Blood Culture-Negative Legionella TAVR Endocarditis

Legionella endocarditis is exceedingly rare and diagnostically challenging. We present the first confirmed case of blood culture-negative Legionella cardiaca prosthetic valve endocarditis (PVE).

A 77-year-old man with prior transcatheter aortic valve replacement presented with 8 months of daily fevers, malaise, and unintentional weight loss. Serial blood cultures were negative. Multimodality imaging suggested transcatheter aortic valve replacement-PVE, with significant valvular obstruction. Plasma microbial cell-free DNA sequencing detected Legionella species, prompting targeted therapy. The prosthetic valve was explanted, and histopathology revealed numerous bacilli. Broad-range 16S rRNA sequencing confirmed Lcardiaca.

This case highlights the diagnostic complexity of culture-negative Legionella PVE and the value of multimodality imaging and molecular techniques for accurate diagnosis and management.

Multimodality imaging plays an integral role in the diagnosis of infective endocarditis. Molecular diagnostics should be considered early in blood culture-negative endocarditis, particularly when conventional microbiologic testing is unrevealing.