Endocarditis caused by Aerococcus urinae: a case report and review of literature

Background: Infective endocarditis is an infectious disease associated with high morbidity and mortality; incidence has been increasing in recent decades. Most common causes of infective endocarditis are Staphylococcus aureus, Streptococci, and Enterococci. Bacteria of the genus Aerococcus are not frequent etiological agents of endocarditis; Aerococcus urinae is a gram-positive bacterium that usually causes common urinary tract infections but can sometimes cause invasive infections such as infective endocarditis. In the past, incidence of Aerococcus urinae infections has likely been underestimated because of its morphological features similar to Staphylococci and Streptococci. Case presentation: We describe the case of a 74-year-old Italian woman with mitral valve endocarditis who presented to the emergency department with focal neurological symptoms associated with cerebral septic embolization; despite the development of severe mitral insufficiency, the size of the vegetation, and the presence of septic embolization, the patient could not be treated with surgical valve replacement in the short term owing to the hemorrhagic evolution of the cerebral lesions, which contraindicated extracorporeal circulation. Antibiotic treatment with ampicillin and levofloxacin was administered for 8 weeks, and after that, the patient was transferred to a rehabilitation unit. Literature review and conclusion: We analyzed cases of infective endocarditis due to Aerococcus urinae described so far in the literature. A total of 68 cases were included in the analysis. Patients were more frequently male (71%); urological risk factors such as benign prostatic hypertrophy, recurrent urinary tract infections, and indwelling catheter were highly represented in the case series. Almost a third of the patients developed septic embolization, and the most common site of embolization was the brain. Mortality rate was about 26.5%. According to international guidelines, in addition to antibiotic therapy, surgical valve replacement should be considered in selected patients since it improves prognosis.