#2864 IgA dominant post-infectious glomerulonephritis secondary to the infected left ankle joint in a non-diabetic patient, a case report
Authors: Habeeb Michael , Ghalli Farid 
Published: May 2024

Abstract

Introduction
Post-infectious glomerulonephritis (PIGN) is an immune complex glomerulonephritis that commonly affects children and young adults following beta haemolytic Streptococcal throat or skin infections. Kidney biopsy is characterised by Segmental or global endocapillary hypercellularity, and crescents may be present. In immunofluorescence, post-infectious glomerulonephritis typically shows IgG and C3 deposition.
A rare type of PIGN is IgA-dominant post-infection glomerulonephritis. It commonly occurs in the setting of active infection. It usually presents in patients &gt; 60 years old with diabetes mellitus, alcohol consumption, and Staphylococcal infections. It can present with RPGN, AKI, and nephrotic syndrome. Hypocomplementemia can be present, and immunofluorescence is characterised by IgA dominance with C3 co-dominance and no IgG. Despite the strong association with Staph aureus, however, it has been reported with other types of infections.
The main line of treatment is antibiotic eradication of the infection. Steroids can be used based on the severity of the lesion and the presence of crescents. Its prognosis is worse than that of the traditional PIGN.
In this case, we report a case of IgA-dominant post-infectious glomerulonephritis secondary to left ankle osteomyelitis with Staph aureus infection.

Case Presentation
A 65-year-old lady had open reduction and internal fixation of a left trimalleolar ankle fracture in June 2023 at a district general hospital. Unfortunately, the post-operative course was complicated by wound infection. The wound swab showed Heavy growth of Staphylococcus aureus. This was followed by Acute Kidney Injury (AKI) stage 3; therefore, she was transferred from her hospital to our renal ward. On admission to the ward, her creatinine was 388 μmol/L(baseline creatinine was 73 μmol/L one month before admission), urine dipstick was positive for blood and protein, and urine protein creatinine ratio was 480 mg/mmol. She had only a medical background of bronchial asthma for which she was only on Inhalers (Beta Agonist) as a regular medication.
CT scan of the left ankle revealed appearances consistent with osteomyelitis of both the lateral and medial malleoli. This finding was discussed with microbiology and orthopaedic teams, and the patient was started on intravenous antibiotics (Vancomycin followed by doxycycline).
A kidney biopsy was done. Mesangial electron-dense deposits were identified. Immunohistochemistry revealed IgA dominant, predominantly mesangial positivity, with associated C3. The picture was consistent with IgA acute glomerulonephritis associated with S. aureus, which is a post-infectious Glomerulonephritis with dominant IgA staining (rather than conventional IgA nephropathy).
With proper intravenous hydration and antibiotics, her inflammatory markers started to improve, and her renal chemistry followed the inflammatory markers, and her last creatinine improved to 146 μmol/L, eGFR 31 ml/min and UPCR was 40 mg/mmol.

Discussion
IgA-dominant post-infectious glomerulonephritis is now a distinct form of PIGN, which usually presents with acute kidney injury, haematuria, and proteinuria and is typically related to Staph aureus infection. In contrast to typical IgA nephropathy, there is no role for steroid or immunosuppression in the treatment of IgA-dominant post-infectious glomerulonephritis, and the treatment is mainly dependent on the treatment of infection.