Pulmonary manifestation of a cutaneous pathogen: a fatal report of Nocardia brasiliensis pneumonia in elderly with no apparent immunocompromised status

Nocardiosis, a rare but potentially life-threatening opportunistic infection, typically affects immunocompromised individuals. However, this report describes an unusual case of primary pulmonary nocardiosis caused by a cutaneous pathogen-Nocardia brasiliensis in a previously healthy, immunocompetent woman. The patient, with a history of chronic obstructive pulmonary disease (COPD), presented with non-specific symptoms including fever, chest pain, productive cough, and progressive dyspnoea, initially leading to a diagnosis of acute exacerbation of COPD with bacterial pneumonia. However, further diagnostic investigation revealed the presence of Nocardia brasiliensis in sputum samples, confirmed by Gram staining and modified Ziehl-Neelsen (ZN) staining. Despite appropriate initial clinical suspicion, the patient was not started on targeted therapy with cotrimoxazole in a timely manner. As a result, her condition rapidly worsened, progressing to multi-organ dysfunction syndrome (MODS), and she succumbed to the infection before effective treatment could be initiated. This case highlights two rare findings: the atypical presentation of pulmonary nocardiosis in an immunocompetent host and its rapid progression, emphasizing the critical importance of timely diagnosis and intervention. This case underscores the diagnostic challenges posed by Nocardia species, which can mimic other pulmonary infections, such as tuberculosis or fungal pneumonia. Given the increasing incidence of nocardiosis, especially in individuals with chronic lung diseases like COPD, heightened clinical awareness, early microbiological diagnosis, and prompt initiation of appropriate antimicrobial therapy is essential to improving patient outcomes and preventing fatality.