A case of Escherichia coli native mitral valve endocarditis complicated by annular abscess and central retinal artery occlusion.

Infective endocarditis (IE) is most frequently caused by gram-positive organisms such as Staphylococci, Streptococci, and Enterococci. IE due to gram-negative organisms is uncommon and is most often associated with the HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella) of organisms. IE due to other gram-negative organisms such as Escherichia coli (E. coli) is rare and less is known about its natural pathology. Valvular abscesses due to E. coli IE have been described, however these are not usually reported in a native mitral valve. Here we describe the case of a 69 year old female who initially presented with pyelonephritis and was found to have E. coli IE of the posterior mitral valve leaflet associated with a large annular abscess, which ultimately led to septic emboli causing stroke and central retinal artery occlusion (CRAO), an extremely rare sequela of IE. Definitive diagnosis and mitral valve replacement were delayed by a low initial suspicion for IE, as well as complications including pulmonary decompensation and incidental discovery of a mycotic aneurysm of the left anterior cerebral artery.