Materials and Methods Conclusions Acknowledgements • Background: Group D streptococci (GDS) are indigenous in the gastrointestinal tracts of humans and animals. Currently, S. bovis, the most common GDS, has been re-classified into 4 different species (Streptococcus gallolyticus, Streptococcus pasteurianus, Streptococcus infantarius and Streptococcus lutetiensis). However, clinical characteristics and the association between gastrointestinal diseases and these species have not been well studied. The objective of this study is to investigate the clinical characteristics of patients with GDS bacteremia. • Methods: We conducted a retrospective review of adult patients with GDS bacteremia who were hospitalized at Siriraj Hospital between 1 January 2009 and 30 June 2011. Clinical characteristics including predisposing factors and microbiological data were analyzed. • Results: One hundred and forty-seven episodes of bacteremia caused by GDS were included. Seventy-eight patients (58.2%) were male. Patients’ mean age was 63 years. Of 147 GDS isolates, 134 (91.2%) were identified as S. pasteurianus, 6 (4.1%) were S. gallolyticus, 2 (1.4%) were S. infantarius, 1 (0.7%) was S. lutetiensis and 4 isolates (2.7%) were unidentifiable. Cirrhosis was identified as underlying disease in 87 patients (59.2%). Eighty-three patients (56.5%) had primary bacteremia and 49 patients (33.3%) had secondary bacteremia from spontaneous bacterial peritonitis. Thirty patients (20.9%) underwent colonic evaluation and colonic polyps were the most common finding found in 8 patients. Colonic cancer was diagnosed in 5 patients with GDS bacteremia in which 4 of 5 patients were diagnosed previously and before the bacteremic episodes. Bacteremia due to S. pasteurianus was associated with patients who had cirrhosis (p = 0.041), whereas S. gallolyticus was more likely to be associated with non-cirrhotic patients (p = 0.031). Overall mortality of patients with GDS bacteremia was 22%. • Conclusion: S. pasteurianus was the most common species isolated in patients with GDS bacteremia and is associated with chronic liver disease. • Group D streptococci (GDS) are indigenous in the gastrointestinal tracts of humans and animals. The association between bacteremia caused by Streptococcus bovis (the most common species of GDS) and colonic malignancies has been documented. Currently, S. bovis has been re-classified into 4 different species (Streptococcus gallolyticus, Streptococcus pasteurianus, Streptococcus infantarius and Streptococcus lutetiensis). The prevalence and clinical characteristics of infections caused by different GDS species and the association between gastrointestinal lesions and those species has not been well studied. • S. pasteurianus was the most common species isolated in patients with GDS bacteremia. GDS infection was significantly associated with liver diseases including cirrhosis and hepatocellular carcinoma. S. pasteurianus is likely to be linked to colon cancer, especially in those without chronic liver diseases. Our study suggested that patients with S. pasteurianus bacteremia who do not have cirrhosis should be appointed for colonic evaluation and considered to search for endocarditis. Finally, beta-lactam antibiotic, especially penicillin, should be used as a drug of first choice for treatment of GDS bacteremia. • We thank the staffs of Department of Microbiology for their collaborations and Ms. Khemajira Karaketklang, Department of Medicine, Siriraj Hospital for assistance of data analysis. Poster number 831