Scientists have found that a drug used to treat malaria may also aid in the treatment of tuberculosis. The ancient Chinese herb, artemisinin, has the potential to shorten how long it takes to treat TB, something that could also fight drug resistance to antibiotics.
Scientists say they don't know yet by how much time artemisinin might shorten a course of standard anti-TB drugs, but experiments in the test tube suggest that it could have a significant impact.
The bacterium that causes tuberculosis can lie dormant for years before taking advantage of a weakened immune system to 'wake up' and spread.
It's believed a significant portion of the world’s population has latent TB. According to the U.S. Centers for Disease Control and Prevention, one-third of the world's population is infected with TB, which killed 1.8 million people in 2015.
Experts say those with the active form of the disease also harbor dormant bacteria, a state in which they are largely resistant to antibiotics. That’s why it takes six months or longer to treat TB with antibiotics.
Now, researchers at Michigan State University have discovered that artemisinin, a mainstay of malaria treatment, prevents the pathogen that causes TB from going into a dormant state, exposing more of the bacteria to the drugs.
Microbiologist Robert Abramovitch is a TB expert. He notes that many people who start taking antibiotics begin to feel better in a few days, as the active bacteria are killed. So they stop taking their pills, potentially causing a resistant strain of tuberculosis to develop.
“It’s the dormant bacteria that take a long time to kill," he stresses. "So if we can kill the dormant bacteria with, let’s say, artemisinin or some of the other compounds we discovered, we can maybe shorten the course of therapy, and by doing that, we can reduce the sorts of clinical behaviors that are driving the evolution of drug resistant strains.”
The finding was published in the journal Nature Chemical Biology.
Abramovitch says TB bacteria need oxygen to thrive. To fight the infection, the body’s immune system lowers oxygen levels. To protect themselves, the bacteria goes dormant.
By disrupting the microbe’s oxygen sensor with artemisinin and five other compounds the team discovered, it doesn’t sense the change, remains active and can be killed by the antibiotics.
Until now, scientists couldn’t distinguish the silent bacteria from the active ones to know whether dormant mycobacterium were being killed by different compounds. Abramovitch and colleagues developed a strain of the pathogen that glows bright green. They found it stopped glowing after artemisinin came into contact with the mycobacteria's oxygen biosensor, presumably dying.
“So we would all see this as an add-on to current therapies as a way to kill another sub-population of the bacteria during the infection,” Abramovitch said, adding that artemisinin could potentially be used with the drug isoniazid, the first line antibiotic used for the treatment of tuberculosis.
