Bacterial endocarditis on a mitral prosthesis with negative blood cultures. Case evolving over a 3 year period in the absence of fever

: A 38 year-old man, operated upon two years previously for combined mitral and tricuspid valve disease of rheumatic origin, presented with signs of a severe biological inflammatory syndrome, and a mild proliferative glomerulonephritis (normal complement with exclusively mesangial deposits of IgM, Clq, and C3 on immunofluorescence), which developed slowly over a period of 3 years in the absence of any fever. Blood cultures were always negative, and prolonged antibiotic therapy on two occasions had no effect on the clinical or biological picture. Mitral prosthesis replacement was necessary 6 months after the onset of the affection, a second leakage 16 months later leading to rapidly fatal heart failure. Pathological examination confirmed the presence of an endocarditis at the zone of insertion of the prosthesis. The slow progression of the disorder in this case, and the absence of fever, emphasize diagnostic difficulties of certain cases of endocarditis, due to low virulence germs, that progress under cover of a generalized disease of renal expression. The value of renal biopsy, which provided almost specific indications in the present case, is also stressed.