Viridans streptococci

Viridans streptococci are Gram-positive, spherical bacteria of the genus Streptococcus. Colloquially, the bacteria are also referred to as Streptococcus viridans (lat. viridans: greening), "greening streptococci", because they can be detected on blood agar plates as a result of alpha-hemolysis ("greening"). This is a group of numerous different Streptococcus species.

Viridans streptococci primarily cause infections of the oral cavity, but can also cause more severe infections if they enter the bloodstream. The pathogens cause the following diseases, among others:

  • Caries

  • Gingivitis (inflammation of the gums)

  • Periodontitis (inflammation of the periodontium)

  • Abscesses

  • Bacteremia (bloodstream infection)

  • Endocarditis lenta (inflammation of the cardiac wall/valves with gradual deterioration)

  • Sepsis

Viridans streptococci occur naturally in the mouth and throat, which is why they are also referred to as “oral streptococci”. However, they are also present in the gastrointestinal tract and in the vagina.

Relevance of pathogen in transmission in endoscopy

  • Gastroenterology: Low

  • Pulmonology: Low

  • Ear, nose, and throat: Low

  • Urology: Low

Relevance for endoscope surveillance

  • Low or moderate concern organism

Transmission route

Transmission is endogenous (self-infection) or via secretion contact.

Resistance to antibiotics

Reduced sensitivity has been described to penicillins, cephalosporins and sulfonamides, among others.

Sources and further readings

  1. Gries O, Ly T: Infektologie – Kompendium humanpathogener Infektionskrankheiten und Erreger, Springer-Verlag Berlin Heidelberg 2019.

  2. Gatermann S et al. In: Hahn H, Kaufmann S, Schulz T, Suerbaum S. (Hrsg.): Medizinische Mikrobiologie und Infektiologie, 6. Auflage, Springer Verlag, Heidelberg 2009.

  3. Kovaleva J et al. Transmission of Infection by Flexible Gastrointestinal Endoscopy and Bronchoscopy,, Clin Microbiol Rev. 2013 Apr; 26(2): 231–254.

  4. Zuccaro G Jr et al. Viridans streptococcal bacteremia after esophageal stricture dilation, Gastrointest Endosc. 1998 Dec;48(6):568-73.