Streptococcus mitis

Background

• Part of the normal flora of the oropharynx, female genital tract, gastrointestinal tract, and skin

Microbiology

• A groups of gamma-hemolytic catalase-negative Gram-positive coccus within the genus Streptococcus
  • Includes Streptococcus mitis and Streptococcus oralis
• On Gram stain, often has an arrow-head shape and grows in pairs or short chains
• Negative for acetoin production, arginine, esculin, and mannitol and are sorbitol fermentation negative
• Closely related to Streptococcus pneumoniae

Clinical Manifestations

• Generally low virulence
• Invasive disease is much more common in immunocompromised patients, especially neutropenic patients and those undergoing chemotherapy
• Can cause bacteremia, infective endocarditis, dental caries, eye infections, meningitis, and pneumonia