Antimicrobial effect of acidified nitrite on periodontal bacteria

The antimicrobial agent nitric oxide (NO) is formed in the mouth and its co ncentration is directly related to salivary nitrite, which in turn is relat ed to dietary nitrate intake. The aim of this study was to determine whethe r nitrite under acidic conditions will have an inhibitory effect, possibly occurring through NO production, on the periodontal disease pathogens Fusob acterium nucleatum, Eikenella corrodens and Porphyromonas gingivalis. Where as the growth of these organisms was inhibited by a more acid pH, the addit ion of nitrite caused a marked, further dose-dependent reduction in bacteri al numbers after exposure. The ability of these bacteria to recover from ni trite exposure was also affected by pH and nitrite concentration. At acidit y levels below pH 5.0, low concentrations of nitrite (0.2 mM) caused effect ive complete killing of the periodontal bacteria. Addition of sodium thiocy anate did not increase the bacteriostatic or bacteriocidal activity of acid ified nitrite against any of the 3 bacteria. These results demonstrate the possibility that nitrite in saliva, under appropriate conditions, may have an effect on the growth and survival of the bacteria implicated in periodon tal disease.