Streptococcus agalactiae infective endocarditis with large vegetation in a patient with underlying protein S deficiency.

We present a case of a patient with underlying protein S deficiency who suffered from infective endocarditis with a large anterior mitral leaflet (AML) mass of approximately 4.5 cm in length. Intraoperative transesophageal echocardiography (TEE) revealed the mass at the AML base and a rupture of the posterior mitral leaflet chordae tendinae. The vegetation's large size may have been caused by one or more of three factors: location, underlying disease, and the microorganism causing infection. Patients with protein S deficiency are prone to thromboembolic events during cardiac surgery. Infective endocarditis caused by Streptococcus agalactiae usually has a poor prognosis, and, thus, early surgery is recommended.