Oral Streptococci

Most of the oral streptococci of the type often known as the viridans group have no group antigen. They usually cause a-hemolysis, some y-hemolysis as well.

Oral streptococci are responsible for 50-70% of all cases of bacterial endocarditis, overall incidence of which is one to two cases per 100 000 annually. The origins of endocarditis lie in invasion of the vascular system through lesions in the oral mucosa. A transitory bacteremia results. The heart valves are colonized and a biofilm is formed by the organism. Predisposing factors include congenital heart defects, acute rheumatic fever, cardiac surgery, and scarred heart valves. Laboratory diagnosis of endocarditis involves isolation of the pathogen from blood cultures. Drug therapy of endocarditis is carried out with either penicillin G alone or combined with an aminoglyco-side (mostly gentamicin). Bactericidal activity is the decisive parameter.

— Pronounced Dental Caries

— Pronounced Dental Caries

Fig. 4.6 Certain oral streptococci (S. mutans) are the main culprits in tooth decay.

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