LEGIONNAIRES' DISEASE: A FATAL FORM OF COMMUNITY-ACQUIRED PNEUMONIA

Abstract

TOPIC: Chest Infections TYPE: Fellow Case Reports INTRODUCTION: Legionella pneumophila is gram-negative bacilli known to cause community-acquired pneumonia (CAP), also termed Legionnaires' disease. While pneumonia is the most common manifestation, extrapulmonary infections include renal injury and rhabdomyolysis. Age, immunosuppression and multi-system infection increase mortality, even with early initiation of therapy. CASE PRESENTATION: A 30-year-old male with history of bipolar disease, alcohol and tobacco abuse presented with diarrhea, fever and confusion for three days. He was found to be febrile, tachycardic, encephalopathic and hypoxic requiring high-flow nasal cannula. Initial evaluation revealed leukocytosis, acute liver injury, acute renal injury, respiratory alkalosis, lactic acidosis, and elevated troponin and creatine kinase levels. Chest x-ray (CXR) showed a dense left upper lobe consolidation. Sepsis was worked up and he was given intravenous fluids and antibiotics (Vancomycin, Cefepime, Metronidazole, Azithromycin). Over several hours, he became oliguric, tachypnic and hypotensive requiring vasopressors, continuous renal replacement therapy (CRRT) and mechanical ventilation. Urinary legionella antigen returned positive so Levofloxacin was added. Despite antibiotics and CRRT, his shock worsened and he ultimately had pulseless electrical activity arrest with demise. DISCUSSION: The presence of acute renal injury in Legionnaires' disease increases mortality up to 51% so early diagnosis is crucial to guide management. The urinary antigen test for L. pneumophila only identifies serogroup 1, which is the most common type. When prevalence is high, specificity of this test is >99%. Severe cases of CAP should be tested for Legionella as half of patients with Legionnaires' disease will require intensive care. Rhabdomyolysis occurs due to direct toxin invasion and renal injury occurs subsequently or due to sepsis. Levofloxacin or Azithromycin are the antibiotics of choice as they are bactericidal and reach high intracellular concentrations. There are twenty-two known cases of Legionnaires' disease with rhabdomyolysis and acute renal injury. Nearly all patients with this triad survived and of those who did, all received antibiotics and about half required hemodialysis (HD). To our knowledge, there is only one other case where the outcome was death despite several days of HD. In comparison, presentation to death occurred in less than twenty-four hours in our case. Cause of death was refractory hyperkalemia due to rhabdomyolysis-induced renal injury despite CRRT. CONCLUSIONS: Even with timely diagnosis and treatment of Legionnaires' disease, renal involvement portends a high mortality rate. At the earliest evidence of renal injury in Legionnaires' disease complicated by rhabdomyolysis, immediate placement of central venous catheters and early initiation of CRRT is mandatory and may be life saving. REFERENCE #1: Soni AJ, Peter A. Established association of legionella with rhabdomyolysis and renal failure: A review of the literature. Respir Med Case Rep. 2019 Oct 28;28:100962. REFERENCE #2: Mercante, J. W., & Winchell, J. M. (2015). Current and emerging Legionella diagnostics for laboratory and outbreak investigations. Clinical microbiology reviews, 28(1), 95–133. REFERENCE #3: Straus W.L., Plouffe J.F., File T.M. Risk factors for domestic acquisition of Legionnaires' disease. Ohio Legionnaires Disease group. Arch. Intern. Med. 1996;156(15):1685–1692. DISCLOSURES: No relevant relationships by Allen Roberts, source=Web Response No relevant relationships by Jigna Solanki, source=Web Response