Native Mitral Valve Endocarditis Caused by Neisseria elongata subsp. nitroreducens in a Patient with Marfan Syndrome: First Case in Italy and Review of the Literature

Abstract

Neisseria elongata (NE) is an aerobic Gram-negative organism that constitutes part of the commensal human normal oropharyngeal flora. Although previously considered not to be pathogenic, it has been recognized as an occasional cause of significant infections in humans. We report here the first case in Italy of infective endocarditis of a native prolapsing mitral valve in a patient with Marfan syndrome, caused by NE subspecies nitroreducens which has been rarely isolated from clinical specimens. The culprit organism has been confirmed by mass spectrometry directly from the positive blood culture, as previously reported. The amplified gene has been deposited in GenBank under accession number KT591873. In spite of the reported aggressive nature of NE, clinical remission was promptly obtained, there being no requirement for surgery.

Figure 1

TTE 4-chamber views showing (a) a vegetation arising from the posterior leaflet of mitral valve. The vegetation was confirmed with TOE (c) that also documented a severe mitral regurgitation (d) and the prosthetic aortic valve (b). la: left atrium, lv: left ventricle, ra: right atrium, rv: right ventricle, and AoP: prosthetic aortic valve.

Figure 2

TOE 4 chambers: the admission of TOE on (a) shows a vegetation on the posterior leaflet of mitral valve. The follow-up TOE (b) confirmed the persisting of the vegetation of reduced dimensions, compared with the previous exam (a), despite clinical remission.