Surveillance of drug resistance in TB over the past two decades has informed and guided the response to the multidrug-resistant TB (MDR-TB) epidemic. The Global Project on Anti-TB Drug Resistance Surveillance is the oldest and largest project on surveillance of anti-microbial resistance in the world, reaching a milestone of 20 years of operations in 2014. In 2016, data on resistance to TB drugs were available for 158 countries, accounting for more than 95% of the world’s population and estimated TB cases.
Among new TB cases, which account for most of the global TB burden, an estimated 4.1% have MDR-TB. The proportion is higher among people previously treated for TB, at 19%. While these levels have remained fairly stable over time, some countries do have serious epidemics, particularly in Eastern Europe and central Asia.
Percentage of new TB cases with MDR-TB (Figure 3.20 of the Global tuberculosis report 2017)
Recent innovations in molecular diagnostics are facilitating the shift from periodic surveys to routine surveillance. Rapid molecular tests such as Xpert/MTB RIF assay provide results much faster than conventional methods, do not require sophisticated laboratory infrastructure and decrease cost.
Understanding the background resistance to fluoroquinolones and pyrazinamide is essential for the introduction of new TB treatment regimens. In 2013-2014, surveillance of resistance to these drugs was initiated in seven countries.