Viridans Group Streptococci

Snapshot

• A 32-year-old man presents to his primary care physician for a wellness examination. He reports to currently feeling well; however, he notices severe discomfort and pain in his mouth. He denies any trauma to the area but endorses infrequently brushing his teeth. Medical history is significant for a ventricular septal defect that has not required repair. Physical examination is remarkable for dental caries leading to pulpitis. He is referred to a dentist for immediate dental care. Prior to tooth extraction, he will require prophylactic amoxicillin.

Introduction

• Classification
  • gram-positive, optochin-resistant α-hemolytic cocci 
    • Streptococcus mitis
    • S. sanguis
    • S. mutans
• Reservoir
  • normal flora of the oropharynx and live in close association with the teeth and gingiva
• Microbiology
  • transmission
    • endogenous
  • reservoir
    • normal flora of oropharynx
  • molecular biology
    • biofilm mediates adherence to
      • heart valve
      • tooth enamel
    • forms vegetations
    • dextran mediated
      • dextran is an insoluble polysaccharide synthesized from glucose that allows the bacteria to adhere to surfaces 
      • requires pre-existing local deposition of fibrin for adherence
• Pathogenesis
  • transient viridans streptococcal bacteremia
    • caused by eating, toothbrushing, flossing, or any other cause of minor trauma to the oropharynx
  • dental caries
    • localized dental hard tissue destruction caused by bacteria containing the ability to produce acid and grow in acidic environments such as S. mutans and S. mitis
  • periodontal disease
    • microorganisms in the subgingival dental plaque penetrate the gingival epithelium, leading to a host inflammatory response, damaging the periodontium
  • endocarditis
• manipulation of the gingiva or periapical region of the oral mucosa (such as in dental procedures) can lead to bacteremic seeding of the heart valves and prosthetic devices such as in S. sanguinis

Presentation

• Odontogenic infections (e.g., dental caries, gingivitis, and periodontitis)
  • symptoms
    • pain and discomfort
  • physical exam
    • pits and fissures on tooth surfaces and staining of teeth
    • discolored defect on tooth surfaces
    • gingival swelling
• Endocarditis 
  • symptoms
    • chills
    • anorexia
    • weight loss
    • patients may have tooth pain or related symptoms
  • physical exam
    • fever
• new heart murmur

Studies

• α-hemolytic growth pattern
• Optochin resistant
• differentiates from S. pneumoniae, which is also α-hemolytic but optochin sensitive

Differential

• Other causes of endocarditis
  • S. aureus
• catalase-positive, coagulase-positive, gram-positive cocci

Treatment

• Medical
  • antibiotic prophylaxis
    • indication
      • administered in patients undergoing dental procedures who are 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
    • medications
      • amoxicillin
• treatment of choice

Complications

• Sepsis
• Abscess