Disseminated Mycobacterium szulgai involving lung, lymph nodes and bone: a case report

Nontuberculous mycobacteria (NTM) refer to a large group of mycobacteria other than Mycobacterium tuberculosis complex and Mycobacterium leprae. Mycobacterium szulgai (M. szulgai) is a slow growing species of nontuberculous mycobacteria (NTM), which can cause infection in multiple organs, including the lungs. Using the technique of next-generation sequencing (NGS), we diagnosed disseminated M. szulgai infection in a patient with no obvious immunodeficiency. We report on a 66-year-old female patient who presented with enlarged cervical lymph nodes and an intermittent fever. Imaging showed multiple, enlarged, abnormal lymph nodes, a pulmonary mass and rib lesions that strongly suggested neoplasia. There was no significant improvement in symptoms after intermittent antibiotic treatment. The pathological results of multiple biopsies did not support the diagnosis of tumors. The diagnosis of M. szulgai infection was confirmed by NGS. The patient started standard treatment with clarithromycin, ethambutol, and moxifloxacin in July 2020. Since then and over the 10-month follow-up period, there has been a progressive reduction in the size of the enlarged lymph nodes and lung lesions, and no recurrence of fever or other symptoms. M. szulgai is a potential cause of infection (including of disseminated disease) even in patients with no obvious immunosuppression. The potential usefulness of the NGS of clinical samples should be highlighted.