Neisseria elongata prosthetic valve endocarditis: case report and literature review

Abstract

Introduction: Neisseria elongata, a Gram-variable, rod-shaped organism, was previously thought to be non-pathogenic. However, in recent years it has become increasingly recognized as a rare cause of infective endocarditis. Here, to the best of our knowledge, we describe the first case of bivalvular prosthetic valve endocarditis due to N. elongata. Case Presentation: A 55-year-old Taiwanese man with history of Streptococcus viridans endocarditis status post prosthetic mitral and aortic valve replacements presented with a 2-week history of progressive fatigue and altered mental status. He presented with fever, lethargy and shock. He was intubated and started on vasopressors. A systolic murmur was noted with leukocytosis and acute renal failure. He was started on broad-spectrum antibiotics. An initial trans-oesophageal echocardiogram (TOE) did not reveal vegetation, but showed an elevated aortic valve gradient of 70 mmHg consistent with severe aortic stenosis. A repeat TOE revealed multiple mobile and immobile mitral and aortic valve vegetations with an abscess extending toward the aortic valve. Three sets of positive blood cultures from admission identified N. elongata. Antibiotics were tailored to ceftriaxone. He underwent urgent aortic and mitral valve replacement. He completed a 6-week course of ceftriaxone. At discharge, two-dimensional echo revealed normal heart function with normal prosthetic mitral and aortic valves. Conclusion: N. elongata is an uncommon, but increasingly recognized, cause of infective endocarditis. It causes severe valvular destruction with systemic complications and often requires surgical intervention.