Definition:

The viridans group streptococci (VGS), a heterogenous group of streptococcal species, are the predominant species of the human oral flora and commonly inhabit other areas of the upper respiratory, gastrointestinal, and female genital tracts. VGS are usually organisms of low virulence. However, VGS are a major cause of sepsis and pneumonia in neutropenic individuals, and an important cause of sepsis and meningitis in neonates. These organisms are also occasional pathogens in healthy children and adults, causing infections such as subacute endocarditis. Although VGS resistance to penicillin and the macrolide-lincosamide-streptogramin B (MLS) drugs is an evolving problem, several drugs remain uniformly active against the VGS. Thus far, VGS resistance to vancomycin, linezolid, and daptomycin remains extremely rare.