presence and counts of enteric Gram-negative rods, Salmonella enteric typhi, Serratia spp., Clostridium difficile, Enterococcus faecalis, Helicobacter pylori, Aggregatibacter actinomycetemcomitans and the red complex members by the checkerboard method. Associations with smoking, gender, age and periodontal status were examined by Chi-square, Mann-Whitney and Spearman correlation tests.
Results: All GI tract bacteria were detected in high prevalence (≥30%) in the subgingival plaque, similar to the frequency of oral species, although their levels were lower than the levels of periodontal bacteria. Significant differences among clinical groups were seen only for periodontal pathogens. Enteric Gram-negative rods, E. faecalis, and H. pylori were more frequently detected in males (p<0.05), whereas H. pylori and C. difficile were found in higher prevalence and/or levels in smokers (p<0.05). Significant but very modest positive correlations were observed between periodontal inflammation, probing pocket depth, presence of supragingival plaque and Enteric Gram-negative rods and E. faecalis (rho 0.106 to 0.155, p<0.01). S. enteric typhi (rho=-0.188) and Serratia spp. (rho=-0,165) presented negative associations with supragingival plaque (p<0.01).
Conclusions: Conclusions: Bacterial colonizers of the GI tract microbiota are detected in high frequency as periodontal pathogens in the subgingival biofilm, although no marked associations between these species and clinical periodontal status were found.