Abstract
Background: Infection-related glomerulonephritis (IRGN) has witnessed evolving epidemiological patterns. While pediatric IRGN has been extensively studied, adult IRGN remains less explored. Differentiating between IRGN and similar clinical presentations of glomerulonephritis in adults is crucial for optimal management and predicting prognosis.

Aims and Objectives: The aim of this study was to analyze the clinical, pathological, and outcome patterns in adults diagnosed with IRGN. The study also aimed to identify the significance of kidney biopsy, including electron microscopy, in diagnostic and prognostic evaluation. Furthermore, the research sought to recognize factors influencing poor renal outcomes in adult IRGN.

Materials and Methods: This was a retrospective analysis of 115 adults diagnosed with IRGN. Data related to clinical presentation, preceding infections, laboratory parameters, and histopathological findings were meticulously collated. Renal biopsies were examined with light microscopy, immunofluorescence, and electron microscopy. Outcomes were categorized as complete recovery, persistent urinary abnormalities, persistent renal dysfunction, end-stage renal disease (ESRD), and mortality at 1-year follow-up.

Results: The mean age of the cohort was 46.06 years, with a male predominance. Streptococcus pyogenes and Staphylococcus aureus were the leading causative organisms. Seasonal trends pointed to a peak incidence in July. Notably, 28.7% of the patients had diabetes mellitus. At presentation, 80% had acute kidney injury, with 25% necessitating dialysis. Hypocomplementemia was observed in the majority, with 87% having a reduced C3 level. Electron microscopy revealed a mean glomerular basement membrane thickness of 438 nm ± 178.05, with 55% showing subepithelial humps. The crescent formation was present in 11.3% of biopsies. Treatment modalities included antibiotics (33%), antihypertensive (51.3%), and steroids (18.3%). At the 1-year mark, 51.3% achieved complete recovery, 15.7% had persistent urinary anomalies, and 6.1% progressed to ESRD. Two patients succumbed within the year. Advanced age, diabetes, crescents, interstitial fibrosis, tubular atrophy, underlying diabetic glomerulosclerosis, and subepithelial humps were predictors of poor renal outcomes.

Conclusion: In adults, the epidemiology, complications, and long-term outcomes of IRGN markedly differ from the pediatric population. Due to the similarity in clinical presentations of various glomerulonephritis, kidney biopsy in adult patients suspected of IRGN becomes pivotal for accurate diagnosis and prognostication.

Key words: Infection-related Glomerulonephritis; Kidney Biopsy; Immunoglobulin A Dominant; Diabetic Glomerulosclerosis; Interstitial Fibrosis and Tubular Atrophy; Crescentic Glomerulonephritis