Abstract:Objective To understand the clinical characteristics of pulmonary nocardiosis, analyze antimicrobial resistance of Nocardia, and provide basis for clinical standard diagnosis and treatment. Methods Medical records of patients clinically diagnosed as pulmonary nocardiosis in Henan Chest Hospital from 2016 to 2021 were collected, the isolated strains were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and molecular biological technology, antimicrobial susceptibility testing was performed by micro-broth dilution, clinical characteristics and antimicrobial susceptibility testing results of patients were analyzed. Results There were 42 patients with Nocardia infection, including 24 males and 18 females. 88.1% of the patients had underlying diseases, including bronchiectasis, diabetes, chronic obstructive pulmonary disease, etc. 50.0% of the 42 patients were complicated with other pathogens, 5 of whom were with Aspergillus and 5 with Mycobacterium tuberculosis infection. The imaging findings of pulmonary CT examination of 41 patients were mainly nodular shadow (78.0%) and patchy shadow (58.5%), and 24.4% of patients were accompanied by pleural effusion. In the laboratory examination, 66.7% of the patients had an increase in the percentage of neutrophils, 75.0% of the patients had an increase in C-reactive protein and erythrocyte sedimentation rate, and 54.8% of the patients had hypoproteinemia. Nocardia cyriacigeorgica was the main strain (11 strains) isolated from patients with pulmonary nocardiosis, antimicrobial susceptibility testing results of different Nocardia strains were different, but all strains were susceptible to compound sulfamethoxazole, amikacin and linezolid. Most patients adopted the combined treatment based on sulfonamides, and 83.3% (35 cases) of patients improved and were discharged. Conclusion Pulmonary nocardiosis is easy to occur in patients with bronchiectasis and low immunity, its clinical characteristics are not obviously specific, and is easy to be complicated with infection of Aspergillus, tubercle bacillus and other pathogens, labor-atory should perform antimicrobial susceptibility testing of Nocardia, provide basis for clinical precision treatment.