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Experimental Cocktail May Speed Up Cure Of Drug-Resistant TB

An Indian woman takes tuberculosis pills at a clinic in Mumbai. More than 700 Indians die from TB each day. That's one death every two minutes.
Pal Pillai
AFP/Getty Images
An Indian woman takes tuberculosis pills at a clinic in Mumbai. More than 700 Indians die from TB each day. That's one death every two minutes.

It's been a long time coming — nearly a half century. But the world is finally close to gaining a new weapon against a growing problem: drug-resistant tuberculosis.

Over the past few decades, TB has quietly evolved into dangerous forms that can't be stopped with traditional antibiotics. Now nearly a half million people around the globe are infected with these deadly strains of thebacteria.

Curing drug-resistant TB takes up to two years. It costs thousands of dollars in developing countries and hundreds of thousands here in the U.S. Even then, patients in poor places have only about a 50 percent chance of surviving.

By contrast, regular TB is relatively easy to stop. Curing an infection takes only a few months. And drugs cost about $20.

Now in an experimental test, a new combination of three drugs — two old and one new — was better at clearing up drug-resistant TB than current treatment regimes, scientists reported Monday at the International AIDS Conference in Melbourne.

The trial was small. It included only 26 people with drug-resistant TB and 181 with regular TB. And the trial lasted only eight weeks.

But the results were promising. They suggest that the experimental therapy could cure tough TB infections in about four to six months, scientists from the nonprofit TB Alliance said at the conference.

The new treatment is called PaMZ, after the three antibiotics used: moxifloxacin, pyrazinamide and PA-824 (the experimental drug).

In the study, 71 percent of the people treated with PaMZ had no identifiable TB bacteria in their sputum (the mucus from the lungs)after two months of therapy. By contrast, only 38 percent of those given the standard therapy had cleared the bacteria after two months.

But here's the key finding: Patients with drug-resistant TB did just as well with PaMZas those with regular TB.

"This all points to the new regimen being better than the standard therapy," Dr. Mel Spigelman of TB Alliance told The Scientist.

Since the trial ended after eight weeks, Spigelman and his colleagues still don't know if the drug cocktail actually wipes out drug-resistant TB in the long haul. So it will be years before it's approved and available.

But the positive findings are a step in the right direction. And now Spigelman and his colleagues can start a larger, longer trial with the new drug cocktail.

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Michaeleen Doucleff, PhD, is a correspondent for NPR's Science Desk. For nearly a decade, she has been reporting for the radio and the web for NPR's global health outlet, Goats and Soda. Doucleff focuses on disease outbreaks, cross-cultural parenting, and women and children's health.