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Published on: June 18, 2020
A case of acute poststreptococcal glomerulonephritis complicated by interstitial nephritis related to streptococcal
Nobuhiro Kanazawa1, Masayuki Iyoda1,2, Junichi Hayashi1
1Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
Abstract:
This paper presents the case of a patient who developed acute kidney injury and nephrotic syndrome following streptococcal cutaneous infection. He presented with microhematuria, severe proteinuria and systemic edema 5 days after infection. Blood examination showed elevated creatinine level, hypocomplementemia, and elevated anti-streptolysin O level. Renal biopsy revealed endocapillary proliferative glomerulonephritis with tubulointerstitial nephritis (TIN). Immunofluorescence revealed C3-dominant glomerular staining, while electron microscopy showed hump-shaped subepithelial deposits. The patient was therefore diagnosed with poststreptococcal glomerulonephritis. The unique histological feature was C3 deposition in the tubular basement membrane (TBM), in which we detected streptococcal pyrogenic exotoxin B (SpeB), a nephritogenic antigen produced by streptococci. No nephritis-associated plasmin receptor or plasmin activity was evident in the TBM. These nephritogenic antigens and upregulation of plasmin activity were observed in glomeruli. This case suggests that TIN after poststreptococcal infection might be partially attributable to SpeB toxicity.
Insights
This case study reveals that streptococcal pyrogenic exotoxin B (SpeB) may contribute to acute kidney injury and nephrotic syndrome after skin infections. SpeB toxicity might play a role in tubulointerstitial nephritis following post-streptococcal conditions.
Area of Science:
- Nephrology
- Infectious Diseases
- Pathology
Background:
- Post-streptococcal glomerulonephritis (PSGN) is a common complication of streptococcal infections.
- Acute kidney injury (AKI) and nephrotic syndrome can occur following streptococcal cutaneous infections.
- The pathogenesis of tubulointerstitial nephritis (TIN) in PSGN is not fully understood.
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