Clinical significance of bacteremia involving the "Streptococcus milleri" group: 51 cases and review.

Fifty-one cases of bacteremia due to the "Streptococcus milleri" group were analyzed. Among these were 40 patients with underlying diseases, and associated local infections were present in 27 patients. The most frequent sites of infection were the thoracic cavity and the digestive and hepatobiliary tracts. A probable portal of entry related to mucosal-barrier trauma was identified for an additional 16 patients. The origin of bacteremia was unknown for the remaining eight patients. Abscess formation was evident for only six patients, and there were no cases of endocarditis. Multiple positive blood cultures and polymicrobial bacteremia were associated significantly with the presence of local sites of infection. The most common causative species were Streptococcus anginosus and Streptococcus constellatus. Two patients died of bacteremia.