Rare Simultaneous Left and Right-Sided Native Valve Infective Endocarditis Caused by Rare Bacterium

Simultaneous left and right-sided native valve infective endocarditis (IE) is rare. Staphylococcus aureus was the predominant organism for bilateral IE. Shunt diseases are common risk factors of both-sided IE. Streptococcus anginosus (S. anginosus) is usually associated with pyogenic infections, but rarely a cause of IE. Here we present an extremely rare case of simultaneous left and right-sided native valve IE affecting the mitral and tricuspid valves caused by S. anginosus in an adult patient that has not been reported in the literature previously, particularly without the most frequent predisposing factors of IE. A 66-year-old man was admitted due to generalized fatigue, chills, malaise, and intermittent fevers for 1 year. A grade III-IV/VI systolic murmur at the mitral area and a III/VI systolic murmur at the tricuspid area were noted on physical examination. Laboratory evaluation revealed an elevated erythrocyte sedimentation rate and C-reactive protein level, and high fasting blood glucose. Blood culture was positive for S. anginosus. Echocardiography revealed vegetations in both sides of the heart: a large mitral valve vegetation with severe mitral regurgitation, as well as another vegetation on the tricuspid valve with moderate regurgitation. The case highlights a rare pathogen of both-sided IE, a rare presentation of S. anginosus infection, and several points worthy of note in echocardiography of IE.