[Bacterial antagonism of oral secretions towards staphylococci]

Bacterial antagonism may be one of the mechanism which regulates the bacterial flora of the pharynx. We have investigated the bacterial antagonism exerted in oral secretion by alpha-hemolytic streptococci against S. aureus and S. epidermidis. We cultured viridans streptococci and staphylococci in human saliva and we noted a bactericidal activity towards staphylococci. Such activity, referable to the salivary system (peroxidase-thiocyanate) activated by hydrogen peroxide produced by streptococci, was greater on S. epidermidis. The remarkable sensitivity of S. epidermidis could explain the rare presence of this species in pharynx and oral cavity.