This study investigates the genomic characteristics of extensively drug-resistant (XDR) Mycobacterium tuberculosis strains isolated in Argentina between 2006 and 2015. XDR TB, resistant to both first-line and second-line drugs, poses a significant health threat. By sequencing the genomes of clinical isolates, the study identifies mutations associated with drug resistance, maps genetic diversity, and examines the spread and transmission of resistant strains.

Tuberculosis (TB), caused by the intracellular bacterium Mycobacterium tuberculosis (Mtb), remains a significant global health challenge, with Mtb being the second leading infectious killer worldwide, following COVID-19. Despite over a century of research, the disease continues to pose a major threat, with an estimated one-fourth of the global population latently infected. According to the World Health Organization (WHO), approximately 1.25 million deaths were attributed to TB in 2023 alone. The emergence of multidrug-resistant (MDR) strains, resistant to isoniazid and rifampin, and extensively drug-resistant (XDR) strains, resistant to isoniazid, rifampin, a fluoroquinolone, and a second-line injectable aminoglycoside, further complicates the situation, posing significant challenges for healthcare systems. In Argentina, TB burden is moderate compared to other countries, with approximately 10,500 new cases and 1,000 deaths reported annually. While standard therapy is generally effective, XDR Mtb infections require prolonged and costly treatment and are often associated with a guarded prognosis.