Drug Resistance

MDR-TB:

MDR-TB, multidrug-resistant TB, is defined by resistance to the two most commonly used drugs in the current four-drug (or first-line) regimen, isoniazid and rifampin. It is the result of interrupted, erratic, or inadequate TB therapy, and its spread is undermining efforts to control the global TB epidemic. Drug-resistant TB develops when the long, complex, decades-old TB drug regimen is improperly administered, or when people with TB stop taking their medicines before the disease has been fully eradicated from their body. Once a drug-resistant strain has developed, it can be transmitted directly to others just like drug-susceptible TB. There are more than 400,000 cases of drug-resistant TB each year. MDR-TB is such a global health threat because the medicines are very expensive, take years to work, and ultimately inadequate to stop the disease and its spread.

Antimicrobial resistance is dangerous in all its forms, however, MDR-TB yields a global threat to health and economic development. A recent report from a UK parliamentary group stated over the next 35 years, multidrug-resistant tuberculosis will kill 75 million people and could cost the global economy a cumulative $16.7 trillion — the equivalent of the European Union’s annual output.

XDR-TB:

Extensively drug-resistant tuberculosis, or XDR-TB, is a strain of tuberculosis, airborne and infectious, that is resistant to four commonly-used anti-TB drugs. Until the US FDA approval of pretomanid as part of the BPaL regimen, there was no reliable cure for XDR-TB. XDR-TB has been confirmed in 127 countries around the world and represents about six percent of all MDR-TB cases. XDR-TB is emerging as an extremely deadly and costly global health threat that the world must mobilize rapidly to tackle.