Abiotrophia defectiva endocarditis implicated in antineutrophil cytoplasmic antibody-negative glomerulonephritis

We report a rare case of antineutrophil cytoplasmic antibody (ANCA)-negative pauci-immune necrotising glomerulonephritis (PING) in Abiotrophia defectiva (A. defectiva) endocarditis. A woman in her 50s presented to the hospital with acute kidney injury (AKI), pancytopenia, microscopic haematuria, proteinuria and maculopapular rash. She had A. defectiva sepsis and endocarditis. Serologies were positive for antinuclear antibody and low complement components 3 and 4 but negative for ANCA. A kidney biopsy revealed PING with minimal focal crescents, fibrinoid necrosis and tubulointerstitial fibrosis. She was managed with antibiotics and mitral valve replacement alone. Haemodialysis (HD) was initiated briefly until renal recovery. She remained in complete remission after 2 years. This case illustrates the complex immune response to bacterial endocarditis resulting in ANCA-negative PING. The appropriate use of antibiotics and surgical intervention without immunosuppression in A. defectiva endocarditis led to the resolution of AKI and maculopapular rash.