Acute Hypoxic Respiratory Failure Secondary to Pulmonary Nocardiosis: An Unusual Presentation in the Emergency Department

Background: Nocardiosis, a rare but serious infection caused by Gram-positive, aerobic actinomycetes, primarily affects immunocompromised individuals. This report highlights an uncommon case of pulmonary nocardiosis in an immunocompetent patient leading to acute hypoxic respiratory failure. Case Presentation: A 45-year-old male gardener with no significant past medical history presented with acute dyspnea, pleuritic chest pain, fever, night sweats, and weight loss. Physical examination revealed respiratory distress and hypoxia. Imaging showed bilateral alveolar infiltrates and cavitary lesions. Sputum analysis identified Gram-positive branching filamentous bacteria, and Nocardia species were cultured. HIV test was negative. Management: The patient was admitted to the ICU and treated with high-flow oxygen therapy and empirical antibiotics (trimethoprim-sulfamethoxazole TMP-SMX and meropenem). Upon culture results, TMP-SMX was continued, and meropenem was discontinued. The patient showed significant improvement and was discharged on oral TMP-SMX for a six-month course. Discussion: This case underscores the importance of considering pulmonary nocardiosis in acute respiratory failure, even in immunocompetent patients. Early diagnosis and appropriate treatment are crucial for favorable outcomes. Conclusion: Pulmonary nocardiosis can cause severe respiratory symptoms in otherwise healthy individuals. Prompt recognition and treatment are essential to manage this potentially life-threatening condition effectively.