A San Antonio researcher says a study he worked on may change the way one type of tuberculosis is treated, and that may lead to a decrease in drug resistance.
Professor Deepak Kaushal, Ph.D., is the director of the Southwest National Primate Research Center at Texas Biomedical Research Institute and was a lead investigator on this study in which they tested a new drug regimen to see if it effectively treats latent tuberculosis. That's the kind of TB that doesn't make you sick until something, usually another illness, activates it. He said they wanted to confirm that the new regimen was effective because it is much easier on patients and could lead to more of them finishing their treatment.
People who don’t finish their treatments can go on to develop resistance to the medications that treat the disease, Kaushal said, and that is common with the treatment that has long been used for latent TB.
“Because you have to take between four to 16 pills for six months, in some cases nine to 12 months. And you can imagine any human taking that many pills — toxic drugs — for six to 12 months, that's going to lead to noncompliance and that leads to drug resistance,” Kaushal said.
The study involved non-human primates — rhesus macaques — infected with latent tuberculosis. The macaques were infected using a new animal model that may change the way latent TB is studied. The scientists created a model of latent TB that could approximate, in the macaques, what happens when a person is infected with the bacteria that causes TB, but does not develop active disease.
Kaushal said once the macaques were infected with latent TB, they then treated half of them with a combination of two classes of antibiotics for three months. They did not treat the other half.
Then, researchers infected all of the animals with Simian immunodeficiency virus, SIV, which is similar to HIV in humans. HIV is one of the viruses that activates latent TB in humans, so they wanted to test whether the new drug regimen cleared the bacteria that causes TB from the macaques' lungs by exposing them to SIV. None of the treated macaques developed TB. Several of the untreated macaques did.
That is evidence the two drug regimen works, Kaushal said, and it’s exciting. He said he enjoys doing the kind of research that has almost immediate, real-world implications.
“This isn't research that's going to stay inside the lab, in cells and tissues and model systems for ten more years,” he said. “This is research that will likely have impact next year or the year after that.”
This study was conducted at Tulane University and Emory University as part of the Tuberculosis Research Units Network and was published in the American Journal for Respiratory Clinical Care Medicine.