Sulfate-reducing bacteria in periodontal pockets and in healthy oral sites

The aim of this study was to monitor the presence of sulfate-reducing bacteria (SRB) at different sites in the mouths of both healthy individuals and periodontitis patients. In 20 healthy subjects and 21 periodontitis patients, samples were taken from the palate, vestibulum, dorsum of the tongue, supragingival plaque, and periodontal pockets. In order to demonstrate growth of SRB, samples were incubated in an anoxic chamber in a reduced growth-medium for SRB, with an iron-indicator for sulfide production. The SRB were detected throughout the oral cavity. They were found on the mucosa in 10% of both healthy subjects and periodontitis patients. On the tongue and in supragingival plaque, the frequency of detection was slightly higher (22% of the subjects). In contrast, 86% of the periodontitis patients harbored SRB in one or more pockets. In 1/3 of the patients, SRB were present in all 3 pockets that were sampled. The data indicated that SRB belong to the normal oral microbiota, and have a preference for periodontal pockets.