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Strep viridans

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Strep viridans 

  • Characteristics
    • Gram + cocci
    • Catalase -
      • Determines staph (catalase positive) vs. strep 
    • Alpha-hemolytic
    • Bile-resistant
      • No cell lysis in bile
      • Helps differentiate vs. Strep pneumoniae (bile-sensitive)
    • Optochin-resistant
      • differentiates them from Strep pneumoniae (optochin-sensitive)
  • Presentation
    • normal flora of the oral cavity
      • Transient bacteremia usually occurs after dental work
    • dental caries/cavities
      • Adheres to tooth enamel via biofilm
    • Endocarditis on damaged heart valves
      • most common etiologic agent in subacute bacterial endocarditis (SBE) following dental work
      • Pre-existing valvular abnormality (e.g. rheumatic heart disease, congenital malformations) required since adherence by biofilm requires pre-existing fibrin deposition
      • Contrast to Staph aureus, which binds to normal heart valves 
  • Treatment
    • Antibiotic prophylaxis
      • Administered in patients undergoing dental procedures who are at the highest risk of developing bacterial endocarditis
        • Prosthetic heart valves
        • Prior history of infective endocarditis
        • Unrepaired cyanotic congenital heart disease
        • structurally abnormal valve in a transplanted heart
      • Amoxicillin is treatment of choice