Abstract: TH-PO189

Bartonella Endocarditis Mimicking ANCA-Associated Glomerulonephritis (GN)

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports

Authors

  • Vercellone, Joseph, Oakland University/William Beaumont School of Medicine, Royal Oak, Michigan, United States
  • Cohen, Lisa J., Oakland University/William Beaumont School of Medicine, Royal Oak, Michigan, United States
  • Mansuri, Saima, Oakland University/William Beaumont School of Medicine, Royal Oak, Michigan, United States
  • Zhang, Ping L., Oakland University/William Beaumont School of Medicine, Royal Oak, Michigan, United States
  • Kellerman, Paul S., Oakland University/William Beaumont School of Medicine, Royal Oak, Michigan, United States
Background

Bartonella henselae is a fastidious organism causing cat scratch disease, commonly associated with fever and lymphadenopathy. Rarely, B. henselae results in culture-negative endocarditis (IE). Herein, we describe a case of B. henselae IE mimicking ANCA-associated GN.

Methods

A 47-year-old male presented with 2 weeks of flank pain and four days of cola-colored urine. Exam revealed a soft murmur over the left-sternal border and severe CVA tenderness, with no fever. Labs showed a Hgb of 7.7 mg/dL, a creatinine of 2.36 mg/dL (up from 0.89 mg/dL), and UA showed 3+ blood, 1+ protein, 51-100 RBC/HPF, 0-5 WBC/HPF, and RBC casts. Kidneys were normal on ultrasound, but MRI noted wedge-shaped splenic infarcts. Pending serologic studies and biopsy, the patient was initially pulsed with steroids with no further immunosuppression. Serologies revealed normal C3, C4, ASO, ANA, anticardiolipins, IgA, and hepatitis panel. ANCA and anti-MPO were negative, but anti-PR3, CRP and ESR were markedly elevated. On biopsy, light microscopy showed focal proliferative injury with two non-necrotic crescents. Immunoflourescence was positive for IgM, IgA, C3, and C1q. Electron microscopy showed subtle mesangial and subendothelial deposits without “humps”. With possible immune complexes on kidney biopsy and a murmur, TEE was performed showing a bicuspid aortic valve with vegetation. A diagnosis of culture-negative endocarditis was made, doxycycline and rifampin were started, and valve replacement performed, with pathology identifying B. henselae. On antibiotics, the patient’s symptoms resolved and creatinine decreased to 1.4 mg/dL with normalization of ESR and CRP over two months.

Conclusion

Culture-negativity comprises 3-48% of all endocarditis cases. This case highlights how Bartonella IE can present with crescentic GN and falsely elevated anti-PR3 antibodies mimicking ANCA-associated GN. Literature review revealed approximately 50 cases of Bartonella-induced IE with GN with ANCA and PR-3 positivity. Unique to our case was a negative ANCA with very high anti-PR3 antibody titer. Because of culture negative IE and false vasculitis titers, Bartonella can mimic ANCA-associated GN, thus kidney biopsy showing immune complex deposition is critical to diagnosis and appropriate therapy.