A case of chronic Campylobacter fetus infection-related glomerulonephritis, mimicking systemic autoimmune diseases.

Herein, we present the first case of chronic Campylobacter fetus infection-related glomerulonephritis (IRGN) in a 69-year-old man with a permanent cardiac pacemaker. The patient had a prior episode of fever and glomerulonephritis of undetermined etiology, and at that time, low-dose steroid therapy resulted in improved urinary findings and kidney function. This time the patient again developed deterioration of kidney function with microhematuria, proteinuria, high serum C-reactive protein levels, and positive titers of anti-double-stranded DNA antibody and proteinase 3 anti-neutrophil cytoplasmic antibody (ANCA). A kidney biopsy revealed endocapillary and mesangial hypercellularity, interstitial infiltration of neutrophils, and positive staining for C3 and IgM in the mesangium and glomerular capillary walls. Notably, histological staining for nephritis-associated plasmin receptor (NAPlr)/plasmin activity was also positive. Similar laboratory and pathological findings in the first and second kidney biopsies and repeated detection of C. fetus in blood cultures led to the diagnosis of IRGN associated with persistent pacemaker-related infection. The nephritis improved following antibiotic therapy targeting C. fetus. C. fetus can cause sustained bacteremia and prolonged infection of indwelling devices, and can be a causative organism for recurrent IRGN. Clinicians must distinguish IRGN from autoimmune diseases such as lupus nephritis and ANCA-associated vasculitis.