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Abstract: FR-PO630

Bartonella Endocarditis With Crescentic Glomerulonephritis Mimicking Lupus Nephritis

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation

Authors

  • Sohail, Mohammad Ahsan, Cleveland Clinic, Cleveland, Ohio, United States
  • Tomaszewski, Kristen, Cleveland Clinic, Cleveland, Ohio, United States
  • Calle, Juan C., Cleveland Clinic, Cleveland, Ohio, United States
Introduction

Distinguishing an infectious from an autoimmune cause of glomerulonephritis (GN) is critical in diagnostic challenges such as culture negative infective endocarditis (IE) to avoid exposing patients to inadvertent immunosuppression (IS). Although Bartonella IE appears to be frequently associated with ANCA/PR3 positivity, our case illustrates that Bartonella IE can also cause crescentic GN with positive anti-dsDNA and antiphospholipid (aPL) antibodies, mimicking lupus nephritis.

Case Description

A 74-year-old man presented with fevers, night sweats, weight loss, dyspnea and left upper quadrant abdominal pain. Initial evaluation revealed pancytopenia, acute kidney injury with creatinine of 2.1 mg/dl from baseline 0.8 mg/dl, severe aortic stenosis (AS) on echocardiography and a splenic infarct on abdominal imaging. Urine protein/creatinine ratio was 1.0 and sediment showed normomorphic RBCs. Blood cultures were negative. Serologic testing showed positive ANA/anti-dsDNA/MPO-ANCA, low C3/normal C4 and triple positive aPL profile. Bone marrow biopsy was unrevealing. The patient was initiated on steroids and hydroxychloroquine for possible diagnosis of systemic lupus erythematosus (SLE), and underwent a transcatheter aortic valve replacement (TAVR) for severe AS. Subsequent kidney biopsy revealed crescentic GN with IgM and C3 codominant deposits. The patient's history of AS requiring TAVR raised the possibility of a subacute culture-negative IE as a potential cause for GN. Bartonella was detected by blood PCR testing with positive IgG for Bartonella henselae. Subsequent histopathology of the explanted prosthetic aortic valve under Warthin-Starry stain revealed bacillary organisms in fibrinous vegetations. Anti-dsDNA and aPL antibodies turned seronegative after treatment with ceftriaxone and doxycycline.

Discussion

Anti-dsDNA and aPL antibodies are not typical of Bartonella IE-associated GN. However, the patient’s lack of response to IS, IgM dominant pattern on kidney biopsy, positive Bartonella PCR/serology, and resolution of anti-dsDNA and aPL antibodies following antibiotic therapy, supported Bartonella IE over SLE as the cause of the GN. Although determining the etiology of GN in culture negative IE can be challenging with positive autoimmune serologies, reaching a prompt accurate diagnosis is crucial to prevent inadvertent IS and valve replacement procedures.