Tuberculosis (TB) remains the deadliest infectious disease worldwide, and the emergence of multidrug-resistant TB (MDR-TB) represents a significant challenge to global health. Recent research conducted by the Swiss Tropical and Public Health Institute (Swiss TPH) reveals that resistance to the newly recommended MDR-TB treatment regimen by the World Health Organization is already spreading among patients. These findings, published in the New England Journal of Medicine, underscore the urgent necessity for enhanced surveillance and infection control measures to combat the rise of antimicrobial resistance.
Concerns Surround Multidrug-Resistant TB
Each year, tuberculosis (TB) affects over 10 million people, making it the foremost infectious disease killer, with an estimated 1.25 million deaths annually. Although TB occurs globally, regions like India, Central Asia, and Southern Africa face especially high rates of infection. Multidrug-resistant TB (MDR-TB) is a growing threat to public health, exacerbating fears about increasing antimicrobial resistance.
The standard treatment for MDR-TB is prolonged, costly, and may lead to serious side effects. In 2022, the World Health Organization (WHO) approved a new 6-month treatment course, known as BPaL(M), based on numerous clinical studies—including TB-PRACTECAL—that demonstrate its enhanced safety and effectiveness.
Monitoring New Treatment Deployment
“While this new regimen represents a major breakthrough for those suffering from MDR-TB, we anticipated challenges in outsmarting Mycobacterium tuberculosis, the bacteria responsible for TB,” explained Sébastien Gagneux, head of the Department of Medical Parasitology and Infection Biology at Swiss TPH and lead author of the study. “It was vital to investigate how the TB bacteria might respond to the widespread application of this new treatment.”
Swiss TPH’s recent study, in cooperation with the National Centre for Tuberculosis and Lung Diseases in Tbilisi, Georgia, was published in the New England Journal of Medicine. It meticulously examined whether drug resistance to the new treatment has arisen since its introduction and whether this resistance is being transmitted between patients.
Transmission Contributes to Over One-Quarter of Resistant Strains
The researchers analyzed nearly 90,000 M. tuberculosis genomes from Georgia and various other countries. They identified 514 strains resistant to TB medications, including both older and newer treatment options. These highly drug-resistant strains were detected in 27 countries across four continents.
Alarmingly, 28% of these strains were passed directly from one patient to another. “We had previously seen informal indications of resistance developing against the new regimen, but we lacked concrete evidence regarding how much of this transmission was fueling the spread of these highly resistant strains,” said Galo A. Goig, a postdoctoral researcher at Swiss TPH and the study’s primary author.
“The positive aspect is that the overall number of these cases remains low. However, the fact that over a quarter of these highly resistant instances arise from patient-to-patient transmission, merely two years after WHO endorsed the new treatment, is concerning,” Goig added.
Need for Enhanced Surveillance and Infection Control
These results carry crucial implications for public health strategies and actions. “The development of these new medications has taken significant time, and to avoid developing drug resistance, it is essential to implement these new regimens alongside strong diagnostics and surveillance systems,” remarked Chloé Loiseau, a postdoctoral researcher at Swiss TPH and co-author of the paper.
The authors stress the importance of upgrading diagnostic tools, improving infection control measures, and establishing effective surveillance systems to prevent the spread of these highly resistant strains, thus ensuring the effectiveness of the new treatment regimen.
Confronting Antimicrobial Resistance
While new TB medications are being developed, health experts express concern that M. tuberculosis will persist in finding ways to bypass these advancements. “The emergence of these highly resistant TB strains exemplifies that antimicrobial resistance is among the most critical challenges to global health today,” noted Gagneux. “We must advance in this ongoing battle between drug innovation and bacterial resistance, taking proactive measures to avert a ‘post-antibiotic era’ for TB and other diseases.”
Understanding Tuberculosis
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. It spreads through the air from one person to another. Symptoms include coughing, chest pain, weight loss, fever, and night sweats. Multidrug-resistant tuberculosis (MDR-TB) arises from bacteria that do not respond to the two most potent first-line TB medications. In 2022, only about 40% of those with MDR-TB were able to access treatment.
