Glomerular nephropathy associated with chronic Q fever

Of three patients with Coxiella burnetii endocarditis, two developed focal segmental proliferative glomerulonephritis (GN), and the third developed diffuse intracapillary proliferative glomerulonephritis. In one case, a good therapeutic response was followed by partial remission of the renal alterations, but 10 months later there were clinical and histological signs of active glomerular nephropathy, suggesting that the antigenic stimulus persisted. In another case, poor evolution of the infection was accompanied by clinically and histologically aggressive glomerular nephropathy, and advanced renal failure. The third patient, who had diffuse proliferative glomerulonephritis, underwent renal biopsy earlier than the other two cases, and the behavior of the nephropathy has not been aggressive to date. Immunohistopathologic study revealed a diffuse granular deposit of IgM and C3 in all three cases; the first two also presented a discrete linear IgG deposit in the capillary loops. Attempts to identify C burnetii antigen at the glomerular level by immunohistologic techniques failed in two patients. The literature on the association of chronic Q fever with glomerulonephritis is briefly reviewed.