[Clinical analysis of thirteen cases of pulmonary infection caused by

Objective: To explore the clinical characteristics of patients with pulmonary nocardiosis caused by Nocardia otitidiscaviarum and to enhance understanding of this disease. Methods: A retrospective analysis was conducted on the clinical, imaging, and pathogenic data of 13 patients diagnosed with pulmonary infections caused by Nocardia otitidiscaviarum at Binzhou People's Hospital between January 2022 and December 2024. Results: The patients' age ranged from 42 to 89 (69±13) years. There were 8 females (4 with smoking history) and 5 males (3 with smoking history). The clinical symptoms included cough and sputum production in 8 patients (including 1 with a dry cough), fever in 8 patients, wheezing and chest tightness in 6 patients, and hemoptysis in 3 patients. Computed tomography (CT) scans of the chest showed that 11 patients had involvement of the lower lobe of the left lung, 6 had bilateral lung involvement, 5 presented with involvement of the upper lobe of the right lung, 4 showed changes in both the middle and lower lobes of the right lung, and only 2 had involvement of the upper lobe of the left lung. Of the imaging findings, 8 patients exhibited consolidation shadows, 5 displayed nodule shadows, and 4 had necrotic cavities (with 3 of these located in the lower lobe of the left lung). Additionally, 3 patients were diagnosed with bronchiectasis, 1 with a necrotic lymph node, and 5 with pleural effusion. Microbial study results showed concomitant Aspergillus in 3 cases, Klebsiella pneumoniae in 1, COVID-19 infection in 3, influenza A in 1, and influenza B in 1. All 13 patients demonstrated improvement following treatment with trimethoprim/sulfamethoxazole tablets. Conclusions: Nocardia otitidiscaviarum is a rare form of pulmonary nocardiosis that can occur in individuals with a preserved immune system. This pathogen is associated with more severe clinical manifestations. Furthermore, the risk of Nocardia otitidiscaviarum infections may be exacerbated by the presence of the COVID-19 virus and influenza viruses A and B. Monitoring patients with Aspergillus infection is particularly crucial, as their condition can deteriorate rapidly, posing a considerable danger. Consequently, when patients present with aforementioned risk factors or exhibit specific imaging features, prompt screening and diagnosis using metagenomic next-generation sequencing (mNGS) is essential.