Pulmonary Nocardiosis in an Immunocompetent Host: A Diagnostic Challenge Requiring Multimodal Evaluation

Pulmonary nocardiosis is a rare opportunistic infection usually affecting immunocompromised hosts but can present in immunocompetent individuals with chronic lung disease, creating diagnostic challenges. We describe the case of a 72-year-old woman with pulmonary fibrosis who had progressive pneumonia unresponsive to standard therapy. Despite multiple non-diagnostic bronchoscopies, cultures from an endobronchial ultrasound-guided transbronchial needle aspiration of a mediastinal lymph node ultimately confirmed Nocardia species. This case underscores the importance of considering nocardiosis in non-resolving pneumonia among immunocompetent patients and highlights the role of multimodal, invasive diagnostics in establishing a timely diagnosis and guiding targeted therapy.