Pulmonary nocardiosis in West Texas: A case series and literature review

ABSTRACT

Background: Pulmonary nocardiosis is an uncommon but potentially life-threatening opportunistic infection that often presents with nonspecific clinical and radiographic findings, leading to delayed diagnosis. Although classically associated with immunosuppression, it may also occur in patients with chronic lung disease or other predisposing conditions.

Case Presentations: We describe three cases of pulmonary nocardiosis diagnosed at a tertiary referral center in West Texas. Two patients had systemic lupus erythematosus receiving chronic immunosuppressive therapy, while one had interstitial lung disease treated with high-dose corticosteroids. Clinical presentations included dyspnea, cough, pleuritic chest pain, cavitary pulmonary lesions, empyema, and multifocal consolidations. Initial diagnostic evaluations frequently suggested alternative etiologies, including bacterial pneumonia, mycobacterial infection, or invasive fungal disease. Definitive diagnosis was established by microbiological isolation of Nocardia species from empyema fluid or respiratory specimens. Management required prolonged, susceptibility-guided antimicrobial therapy, with some patients requiring surgical intervention or indefinite suppressive treatment because of persistent immunosuppression. All patients demonstrated clinical improvement following targeted therapy.

Discussion: These cases highlight the broad clinical spectrum of pulmonary nocardiosis and reinforce the importance of maintaining a high index of suspicion in immunocompromised patients and individuals with chronic lung disease receiving corticosteroids. The disease frequently mimics tuberculosis, fungal infections, and pulmonary malignancy, making early microbiologic diagnosis essential. Species identification and antimicrobial susceptibility testing are critical to guide individualized therapy and optimize outcomes.

Conclusion: Pulmonary nocardiosis remains a challenging diagnosis because of its heterogeneous presentation and overlap with other pulmonary diseases. Early recognition, prompt microbiological confirmation, evaluation for disseminated infection, and individualized prolonged antimicrobial therapy are essential to improve patient outcomes, particularly in high-risk populations.

Keywords: Nocardia infection, pneumonia, case series