Viridans Streptococci

Categorization
Cell Wall: Gram Positive Shape: Cocci
Biochemistry: Catalase Negative Metabolism: Microaerophilic
Streptococcal subclassification: No Lancefield Antigen, alpha-hemolytic
Optochin resistance used to distinguish from S. pneumonia
Definition
  • Viridans Streptococci are a grouping of multiple Streptococcal species which do not possess Lancefield antigens, are alpha-hemolytic, and result in infective endocarditis.
Clinical Consequences
  • Dental Carries
    • Some species are part of the normal oral flora and bind teeth avidly. Through fermentation of sugars, high local acidity is generated, thus resulting in cavities.
  • Infective Endocarditis
    • Viridans Streptococci may produce infective endocarditis usually of the 'subacute' subtype. Briefly, this may manifest as fever, new heart heart murmurs, and petechia. Organisms may gain access to the blood stream following dental procedures or vigorous tooth brushing.
  • Abscess Formation
    • A particular subset of Viridans Streptococcal species can produce abscesses in a variety of organs but especially in the brain and abdomen.
Treatment