Abstract: FR-PO0774
When Infection Wears the Mask of Vasculitis: Streptococcus mutans Endocarditis Mimicking ANCA-Associated Vasculitis
Session Information
- Glomerular Diseases: ANCA Vasculitis, Anti-GBM Disease, and Crescentic GN
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Azam, Muhammad Jibran, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Johnson, Jeshanah, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Fadel, Remy, Vanderbilt University Medical Center, Nashville, Tennessee, United States
Introduction
Antineutrophil cytoplasmic antibodies are detected in 18-43% cases of infective endocarditis (IE), making distinction from ANCA- associated vasculitis (AAV) clinically crucial, as inappropriate immunosuppressive (IS) therapy can have devastating consequences. Chronic antigenic stimulation by bacterial products (particularly from staphylococcal and streptococcal species) may be the trigger for autoantibody production including ANCA. We report a case of 67-year-old man whose initial presentation strongly suggested AAV; however, further evaluation revealed a vasculitic process secondary to underlying IE.
Case Description
We describe a case of 67-year-old male with longstanding history of seasonal sinus congestion who began experiencing progressively worsening sinus symptoms in the fall of 2025 that did not respond to multiple courses of antibiotics. Over the same period, he developed additional systemic symptoms, including microscopic hematuria, a skin rash, unintentional weight loss, and acute kidney injury. Outpatient evaluation a positive c- ANCA, raising concern for AAV, and high dose corticosteroid were initiated. Worsening of his AKI led to admission to hospital , he received pulse dose intravenous steroids and kidney biopsy was performed. Pathology revealed focal necrotizing crescentic glomerulonephritis (GN) consistent with pauci-immune disease, along with atypical features including faint full- house immunofluorescence staining, extensive red blood cell, and acute interstitial nephritis with eosinophils and polymorphonuclear cells. Given concern for possible valvular abnormality on echocardiography, further evaluation was pursued and ultimately demonstrated IE driven by Streptococcus Mutans. He was treated with intravenous antibiotics and gradual tapering of oral corticosteroids. Following treatment of his IE, his renal function steadily improved and ultimately normalized.
Discussion
This case highlights that atypical pauci-immune GN with IE-associated GN overlap. Identifying and treating the underlying infection in our case was critical leading to renal recovery and avoidance of unnecessary prolonged immunosuppression. ANCA in IE may be both an epiphenomenon of chronic infection and, in some cases, potentially pathogenic. Patient will need to follow up OP with rheumatology to make sure he doesn't later develop ANCA vasculitis.