A RARE CASE OF PRIMARY FOCAL SEGMENTAL GLOMERULOSCLREOSIS TRIGGERED BY LEGIONELLA PNEUMONIA

Focal segmental glomerulosclerosis (FSGS) is a subset of glomerular disease resulting from podocyte injury and commonly presents as nephrotic syndrome and has the potential to advance into End Stage Renal Disease (ESRD). FSGS can be associated with infections like Human Immunodeficiency Virus (HIV), Hepatitis B (HBV), Hepatitis C (HCV), Parvovirus B19, Cytomegalovirus (CMV), SARS-CoV-2 and dengue virus. We report the first case of an association between legionella and primary FSGS.

A 40 year old case presented with history of fever for 1 week along with cough and respiratory distress. On evaluation he was found to have left middle and lower multiple infiltrates with ground glass opacities. He underwent bronchoscopy and lavage with multiplex PCR showing positive for Legionella. Post admission day 1 he started developing progressive anasarca. On evaluation he was found to have hypoalbuminemia of 1.9 gm/dl (previously normal albumin) and nephrotic range proteinuria with new onset Acute Kidney Injury with creatinine of 2.3 mg/dl. He was started on Moxifloxacin for legionella and albumin infusion. Subsequently he underwent an uncomplicated renal biopsy. His creatinine improved and renal biopsy showed evidence of Focal Segmental Glomerulosclerosis . He was started on oral Prednisolone 1mg/kg/day and was discharged with oral fluoroquinolones. He was followed up over the next 2 months in which he attained remission and his Prednisolone course was tapered over the next 6 months.

The most widely reported manifestation of Legionella infection is pneumonia, which is also known as Legionnaires’ disease. Legionnaires’ disease is typically spread through inhalation of aerosolized water droplets containing Legonella bacteria. Our patient gave history of exposure to air conditioner for prolonged duration. Acute Kidney Injury(AKI) is the most common renal manifestation in Legionella disease and is probably due to the cytotoxic effects of bacteria that directly invade renal tubular epithelial cells. Indirect causes for acute kidney injury include dehydration and nephrotoxic medication. Proteinuria if present is mainly transient and resolves spontaneously on subsequent follow up. However, no case of nephrotic syndrome has been reported. Possible mechanism is deposition of immune complexes in the glomerulus, which leads to inflammation and damage direct infection of podocytes, protein leading to podocyte injury, foot process effacement, and subsequent scarring. In this case the cause of AKI was most likely due to nephrosarca, because renal dysfunction improved with albumin infusion. In view of the nephrotic syndrome presentation and segmental sclerosis on renal biopsy we labelled it as a primary FSGS subset. Primary FSGS is rare secondary to infection but it can be triggered due to secondary immune system activation. Most renal biopsies performed in patients with confirmed diagnosis of Legionnaires’ disease and renal involvement include findings of tubulointerstitial nephritis and/or ATN with a favorable response to corticosteroid treatment and antibiotics. Here we got a surprising finding of FSGS with diffuse foot process effacement as the etiology of nephrotic syndrome and responded dramatically to steroids attaining remission.

This is the first case of FSGS related nephrotic syndrome secondary to a non viral Legionalla infection. We should be aware of such scenarios since rapid diagnosis and timely initiation of steroids can help in attaining remission and prevent progression to Chronic Kidney Disease.