Abstract | April 4, 2022
Legionnaire’s disease mimicking COVID in an immunocompromised patient
Learning Objectives
- Legionnaires disease has many similarities to COVID in the early phase of infection- clinical, laboratory, and radiological;
- While having a high suspicion of COVID is necessitated, it is imperative to consider other etiology such as Legionella, given the significant overlap in clinical presentation.
Introduction: With the current pandemic, the index of suspicion for COVID is high in any patient presenting with respiratory symptoms; physicians tend to have an increased inclination to repeatedly investigate for COVID while encountering negative results. We present a patient with Legionnaires disease, intending to emphasize the marked clinical, laboratory, and radiological similarities to COVID pneumonia.
Case report: A 56-year-old lady presented to the emergency room (ER), with vomiting and diarrhea for 10 days, productive cough, and shortness of breath for 5 days. She had presented with similar symptoms a few days back and was managed with antibiotics. Non-resolving symptoms, lethargy, and confusion prompted revisit. Past history was notable for lupus, for which she was on hydroxychloroquine and prednisolone daily and had 40 pack-year smoking history.
On presentation, she had slight intermittent confusion, febrile 102.9’, tachycardia with heart rate 130 beats/min, tachypnea with respiratory rate of 36 breath/min, normotensive with blood pressure of131/84, and hypoxic with saturation 90% on room air. Auscultation revealed fine inspiratory crepitus in the left lower zone.
Investigations were notable for WBC 7.4, BUN/creatinine 29/0.9, lactic acid 3.2, mild transaminitis, and bilirubin 1.6. Chest x-ray showed extensive left perihilar and basilar airspace opacity. Computed tomography (CT) angiography of the chest confirmed extensive airspace opacity and excluded pulmonary embolus. IV vancomycin and piperacillin-tazobactam were initiated. Initial COVID test was negative.
Clinical deterioration while on antibiotics justified retesting for COVID, which was negative again. Inflammatory markers continued to uptrend and clinical suspicion for COVID remained high despite 2 negative results. The patient’s oxygen requirement increased within 48 hours warranting admission to the ICU for impending respiratory failure.
Legionella urinary antigen was reported positive on day 5; antibiotics changed to levofloxacin resulting in subsequent clinical improvement. Patient required BIPAP support briefly and made a remarkable recovery.
Conclusion: Legionnaires disease is extremely underdiagnosed and underreported. With the pandemic, the reporting declined by 50% in 2020. While having a high suspicion of COVID is necessitated, it is imperative to consider other etiology such as Legionella, given the significant overlap in clinical presentation.
