Meningococcal endocarditis with profound acquired hypocomplementaemia.

A patient is described who presented with chronic endocarditis, due to Neisseria meningitidis, affecting a previously normal mitral valve. The illness was associated with glomerulonephritis that caused renal impairment and the nephrotic syndrome. Despite antibiotic treatment and replacement of the mitral valve, serum complement values remained very low, only returning to normal when immune complexes and a type III cryoglobulin disappeared from the circulation three months after resection of the valve vegetation. Such acquired hypocomplementaemia may have contributed to the chronicity of the disease process in this patient.