Does DOTS work in populations with drug-resistant tuberculosis?

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Global Health Interventions

Background:

• Directly Observed Therapy, Short-course (DOTS) is the primary global strategy for tuberculosis control.
• The impact of DOTS on tuberculosis transmission in areas with moderate drug-resistant tuberculosis rates remained unclear.

Purpose of the Study:

• To evaluate the effectiveness of DOTS in reducing tuberculosis transmission and incidence in a population with moderate rates of drug resistance.
• To assess the impact of DOTS on both drug-susceptible and drug-resistant tuberculosis cases.

Main Methods:

• A population-based prospective study was conducted in southern Mexico from March 1995 to February 2000.
• Methods included passive case finding, sputum smear microscopy, culture, drug-susceptibility testing, bacterial genotyping, and treatment outcome monitoring.
• Three key indicators were used to monitor tuberculosis transmission: incidence rate, percentage of clustered cases, and rate of primary drug resistance.

Main Results:

• Tuberculosis incidence decreased by 54.4% (from 42.1 to 19.2 per 10^5 population).
• Clustered tuberculosis cases decreased by 62.6% (from 22% to 8%), and primary drug resistance decreased by 84.0% (from 9.4 to 1.5 per 10^5 population).
• Multidrug-resistant tuberculosis rates and treatment failures also significantly decreased, although case-fatality ratios remained higher for multidrug-resistant tuberculosis.

Conclusions:

• DOTS effectively reduced tuberculosis transmission and incidence, even in settings with moderate multidrug-resistant tuberculosis rates.
• While DOTS improved outcomes for both drug-susceptible and drug-resistant tuberculosis, additional interventions are necessary to lower mortality associated with multidrug-resistant strains.
• Drug-susceptibility testing and optimized treatment regimens are recommended to further reduce mortality in multidrug-resistant tuberculosis cases.