Glomerulonephritis caused by bartonella spp. infective endocarditis: The difficulty and importance of differentiation from anti-neutrophil cytoplasmic antibody-related rapidly progressive glomerulonephritis

A 65-year-old man with valvular disorder presented to his physician because of widespread purpura in both lower extremities. Blood tests showed elevated serum creatinine levels and proteinase 3-anti-neutrophil cytoplasmic antibody (ANCA) with hematuria, suggesting ANCA-related rapidly progressive glomerulonephritis (RPGN). Although multiple blood cultures were negative, transthoracic echocardiography revealed warts in the valves, and a renal biopsy also showed findings of glomerular infiltration by mononuclear leukocytes and C3 deposition in the glomeruli, suggesting infection-related glomerulonephritis. Later, Bartonella antibody turned positive. Antimicrobial treatment improved the purpura and renal function without any recurrence. ANCA-positive RPGN requires the exclusion of infective endocarditis, especially that induced by Bartonella spp.