Clinical Significance of Bacteremia Caused by Viridans Streptococci

ABSTRACT

BACKGROUND: Clinical significance of viridans streptococcal bacteremia may be variable from insignificant colonization to serious invasive diseases such as endocarditis. However, there have been no data on the clinical implications of viridans streptococcal bacteremia in Korea to date. MATERIALS AND METHODS: We have analyzed 95 cases of viridans streptococcal bacteremia diagnosed at the Samsung Medical Center from 1997 to 2003. All available clinical and microbiological data were analyzed. RESULTS: Of the total 95 cases, 76 (80%) had clinically significant infections, while 20% of cases were not associated with clinical diseases. Primary bacteremia was the most common disease (48%) followed by intra-abdominal infections (15%), and infective endocarditis (8%). Primary bacteremia was mostly observed in patients with neutropenia after anti-cancer chemotherapy. Infective endocarditis was unlikely if patients did not have underlying heart diseases. S. mitis, S. oralis, and S. intermedius were the most common etiologic agent in infective endocarditis, primary bacteremia, and intra-abdominal infection, respectively. Thirty-eight percent of isolates were not susceptible to penicillin. CONCLUSION: Viridans streptococcal bacteremia is likely to be associated with invasive clinical diseases, especially in patients with neutropenia, intra-abdominal diseases or underlying heart diseases. However, the presence of viridans streptococci in the blood cultures does not necessarily mean the possibility of infective endocarditis.