Abstract: SA-PO0879
Bartonella-Associated Crescentic Glomerulonephritis (GN) and AKI: Infection Mimicking Autoimmunity
Session Information
- Glomerular Case Reports: ANCA, IgA, IgG, and More
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Kattubadi, Ayeesha, University of California San Francisco, San Francisco, California, United States
- Sam, Ramin, University of California San Francisco, San Francisco, California, United States
- Urisman, Anatoly, University of California San Francisco, San Francisco, California, United States
- Sarathy, Harini, University of California San Francisco, San Francisco, California, United States
Introduction
Bartonella-associated GN is a rare, often misdiagnosed mimic of autoimmune RPGN. We present a case series of 7 marginally housed patients with AKI and biopsy-proven Bartonella-associated crescentic GN treated at a safety-net hospital in San Francisco between 2019–2024. The University of California San Francisco’s Institutional Review Board approved this study.
Case Description
All patients presented with AKI, microscopic hematuria, new anemia, negative blood cultures, elevated ESR and CRP, hypocomplementemia (low C3 &/or C4) and biopsy-confirmed crescentic glomerulonephritis (6/7 had immune-complex GN, endocapillary and/or mesangial hypercellularity and deposits with IgG+, IgM ±, IgA+, C3+++, C1q++ staining; 1 had pauci-immune focal necrotizing GN). All patients were treated with pulsed-dose steroids prior to testing for Bartonella infection. Median age was 56 years (IQR 46.5-65) and 6/7 were male. Common features were marginalized housing status (shelter or incarcerated) (6/7) and months-long variable prodrome of fatigue, weight loss, rash or fever (6/7). Other risk factors were few, history of intravenous drug use (1/7), body lice (1/7) and cat exposure (2/7). None had diabetes or hypertension. Urinalyses showed hematuria (7/7), pyuria (6/7), and variable proteinuria (sub-nephrotic to nephrotic range). Only 1/7 had hepatitis-C infection; all tested negative for HIV, hepatitis B and RPR. All patients were positive for Bartonella quintana IgG (IgM +ve in 1) and Bartonella henselae IgG (all IgM -ve) with minimum dilution titers of 1:512 (positivity ≥1:256). All tested negative for ANCA antibodies, but 4 patients had PR3+ antigen, and 1 patient had PR3+/MPO+. Transesophageal echocardiography confirmed endocarditis in 3 patients, detected in 1, ruled it out in 2 and was not done in 1 patient. All patients were treated with doxycycline ± rifampin (or ceftriaxone) for a minimum 6-week course. Of the 7 patients, 3 had AKI-requiring dialysis; 2 died within 3 months, and 1 recovered renal function within 1 week; the 4 patients without AKI-D had persistent CKD stages 3-4 at follow up (3-36 months).
Discussion
Early recognition of Bartonella-associated GN, which mimics autoimmune RPGN, and endocarditis evaluation are crucial to initiating appropriate treatment and improving outcomes. Marginalized housing is a major risk factor.