Aerococcus Viridans Endocarditis and Cerebral Emboli Without Evidence of Urinary Pathology

Abstract

INTRODUCTION: Aerococci are gram positive cocci typically associated with genitourinary infections. Aerococcus viridans is a pathogen typically seen in urinary tract infections, rarely causing systemic infections including bacteremia and endocarditis. We present a case of A. viridans bacteremia with infective endocarditis and associated septic emboli, without evidence of concomitant urinary tract infection. CASE PRESENTATION:An 84-year-old woman presented to the hospital with altered mental status and left sided visual field changes. Vitals were consistent with sepsis and she was empirically started on Ceftriaxone. Magnetic resonance imaging demonstrated extensive multifocal infarcts in the right occipital lobe and thalamus. Trans-esophageal echocardiogram revealed a two millimeter focal echodensity on the left coronary cusp of the aortic valve, consistent with infective endocarditis. Blood cultures were positive for pan-susceptible Acinetobacter with Aerococcus viridans resistant to beta lactams. A urine sample collected on admission grew only Escherichia coli. The patient was started on a six-week course of intravenous Vancomycin. Repeat blood cultures collected after completion of antibiotic therapy showed resolution of bacteremia. A follow up trans-thoracic echocardiogram did not show any persistent endocarditis.DISCUSSION: Aerococcus species are typically found in the urine, but this patient's urine culture was negative for aeroccus viridans. Of the two bacteria seen on blood culture, Aerococcus is thought to be the more likely pathogen of the endocarditis leading to septic emboli. Endocarditis is more frequently due to Gram positive organisms, and it is less likely that Acinetobacter, a Gram negative rod, would be the underlying pathogen. To further support our explanation, there are morphologic similarities between A. viridans and viridans streptococci, which are known to cause endocarditis. In terms of treatment, Aerococcus species are frequently susceptible to penicillins. In this case, A. viridans was resistant to both penicillins and cephalosporins, requiring therapy with Vancomycin.CONCLUSIONS: In the past, exact identification of organisms like Aerococcus were difficult and the clinical significance of many isolates remained obscure. Aerococcus urinae is the most documented strain with reports of urinary tract infection leading to endocarditis. We report a rare cause of idiopathic A. viridans resistant to penicillin causing infective endocarditis and cerebral emboli without associated genitourinary pathology. Aerococcus endocarditis, though rarely documented, can have severe complications including septic emboli with a significant risk of morbidity and mortality. Regardless of the source, Aerococcus infections with progression to bacteremia should raise suspicion for endocarditis.