Culture-negative infective endocarditis of the aortic valve due to Aerococcus urinae: a rare aetiology.

Bacteria of the species Aerococcus urinae are Gram-positive, catalase-negative cocci that are arranged in pairs, tetrads, or clusters resembling enterococci or staphylococci. They are rare causative agents of infective endocarditis. Repetitive urinary tract infections based upon underlying genitourinary tract abnormalities could involve these bacteria. Due to their similarity to other Gram-positive cocci misinterpretation may occur along the line of microbiologic differentiation, which could potentially lead to a fatal outcome. We herein report on the clinical course of a 68 year-old male patient who in the setting of an embolic stroke was initially diagnosed with a culture-negative acute infective endocarditis of the aortic valve.