Thiocyanate as a cofactor in myeloperoxidase activity against Streptococcus mutans

Inhibition of glycolysis of some oral bacteria was established in vitro by an antibacterial system, consisting of myeloperoxidase, H2O2, and a cofactor. When thiocyanate was used in physiological concentration as a cofactor, the system acted (at low pH) bactericidally on Streptococcus mutans, as indicated by the determination of viable counts. However, at neutral pH, the glycolysis of Streptococcus mutans was inhibited, while its viability remained unaffected. The possible role of such a pH-dependent antibacterial system in the oral cavity is discussed.