Streptococcus agalactiae is an unusual pathogen in adults who are not pregnant. S agalactiae endocarditis is a poorly defined entity because it is uncommon; in contrast to other streptococcal endocarditis, it bears a high mortality rate. The aim of this study was to define its clinical, prognostic, and therapeutic profile on the basis of a series of 9 consecutive patients.

We conducted a prospective and multicenter study of patients with infectious endocarditis in which 310 episodes were included.

S agalactiae grew in 9 patients (3%) who had no valve prosthesis. All patients except 1 had underlying diseases, and all patients had serious complications; the most common complications were major emboli, heart failure, and shock. The valve affected was the mitral valve in 4 patients, the aortic valve in 2 patients, both the mitral and aortic valves in 2 patients, and the tricuspid valve in 1 patient. All episodes were on native valves. Vegetations tended to be large (maximal diameter >10 mm in all patients), very mobile, and pedunculated. An abscess was found in 2 patients, and a perforation of the valve developed in 3 patients. Five patients died (mortality rate, 56%), 3 of whom had received antibiotic therapy alone. The 4 patients who survived underwent combined medical-surgical therapy.

S agalactiae native valve endocarditis is very aggressive, and early surgery should be considered to prevent the destruction of valves and development of serious complications.