Sulfate-reducing bacteria in relation with other potential periodontal pathogens.

Background, aims: Oral sulfate-reducing bacteria are involved in several clinical categories of periodontitis. The aim of this cross-sectional study was to compare the presence of sulfate-reducing bacteria (SRB) with other putative pathogens including spirochetes, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, and Treponema denticola in periodontal lesions. Method: Periodontal SRB were detected by enrichment culture and compared with a microscopic spirochete count (n=168). Species-specific oligonucleotide probes directed against the 16S rRNA were employed to determine the presence of A. actinomycetemcomitans, P. gingivalis, B. forsythus, and T. denticola (n=55). Results: A significant positive correlation was observed between the presence of SRB and the proportions of spirochetes in subgingival plaque, although the 2 bacterial groups also occurred separately. SRB tended to be negatively correlated with the presence of A. actinomycetemcomitans. In contrast, all pockets with SRB harbored either T. denticola, or both T. denticola and B. forsythus (12/14) before therapy. Interestingly, the combination of SRB with P. gingivalis occurred in 32% of the periodontal pockets before treatment. After initial periodontal therapy, the prevalence of this combination was reduced to 2% of the sites, and to 25% of the sites in recall patients. Conclusion: The presence of SRB was positively correlated with T. denticola, B. forsythus, and P. gingivalis in periodontal lesions. These suspected pathogens form a complex strongly associated with destructive periodontitis.