Fatal Aerococcus urinae Aortic Valve Endocarditis with Severe Regurgitation

Objective: Rare diseaseBackground: Aerococcus species are a rare cause of endocarditis. Micro-organism identification and antibiotic choice can pose significant management challenges to clinicians who care for patients with this infection. Aerococcus is a gram-positive micro-organism which is commonly misidentified because it shares many similarities with strep-tococcus and enterococcus species. Aerococcus urinae is usually found to cause urinary tract infections and oc-curs more frequently in patients with structural urinary tract abnormalities associated with urethral and ure-teral obstruction such as kidney stones, phimosis, and prostate hyperplasia. However, it is reported to rarely cause endocarditis.Case Report: A 48-year-old man with a history of cocaine abuse and right hip replacement presented to our emergency department with acute encephalopathy. Through a complicated hospital course, he was found to be septic and the bacteria were initially misidentified as an alpha-hemolytic strep before being correctly identified as Aerococcus urinae. He was found to have multiple cerebral, likely septic, embolic infarcts and aortic valve en-docarditis. Identification of the micro-organism on blood cultures was challenging, as were decisions about an-tibiotic choice. He died despite efforts of a multidisciplinary care team.Conclusions: Our case highlights a unique case of Aerococcus endocarditis and shows the difficulty in initially identifying the bacteria. To our knowledge this is the first case reported in the setting of substance abuse. It also high-lights the lack of appropriate guideline-directed therapy with regards to antibiotic choices in this group of pa-tients, emphasizing the importance of further research in this regard.