Streptococcus bovis endocarditis: Update from a multicenter registry

Background Infective endocarditis (IE) due to Streptococcus bovis has been classically associated with elderly patients, frequently involving >1 valve, with large vegetations and high embolic risk, which make it a high-risk group. Our aim is to analyze the current clinical profile and prognosis of S bovis IE episodes, in comparison to those episodes caused by viridans group streptococci and enterococci. Methods We analyzed 1242 consecutive episodes of IE prospectively recruited on an ongoing multipurpose database, of which 294 were streptococcal left-sided IE and comprised our study group. They were classified into 3 groups: group I (n = 47), episodes of IE due to S bovis; group II (n = 134), episodes due to viridans group streptococci; and group III (n = 113), those episodes due to enterococci. Results The incidence of enterococci IE has significantly increased in the last 2 decades (6.4% [1996-2004] vs 11.1% [2005-2013]; P = .005), whereas the incidence of IE due to S bovis and viridans streptococci have remained stable (4% and 10%, respectively). Gender distribution was similar in the 3 groups. Patients with S bovis and enterococci IE were older than those from group II. Nosocomial acquisition was more frequent in group III. Concerning comorbidity, diabetes mellitus (36.7% vs 9.2% vs 26.8%; P < .001) was more common in groups I and III. Chronic renal failure was more prevalent in patients from group III (4.2% vs 1.5% vs 19%; P < .001). Prosthetic valve IE was more frequent in enterococcal IE. Infection upon normal native valves was more frequent in S bovis IE. Colorectal tumors were found in 69% of patients from this group. Vegetation detection was similar in the 3 groups. However, vegetation size was smaller in S bovis IE. During hospitalization, in-hospital complications and in-hospital mortality were higher in enterococci episodes. Conclusions S bovis IE accounts for 3.8% of all IE episodes in our cohort; it is associated with a high prevalence of colonic tumors, with predominance of benign lesions, and affects patients without preexisting valve disease. It is related to small vegetations and a low rate of in-hospital complications, including systemic embolisms. In-hospital mortality is similar to that of viridans group streptococci.