Clinical characteristics and significance of Streptococcus salivarius bacteremia and Streptococcus bovis bacteremia:: a prospective 16-year study

The aim of this study was to determine the clinical significance of Streptococcus salivarius isolates recovered from blood cultures and compare them with isolates of Streptococcus bovis biotypes I and II. Seventeen of the 52 (32%) S. salivarius isolates recovered were considered clinically significant, compared with 62 of the 64 (97%) S. bovis isolates (p < 0.0001). Bacteremia caused by S. salivarius occurred mostly in patients who showed relevant disruption of the mucous membranes and/or serious underlying diseases. Patients with S. salivarius bacteremia were younger than those with S. bovis bacteremia (57 vs. 67 years; p < 0.01). Patients with S. salivarius bacteremia and patients with S. bovis II bacteremia had similar rates of endocarditis, colon tumors, and noncolon cancer. On the other hand, when compared with S. bovis I bacteremia, S. salivarius bacteremia was associated with lower rates of endocarditis (18% vs. 74%, respectively) (p < 0.01) and colon tumors (0% vs. 57%, respectively) (p < 0.005) and higher rates of noncolon cancer (53% vs. 9.5%, respectively) (p < 0.01). Bacteremia caused by S. bovis II had a hepatobiliary origin in 50% of the patients, while, in contrast, that due to S. salivarius or S. bovis I was less frequently associated with a hepatobiliary origin (12% and 5%, respectively) (p < 0.00001). The rate of penicillin resistance was 31% among S. salivarius isolates and 0% among S. bovis isolates (p < 0.0001). In conclusion, the clinical characteristics of S. salivarius bacteremia and S. bovis II bacteremia are similar, and the isolation of S. salivarius in blood should not be systematically regarded as contamination.