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Around 50 % of cases of infection-associated glomerulonephritis in developed countries are caused by Streptococci and Staphylococci. The remainder is related to a wide variety of other bacteria, viruses, parasites, and fungi. A kidney biopsy is mandatory for diagnosis and typical changes of postinfectious glomerulonephritis are C3 deposits ± immunoglobulin deposits, but other less common diagnoses that need to be entertained in the background of infection include C3 glomerulopathy and ANCA-mediated pauci-immune glomerulonephritis. The mainstay of therapy in these patients is clearance of infection. There may be a role for immunosuppressive therapy in severe crescentic glomerulonephritis or if pauci-immune glomerulonephritis is a consideration.
A 41-year-old, previously healthy, with no known past medical history, presented to the ED with a 3-day history of fever, vomiting, and loose stools. Her temperature reached 40 degrees Celsius. She had dry mucous membranes and cold extremities, and She was in hypotension in the emergency room but responded to initial fluid resuscitation. Her initial labs showed Creatinine of 844 micromol/L and urea of 22 mmol/L. her serum bicarbonate was 16 mmol/L, sodium 130 meq/L, potassium 3 meq/L. Procalcitonin was 6 ng/mL. WBCs 9.4x 10^9/L. C-reactive protein 105 ng/L and Hemoglobin 140 g/L. complements C3 and C4 were normal along with negative antinuclear antibodies and Ds DNA antibodies.
She was started on maintenance intravenous hydration and ceftriaxone 2 grams, despite all conservative measures her creatinine was increasing 893 micromol/L. The nephrology team decided on a kidney biopsy. Renal ultrasound showed both kidneys are enlarged hypoechoic of normal shape and position and preserved corticospinal differentiation. No stones, focal parenchymal lesions, calcification, or hydronephrosis. Smooth cortical outline and no perinephric collection with normal Doppler ultrasound. The kidney biopsy showed patchy mixed interstitial inflammatory cell infiltration consisting of Lymphocytes mainly, with eosinophils, few neutrophil polymorphs, and mast cells, together with prominent acute tubular necrosis consistent with acute tubulointerstitial nephritis mesangial proliferation and granular C3 only staining (+2) by IF stain consistent with C3 glomerulonephritis with mesangioproliferative pattern of glomerular injury. Her blood culture showed Salmonella species, Group C+D growth, stool culture was negative.
her creatinine reached a peak of 943 micromol/L with urea of 25 mmol/L and she was anuric so a hemodialysis session was decided. She received only one session and started on pulse steroids immedietly after the biopsy. Creatinine started to improve , the last creatinine immedietly prior to discharge was 183 micromol/L. the patient inflamatory markers dropped significantly with antibiotics treatment.
The patient's renal function improved with treatment of the infectious cause, she required one hemodialysis session after which her urine output improved to more than 2L per day and creatinine improved to 183 micromol/L. Treatment of the infectious cause is the mainstay therapy for C3 glomerulopathy in this case.