Bacteremic community-acquired pneumonia due to viridans group streptococci.

We studied 1118 patients with community-acquired pneumonia who were admitted to our hospital over an 8-y period. Seventy-six of the 1118 patients were bacteremic and 7 (9.2%) of these had blood cultures positive for various viridans streptococci. Four had polymicrobial bacteremia (S. mitis, S. sanguis 1, S. sanguis II; S. mitis, S. sanguis II; S. MG; S. sanguis II, Neisseria sp; S. intermedius, S. aureus). For 3 of the 7, viridans streptococci were the only agents implicated in the etiology of the pneumonia. These patients were classified as definite viridans streptococcal pneumonia; the remaining 2 were probably and 2 were possibly due to these micro-organisms. The 5 males and 2 females had a mean age of 61.8 y. The mortality rate was 28%. All were febrile and had elevated white blood cell counts. The 5 who had arterial blood gas measurements performed were hypoxemic pO2 34-68 torr. The chest radiographs were not distinctive--a segmental alveolar opacity was the most common abnormality. We conclude that viridans streptococci rarely cause bacteremic community-acquired pneumonia. There are no distinctive clinical or radiographic features of this type of pneumonia.