CONGRESS ABSTRACT

An 88-year-old woman with a history of atrial fibrillation and amoxicillin allergy presented progressive dyspnea. She had been treated in the previous three months for pneumonia and bronchitis. Physical examination revealed basal crackles and a 4/6 systolic murmur. Echocardiography identified mobile vegetations in the mitral and aortic valves, severe mitral regurgitation and leaflet perforation of the mitral valve. Laboratory findings included elevated levels of NT-proBNP and fibrinogen. Blood cultures were negative, but valve tissue culture identified Micrococcus luteus, which plausible entered in the bloodstream through a skin or mucosal injury. Empiric antibiotic therapy with ceftriaxone and vancomycin was started. The patient underwent a successful mitral valve replacement with a bioprosthesis and aortic valve shave through endoscopic right minithoracotomy. The postoperative recovery was uneventful, and the patient completed a 6-week antibiotic course. Follow-up echocardiography showed stable prosthesis function and significant symptomatic improvement. This case highlights the evolving microbiology of infective endocarditis associated with gram-positive catalase-positive cocci, typically considered a skin contaminant. Clinicians should recognize Micrococcus luteus as a potential pathogen in susceptible patients and ensure a timely diagnosis and intervention to optimize results.