Necrotizing glomerulonephritis caused by Bartonella henselae endocarditis.

Glomerulonephritis secondary to endocarditis is uncommon and usually associated with valvular infection by blood culture-positive bacteria. We report 3 cases of necrotizing glomerulonephritis associated with culture-negative endocarditis caused by Bartonella henselae. Two of the patients presented with renal abnormalities and were investigated for endocarditis after results of renal biopsy. All 3 patients had an immune complex-mediated necrotizing and crescentic glomerulonephritis with mesangial and capillary wall deposition of immunoglobulin M (IgM), IgG, and C3. Electron microscopy showed immune-type electron-dense deposits in the mesangium and segmental subendothelial (2 cases) or subepithelial (1 case) deposits. Patients were treated with antibiotics, including azithromycin or doxycycline and ceftriaxone or tobramycin. In addition, 2 patients were administered steroids and 2 patients underwent valve replacement surgery. The 2 patients who underwent cardiac surgery were discharged from the hospital with stable renal function. The third patient died 4 months after hospital admission of renal failure. In conclusion, glomerulonephritis caused by B henselae endocarditis is an immune complex-mediated disease characterized by segmental necrotizing and crescentic glomerular lesions that can respond to aggressive medical and surgical therapy.