LEGIONELLA INFECTION IN THE MIDST OF COVID-19 PANDEMIC

Abstract

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: With the COVID-19 pandemic, when 90% of ICU has COVID-19 patients, it's common to overlook other rare causes of acute hypoxic respiratory failure. Our case highlights the importance of maintaining a broad differential for pneumonia and importance of early urine legionella antigen testing. CASE PRESENTATION: 55 year-old male with no significant medical history presented with 8 day history of fever, chills and dry cough. Exam was unremarkable except bilateral rales. Labs were significant for elevated inflammatory markers done as part of a COVID panel with C-reactive protein >190, troponin 0.063, d-dimer >20, ferritin 15k, lactate dehydrogenase 682, Creatinine kinase 553 and WBC 31.1, absolute lymphocyte 0.7, AST 179, ALT 91, ALP 164, Total Bilirubin 6.0, Sodium 123, BUN 130, Creatinine 12.4. Chest X-ray significant for bilateral ground glass opacity, He was admitted to ICU for acute hypoxic respiratory failure. Despite high suspicion, COVID-19 test was negative thrice, including lower respiratory sampling. However, his urine legionella antigen testing was positive. ICU course was complicated by septic shock, renal failure requiring renal replacement therapy, acute liver failure and acute respiratory failure requiring mechanical ventilation and later tracheostomy. He was treated with 14 day course of antibiotics and later weaned off the ventilator. DISCUSSION: Severe legionnaires' disease, though uncommon, has a very similar presentation as COVID-19 pneumonia. Fever, dry cough, shortness of breath, diarrhea being the most common clinical presentation, whereas laboratory findings significant for elevated inflammatory markers including CRP, CK and LDH are noted in both the diseases (1). Liver and renal failure are also equally involved in both the disease. However, severe hyponatremia and elevated WBC count should raise higher suspicion for Legionella than COVID-19. Our patient presented as a diagnostic challenge with many clinical features that resemble both diseases. The early detection of Legionella pneumonia was imperative to our patient's recovery with prompt treatment with empiric antibiotics. First-line diagnostic testing typically occurs by looking for urine antigens, which tests for the most virulent legionella species, L. pneumophila serogroup 1 (2). Although culture diagnosis remains the gold standard and the most specific diagnostic testing, urine antigen testing allows for early diagnosis and earlier tailoring of antibiotics (3). Thus, for all patients with increased suspicion for COVID-19, we recommend co-testing for urine legionella antigen to rule out Legionnaires' pneumonia. CONCLUSIONS: In conclusion, our case report suggests that we should not overlook typical presentations of known diseases even in the midst of a pandemic. It serves as a reminder to continue early testing for treatable diseases, like Legionella, so as to not miss an opportunity to save a life. REFERENCE #1: Huang C Wang Y Li X et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;(published online Jan 24). https://doi.org/10.1016/S0140-6736(20)30183-5 REFERENCE #2: Cunha BA, Burillo A, Bouza E. Legionnaires' disease. Lancet. 2016;387(10016):376-385. doi:10.1016/S0140-6736(15)60078-2 REFERENCE #3: Fields BS, Benson RF, Besser RE. Legionella and Legionnaires' disease: 25 years of investigation. Clin Microbiol Rev. 2002;15(3):506-526. doi:10.1128/cmr.15.3.506-526.2002 DISCLOSURES: No relevant relationships by trisha arno, source=Web Response No relevant relationships by Brian Cuneo, source=Web Response No relevant relationships by Kejal Gandhi, source=Web Response