Viridans streptococci

Streptococcus viridans is a pseudotaxonomische term for a large group of generally non-pathogenic streptococci.

Streptococcus viridans is a Gram-positive spherical bacterium, which is how most streptococci chains. On Blood Agar plates its colonies form a viridans (Latin viridans: Greening ) yard and are therefore referred to as α - hemolytic. Streptococcus viridans species occur in the mouth and throat. They are the most common germ in the case of slowly progressing heart wall inflammation ( endocarditis lenta ). The subgroup Str mutans is responsible for caries, very rarely call viridans streptococcal meningitis forth.

Differentiators to other streptococci

Streptococcus viridans and Streptococcus pneumoniae can be differentiated with an optochin test, as S. viridans is optochin - resistant. However Str pneumoniae diplococci are, strictly speaking, the pathogenic forms are typically bekapselt. Str viridans has no polysaccharide capsule. Similarly, the C antigen is absent ( Lancefield antigen) of St. pyogenes group ( = group A streptococci ), the Str agalactiae ( = group B streptococci ) and enterococci ( = group -D streptococci ).

The organisms occur frequently in the mouth before, and Streptococcus mutans is the causative agent of dental caries. Other representatives may be involved in the oral cavity infections. When they enter the bloodstream, they can cause endocarditis, especially in people with heart valve damage.

Str viridans is also about 50-70 % the most common cause of bacterial endocarditis.

Occurrence

• Ear, nose and throat area
• Mouth
• Skin

Diagnosis

The diagnosis of endocarditis is based on echocardiography ( TEE). A microbiological diagnosis by blood culture should be performed on three independent samples provided

Therapy

Depending on the symptoms, different antibiotics are used, Str viridans is always sensitive to penicillin, in bacterial endocarditis, however, always first treated empirically until a definitive pathogen detection is optionally available with antibiogram.

Prophylaxis

Prophylaxis against bacterial endocarditis is seen only in a few patients as useful. (see endocarditis)

References and sources

• Bacteriology