Streptococcus Viridans Group

Aka: Streptococcus Viridans Group, Viridans Streptococcus, Viridans Group Streptococci, Streptococcus Mutans, Streptococcus Mitis, Streptococcus Salivarius, Streptococcus Anginosus, Streptococcus Milleri, Streptococcus Intermedius

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II. Pathophysiology

  1. Streptococcus Viridans are a heterogeneous group
    1. Alpha-hemolytic Streptococcus (Gram Positive Cocci)
    2. Viridans is named for the greenish glow on Blood Culture media (alpha-hemolytic effects on RBCs)
    3. Subdivided into at least 4 sub groups (see below)
  2. Normal human colonization
    1. Gastrointestinal Tract
    2. Oropharynx
  3. Human Infections
    1. Subacute Bacterial Endocarditis
      1. Extracellular Dextran allows binding to Heart Valves (Streptococcus Viridans, Group D Strep, Enterococcus)
    2. Dental Infections (esp. Streptococcus Mutans)
      1. S. mutans binds teeth and ferments sugars to acids, leading to dental decay
    3. Abscesses
      1. Streptococcus Anginosus Group (intermedius) are normal, microaerophilic flora in the Gastrointestinal Tract
      2. Brain and Liver Abscesses
        1. Streptococcus Anginosus Group either alone or in mixed Bacterial Infections with Bacteroides
        2. Patients may present with Occult Bacteremia

III. Types

  1. Streptococcus Mutans Group
    1. Streptococcus Mutans
    2. Streptococcus sobrinus
    3. Streptococcus criceti
    4. Streptococcus rattus
    5. Streptococcus downei
    6. Streptococcus macacae
  2. Streptococcus Mitis Group
    1. Streptococcus Mitis
    2. Streptococcus sanguis
    3. Streptococcus parasanguis
    4. Streptococcus gordonii
    5. Streptococcus crista
    6. Streptococcus infantis
    7. Streptococcus oralis
    8. Streptococcus peroris
  3. Streptococcus Salivarius Group
    1. Streptococcus Salivarius
    2. Streptococcus vestibularis
    3. Streptococcus thermophilus
  4. Streptococcus Anginosus Group (Streptococcus Milleri Group, Intermedius group)
    1. Streptococcus Anginosus
    2. StreptococcusConstellatus
    3. Streptococcus Intermedius

IV. References

  1. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 31-2
  2. Doern (2010) J Clin Microbiol 48(11):3829-35 +PMID: 20810781 [PubMed]

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