Peptostreptococcus species are commensal organisms in humans, living predominantly in the mouth, skin,
gastrointestinal, and urinary tract, and compose a portion of the bacterial gut flora. Under immunosuppressed or
traumatic conditions these organisms can become pathogenic, as well as septicemic. Peptostreptococcus can cause
brain, liver, breast, and lung abscesses, as well as generalized necrotizing soft tissue infections.[2]
http://encyclopedia.thefreedictionary.com/Peptostreptococcus
PEPTOSTREPTOCOCCUS: P. magnus is the species that is most often isolated from infected sites. they can cause
infections of bones, joints and soft tissue. Their increasing resistance to such antibiotics as penicillin G and
clindamycin makes them especially important to clinical work.