Viridans group streptococci

Background

Microbiology

• Gram-positive cocci
• Commensal oral flora

Species

• Streptococcus anginosus group (previously milleri group): most likely to cause invasive pyogenic infections similar to Staphylococcus aureus
  • Streptococcus anginosus
  • Streptococcus intermedius
  • Streptococcus constellatus
• Streptococcus mitis group
  • Streptococcus mitis
  • Streptococcus oralis
• Streptococcus sanguinis group
  • Streptococcus gordonii
  • Streptococcus sanguinis
  • Streptococcus parasanguinis
• Streptococcus salivarius group
  • Streptococcus salivarius
  • Streptococcus vestibularis
  • Streptococcus thermophilus
• Streptococcus mutans group
  • Streptococcus mutans

Management

• Penicillin non-susceptibility varies by species
  • S. salivarius group is 80% non-susceptible (in Korea)
  • S. mitis group is 60%
  • S. sanguinis group is 40%
  • S. anginosus group is 6%

Further Reading

• It’s Not Easy Being Green: the Viridans Group Streptococci, with a Focus on Pediatric Clinical Manifestations. J Clin Microbiol. 2010;48(11):3829-3835. DOI: 10.1128/JCM.01563-10