Publication date: Oct 31, 2025
Mycobacterium avium (M. avium) is emerging as an opportunistic pathogen and has been grouped with the nontuberculosis mycobacteria (NTM). Tuberculosis (TB), caused by Mycobacterium tuberculosis, primarily affects elderly individuals with chronic lung disease and remains one of the leading causes of death in many regions worldwide. Distinguishing between NTM infection and TB is challenging due to similar clinical manifestations and histopathological characteristics. Talaromyces marneffei (T. marneffei) is a pathogenic fungus causing devastating infection, primarily in immunocompromised individuals. Few reports describe disseminated co-infection of M. avium and T. marneffei in HIV-negative persons. Herein, we present a case of an HIV-negative Chinese woman who initially presented with chronic cough, sputum production, and recurrent low-grade fever, which was initially misdiagnosed as TB. After three years of anti-TB treatment, her situation progressed, and she developed multiple subcutaneous abscesses throughout the body, including the brain. Subsequent bacterial culture and molecular diagnostic techniques confirmed the presence of NTM, specifically identified as M. avium. However, despite receiving anti-M. avium therapy remained ineffective until co-infection with T. marneffei was eventually diagnosed. The patient responded well to anti-M. avium therapy combined with antifungal agents after two weeks. Unfortunately, she was lost during the follow-up. Strict adherence to the established clinical diagnostic guidelines for tuberculosis is essential. Early implementation of microbial culture and molecular diagnostic tools plays a critical role in distinguishing TB from NTM infections, particularly in patients who do not respond adequately to anti-tuberculosis therapies. In addition, clinicians should remain vigilant for potential co-infections when inflammatory markers fail to decline or disease progression continues despite adequate anti-infective treatment.