Tuberculosis (TB) is one of the leading causes of death in the world today. The World Health Organization (WHO) estimates that in 2006 Mycobacterium tuberculosis caused active disease in 9.2 million people across the globe, killing 1.7 million of them. Although many cases of TB can be cured by available antibiotics, multidrug-resistant TB (MDR-TB) is a major and growing threat worldwide. In 2006 alone nearly half a million new and previously treated TB cases were diagnosed as MDR-TB. The World Health Organization (WHO) estimates the global prevalence of MDR-TB may be as high as 1.5 million cases -- however most agree this is a gross underestimate because so few countries have the laboratory infrastructure to perform drug susceptibility tests. Some strains of TB are resistant to even the second line therapies (extensively drug resistant TB, or XDR-TB). Though also underestimated, XDRTB has now been documented in over 50 countries, including the U.S., England, Japan, Italy, and Norway. We are now seeing the emergence of strains that are totally resistant to treatment (TDR-TB).
The global battle against TB faces serious obstacles. The capacity to rapidly diagnose drug-resistant TB is exceedingly limited, especially in areas with the highest TB burden; true point-of-care testing is non-existent. The treatment for MDR-TB requires strict adherence to the drug regimen, which is nearly impossible to ensure in many developing countries. The supply of quality-assured, second-line anti-tuberculosis drugs is inconsistent and insufficient. The current system for delivering technical assistance to initiate and expand MDR-TB programs is inadequate and underfunded, leaving countries unable to properly and fully integrate the treatment of MDR and XDR-TB into their national TB control strategy. And few new drugs are on the horizon. As a result, it is estimated that less than 4 percent of MDR-TB patients are being treated, and less than two percent receive verifiable quality-assured second-line anti-TB drugs. The pipeline of new TB drugs in development is very limited. Unlike other bacterial infections, TB requires treatment with a cocktail of antibiotics such that multiple new antibiotics are needed making the challenge even greater.
The Institute of Medicine Forum on Drug Discovery, Development, and Translation hosted a one-day, international workshop to assess where we are in the global battle against MDR and XDR-TB, and to consider new strategies that will be urgently required to confront the inevitable rise of TDR-TB.