Kidney Week

Abstract: FR-PO0788

Myeloperoxidase (MPO)-ANCA Glomerulonephritis Secondary to Mycobacterium abscessus: A Rare Case of Infection-Induced Vasculitis Response to Antibiotics and Corticosteroids Alone

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

• El Hajjar, Rayan, Banner - University Medical Center Tucson, Tucson, Arizona, United States

Rayan El Hajjar, MD

• Hada, Muzammeel Dosanbhai, Banner - University Medical Center Tucson, Tucson, Arizona, United States

Muzammeel Dosanbhai Hada, MD, FASN

• Weerasinghe, Sanjeeva Neranjan, Banner - University Medical Center Tucson, Tucson, Arizona, United States

Sanjeeva Neranjan Weerasinghe, MD

• Thajudeen, Bijin, Banner - University Medical Center Tucson, Tucson, Arizona, United States

Bijin Thajudeen, MD, FASN

• Mansour, Iyad S. M., Banner - University Medical Center Tucson, Tucson, Arizona, United States

Iyad S. M. Mansour, MD, MBChB

Introduction

This case illustrates infection-induced MPO-ANCA glomerulonephritis triggered by Mycobacterium abscessus, with clinical improvement following antimicrobial therapy and corticosteroids without additional immunosuppression, highlighting a reversible infection-driven process rather than primary ANCA vasculitis.

Case Description

A 57-year-old female with chronic cough managed by an outside pulmonologist presented with acute kidney injury. Workup revealed rapidly progressive glomerulonephritis with MPO-ANCA positivity. Kidney biopsy showed necrotizing and crescentic glomerulonephritis of pauci-immune type with approximately 70% globally sclerosed glomeruli. A chest CT scan revealed localized cystic densities and ground-glass opacities. Bronchoscopy with bronchoalveolar lavage subsequently yielded Mycobacterium abscessus complex, and AFB culture sensitivity testing demonstrated multidrug resistance.
The patient received pulse-dose intravenous methylprednisolone, and antimicrobial therapy was initiated. No additional immunosuppressive agents were administered.
With corticosteroids and antimicrobial therapy alone, the patient demonstrated improvement in renal function and improvement in hematuria and proteinuria. MPO ANCA titre remained positive. This clinical response supports infection-induced ANCA rather than primary AAV requiring aggressive immunosuppression.

Discussion

Distinguishing primary ANCA-associated vasculitis from infection-induced disease is critical, as aggressive immunosuppression in the setting of active infection may lead to catastrophic outcomes.
Proposed mechanisms include infection-driven immune activation with loss of immune tolerance and subsequent MPO-ANCA production mediated through molecular mimicry between bacterial antigens and self-antigens. In this context, infections may act as pathogenic triggers that convert natural autoantibodies into pathogenic ANCAs.
Although the kidney biopsy demonstrated 70% globally sclerosed glomeruli, the active necrotizing and crescentic lesions resolved with treatment. This case therefore reinforces the importance of targeted antimicrobial therapy combined with corticosteroids, without additional immunosuppression.