Co-infection with Mycobacterium tuberculosis and Nocardia farcinica in a COPD patient: a case report

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a common respiratory disease characterized by persistent airflow limitation. Infection with either Mycobacterium tuberculosis or Nocardia in COPD patients has been reported. However, co-infection with Mycobacterium tuberculosis and Nocardia is rare. Herein, we described such a patient with COPD in a primary hospital, and the diagnosis process. CASE PRESENTATION: A 79-year-old female farmer with COPD was consecutively admitted to two hospitals with chief complaints of worsening cough, sputum and gasping since January10, 2022. Microbiological examination was not performed at the first hospital due to unknown reasons, and empirical antibiotic treatment was not effective. The patient was subsequently referred to our hospital. After screening the source of infection and the pathogen, she was diagnosed with tuberculosis. However, the patient did not benefit from antituberculosis treatment, with no remission of respiratory tract symptoms. Cerebrospinal fluid and bronchoalveolar lavage fluid specimens were subsequently sent for microbiological examination. The results indicated Mycobacterium tuberculosis and Nocardia.spp. After four days of bacterial culture, Nocardia.spp grew on medium, and Nocardia.farcinica was identified by the MALDI-TOF MS system and 16 s RNA. The patient was prescribed trimethoprim sulfamethoxazole (TMP/SMX) in combination with anti-tuberculosis drugs to treat the co-infection. She showed gradual improvement and was discharged from the hospital on February 19, 2022. However, the follow-up results were unclear. CONCLUSIONS: Co-infection with Nocardia and Mycobacterium tuberculosis should be considered in COPD patients. Repeated microbiological and microscopy examinations are essential in primary hospitals.