Streptococcus milleri group (Streptococcus anginosus): recovery from intra-abdominal and soft tissue sites.

One hundred thirty-three Streptococcus milleri group (S. anginosus) isolates were recovered from 487 surgical patients. The streptococci were recovered from 33 percent of intra-abdominal infection cultures (84/257). 22 percent of samples from penetrating visceral trauma (19/86), 52 percent of perirectal abscess specimens (13/25), 13 percent of nonpuerperal breast abscess cultures (8/60), and 15 percent of diabetic foot lesions (9/59). Ninety-eight percent of the S. milleri (131/133) were recovered as companion flora in polymicrobial cultures. The organisms were highly susceptible to the beta-lactam antibiotics. The precise pathogenic role of the S. milleri group (S. anginosus) is unknown. However, intrinsic virulence may be expressed in patients with severe infection or other predisposing factors.