Abstract: Objective To understand the distribution of strains of Nocardia pseudomallei, infection characteristics and strain resistance of Nocardia pseudomallei, and to provide a basis for the diagnosis and treatment of pulmonary nocardiosis. Method Clinical data of patients diagnosed with pulmonary nocardiosis in Anhui Chest Hospital from January 2021 to December 2023 were retrospectively analysed to analyse the distribution of Nocardia strains, clinical characteristics and drug resistance. Result A total of 22 strains of Nocardia were identified in 21 patients with confirmed pulmonary nocardiosis, including one case with co-infection. The strains included 7 strains (31.8%) of Nocardia gelsenkirchen, 4 strains (18.2%) of Nocardia dermatoglycans, 2 strains (9.1%) of Nocardia abscessus, 2 strains (9.1%) of Nocardia guinea-pig otitis, and 1 strain (4.5%) of each of Nocardia asteroidea, Nocardia Wallace, Nocardia asiatica and Nocardia africanica, and 3 strains (13.6%) could not be identified to the species genus. The average age of the patients was 60.8 years old, and the sex ratio was 1:1.1. Symptoms mainly included cough/sputum (85.7%), chest tightness (38.1%), hemoptysis (28.6%), etc. Chest CT mainly showed bronchial dilatation (57.1%) and plaque (57.1%), etc. Bronchoscopy could visualize and clearly show the typical characteristics of the lesions such as mucus, vesiculocytes, or blood clots in the trachea. The results of drug sensitivity test in 11 cases showed that Nocardia was sensitive to linezolid and amikacin. Conclusion Pulmonary nocardiosis is mostly in middle-aged and elderly patients, with equal proportion of men and women, and the infecting strain is mainly Nocardia gelsenkirchen, which is sensitive to linezolid and amikacin. The clinical manifestations of the patients were not specific, and CT and electronic bronchoscopic manifestations had certain auxiliary diagnostic value.

Key words: Nocardia, Strain identification, Clinical features, Drug resistance