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.