Genomic characterization of XDR Mycobacterium tuberculosis isolates in Argentina (2006–2015)

Abstract

Tuberculosis (TB), caused by the intracellular bacterium Mycobacterium tuberculosis complex (Mtbc), remains a significant global health challenge, with Mtbc once again being the leading infectious killer worldwide. 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 1.3 million deaths were attributed to TB in 2024 alone. The emergence of multidrug-resistant (MDR) strains, resistant to isoniazid and rifampicin, and extensively drug-resistant (XDR) strains, resistant to rifampicin (and may also be resistant to isoniazid), to at least one fluoroquinolone (levofloxacin or moxifloxacin) and to at least one other Group A drug (bedaquiline or linezolid), further complicates the situation, posing significant challenges for healthcare systems. While the WHO definition of XDR-TB has recently been updated, in this study we applied the classification in effect during the 2006–2015 period, when the isolates were collected and characterized. 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.