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Abstract: FR-PO610

A Case of IgA-Dominant Infection-Related Glomerulonephritis Caused by Streptococcus mutans Mimicking ANCA-Associated Vasculitis

Session Information

Category: Glomerular Diseases

  • 1302 Glomerular Diseases: Immunology and Inflammation


  • Stark, Ana Isabel, Ochsner Medical Center, New Orleans, Louisiana, United States
  • Kanduri, Swetha Rani, Ochsner Medical Center, New Orleans, Louisiana, United States
  • Medina, Paula A., Ochsner Medical Center, New Orleans, Louisiana, United States
  • Lukitsch, Ivo, Ochsner Medical Center, New Orleans, Louisiana, United States
  • Velez, Juan Carlos Q., Ochsner Medical Center, New Orleans, Louisiana, United States

Group or Team Name

  • Ochsner Nephrology

Infection-related glomerulonephritis (IRGN) can manifest features similar to anti-neutrophilic cytoplasmic antibody (ANCA) associated vasculitis (AAV) in 10-30% of cases, posing a diagnostic challenge. IgA-dominant IRGN is typically observed in the setting of staphylococcal infections. Herein, we report an unusual case of IgA-dominant IRGN with ANCA positivity mimicking AAV in the setting of Streptococcus mutans endocarditis.

Case Description

A 73-year-old woman presented to clinic with a 6-month history of fatigue and a skin rash. Medical history was pertinent for chronic heart failure with preserved ejection fraction and mitral regurgitation. Laboratory data revealed elevated serum creatinine of 1.2 mg/dL (baseline 0.8 mg/dL), positive anti-proteinase-3 (PR3) antibodies (4.2 U) and low hemoglobin (8.4 g/dL). Patient was subsequently admitted to the hospital for further work up. Upon arrival, physical examination revealed a purpuric rash in lower extremities. Additional laboratory data showed positive antinuclear antibody (ANA) (1:640), low haptoglobin (<10), low C3 (30 mg/dL), low C4 (< 3 mg/dL), negative rheumatoid factor and cryoglobulins. Urinalysis revealed hematuria and leukocyturia. AAV was suspected and infectious workup was ordered in an attempt to clear her to initiate immunosuppression. Blood cultures were positive for Streptococcus mutans and transthoracic echocardiography demonstrated multiple vegetations along the anterior mitral leaflet suggesting infective endocarditis. Kidney biopsy was performed and a suboptimal specimen revealed mesangial and subendothelial IgA-dominant immune complex deposits, confirming a case of IgA-dominant IRGN. Following antibiotic initiation, kidney function recovered to a serum creatinine of 1 mg/dL and patient was discharged home. However, shortly after discharge, the patient was readmitted with bifrontal septic emboli, complicated by subarachnoid hemorrhage, and the patient expired.


IRGN presenting with features of AAV is diagnostically challenging and warrants careful clinical evaluation and kidney biopsy interpretation. Streptococcus mutans should be considered as a causative organism for IgA-dominant IRGN along with the more commonly reported Staphylococcus sp.