Native Valve Emphysematous Enterococcal Endocarditis: Expanding the Differential Diagnosis

Introduction: Emphysematous endocarditis is caused by the gas-forming organisms Citrobacter koseri, Escherichia coli, Clostridium species, and Finegoldia magna. We report the first case of emphysematous endocarditis caused by Enterococcus faecalis. Case report: An 82-year-old man presented with fever and rapidly progressive shortness of breath. He was found to be in atrial fibrillation with rapid ventricular rates. Two-dimensional transthoracic echocardiography demonstrated severe mitral regurgitation. Subsequent two- and three-dimensional transesophageal echocardiogram revealed a large, highly mobile vegetation on the atrial surface of the anterior mitral leaflet with aneurysmal destruction of the lateral scallop requiring mitral valve replacement. Sequencing of the vegetation revealed Enterococcus faecalis, an anaerobic gram-positive coccus that, in rare cases, produces gas using a heme-dependent catalase. Histopathological analysis of the infected valve suggested interstitial gas accumulation, leading to the diagnosis of emphysematous endocarditis. Conclusions: E. faecalis-associated emphysematous endocarditis should be included in the differential diagnosis of valvular vegetation in patients with a rapidly progressing clinical course. When possible, histopathological analysis should be used alongside other imaging techniques to confirm the diagnosis of emphysematous endocarditis. This case also highlights the importance of collecting blood cultures prior to initiating antibiotic treatment.