# Case Report: Pulmonary nocardiosis: three case reports and literature review

## TL;DR

This case report and literature review explores three cases of pulmonary nocardiosis and highlights the importance of precise diagnosis and tailored treatment for better outcomes.

## Contribution

The paper introduces a precision diagnosis strategy using bronchoscopy and next-generation sequencing combined with individualized antimicrobial therapy for pulmonary nocardiosis.

## Key findings

- Patients with next-generation sequencing and bronchoscopy showed a trend toward lower mortality.
- Trimethoprim-sulfamethoxazole was the most commonly used treatment regimen.
- Chronic lung diseases and immunosuppression were common comorbidities in pulmonary nocardiosis patients.

## Abstract

Pulmonary nocardiosis is a relatively uncommon opportunistic infection characterized by nonspecific clinical features, often leading to delays in diagnosis and treatment. We describe the clinical data of three confirmed cases of pulmonary Nocardia infection. We also systematically reviewed relevant literature from the PubMed database between January 2015 and September 2025, and performed a pooled analysis of 119 patients. Case 1 involved an elderly patient with bronchiectasis, diagnosed via targeted next-generation sequencing (tNGS) of sputum, who showed significant radiological improvement after treatment with trimethoprim-sulfamethoxazole. Case 2, with coexisting bronchiectasis and chronic obstructive pulmonary disease, was diagnosed by tNGS of bronchoalveolar lavage fluid and switched to linezolid-based combination therapy due to drug intolerance. Case 3 involved a patient with underlying structural lung disease who experienced protracted infection but eventually achieved control following individualized combination antimicrobial therapy and supportive care. Literature analysis revealed a median age of 57 years with a male predominance (55.5%). Common comorbidities included chronic lung diseases (39.5%) and immunosuppression-related conditions (39.5%). Chest CT findings mainly featured consolidation (47.9%) and nodules (41.2%). Diagnosis relied primarily on sputum/airway secretions (48.7%) and bronchoalveolar lavage fluid (42.9%), and 83.2% of patients received regimens containing trimethoprim-sulfamethoxazole. Patients undergoing next-generation sequencing and/or bronchoscopy showed a trend toward lower mortality. This report suggests that a precision pathogen diagnosis strategy centered on bronchoscopy and next-generation sequencing, combined with susceptibility-guided and dynamically adjusted individualized combination antimicrobial therapy, may help improve clinical outcomes in patients with pulmonary nocardiosis. Close monitoring and management of adverse drug reactions are essential during long-term treatment.