The host-pathogen-environment triad: Lessons learned through the study of the multidrug-resistant Mycobacterium...

Area of Science:

• Microbiology
• Epidemiology
• Immunology

Background:

• Multidrug-resistant tuberculosis (MDR-TB) poses a significant global health challenge.
• Drug-resistant Mycobacterium tuberculosis strains were once thought to have reduced fitness, limiting outbreaks.
• However, certain genotypes, like Argentina's M strain, demonstrate high transmissibility and cause extensive outbreaks.

Purpose of the Study:

• To review multidisciplinary research on the epidemiological, microbiological, and immunological aspects of the M strain of MDR-TB in Argentina.
• To understand the factors contributing to the M strain's successful transmission and large outbreak in Latin America.

Main Methods:

• Review of epidemiological data on the M strain's expansion and decline.
• Analysis of microbiological factors, including drug resistance and fitness costs.
• Examination of immunological responses, specifically Th1/Th17 profiles.
• Assessment of host-related stress resistance.

Main Results:

• The M strain exhibits unaltered virulence, low Th1/Th17 immune response, and minimal fitness cost associated with drug resistance.
• High resistance to host-related stress contributes to its successful transmission.
• Incident cases of M strain MDR-TB declined significantly in the early 2000s and stabilized.

Conclusions:

• The M strain's success is attributed to a combination of biological and host-related factors.
• Improvements in MDR-TB management, diagnosis, and treatment, alongside societal factors, aided outbreak containment.
• Sustained public health interventions are crucial to prevent the resurgence of this MDR-TB strain.