Abstract: This article reports two cases of brucellosis complicated by central nervous system tuberculosis infection. Such co-infections are clinically rare. Brucella and Mycobacterium tuberculosis can both involve the central nervous system, and their clinical symptoms overlap, making differential diagnosis challenging. Both patients presented to the Affiliated Hospital of Inner Mongolia Medical University with definitive neurological deficits. Metagenomic next-generation sequencing of cerebrospinal fluid ultimately confirmed the diagnosis of central nervous system tuberculosis infection: one case of tuberculous myelitis and one case of acute cerebral infarction secondary to tuberculous meningitis. Serological tests for Brucella were positive in both patients, confirming co-infection with both pathogens. Following combined anti-tuberculosis and anti-brucellosis therapy, both patients showed significant improvement in neurological deficits and laboratory parameters, resulting in a favorable prognosis. Through in-depth analysis of these cases, this article aims to enhance clinicians' awareness of central nervous system tuberculosis co-infection in patients with brucellosis. It emphasizes that when central nervous system infection occurs in brucellosis patients, a high index of suspicion for co-infection with Mycobacterium tuberculosis is warranted. Metagenomic next-generation sequencing is valuable for precise pathogen identification, which is crucial for diagnosis and the development of individualized treatment strategies.

Key words: Brucellosis, Central nervous system, Tuberculosis infection, Metagenomic next-generation sequencing