The significance of a recent Tulane/Yerkes study on eradicating latent tuberculosis in non-human primates may not be apparent at first glance. After all, it used the same antibiotic regimen (isoniazid + rifapentine) that is recommended by the CDC for human use.
But consider whether someone who was exposed to TB in childhood might still have it in their lungs somewhere. It’s difficult to know if treatments get rid of the bacteria completely.
“The antibiotic treatment we used for this study is a new, shorter regimen the CDC recommends for treating humans with latent tuberculosis, but we did not have direct evidence for whether it completely clears latent infection,” says Yerkes/Emory Vaccine Center researcher Jyothi Rengarajan, who was co-principal investigator along with Deepak Kaushal of Tulane. “Our experimental study in macaques showing almost complete sterilization of bacteria after treatment suggests this three-month regimen sterilizes humans as well.”
In an editorial in the same journal, CDC and Johns Hopkins experts call the results “dramatic” and say application of the drug regimen “could presage a major step forward in TB prevention and control.”
Because of their special cell walls and slow metabolism, tuberculosis bacteria can “hibernate” a long time without making people sick. Complicating factors such as HIV infection, diabetes, aging or other diseases can spur them to emerge and cause active disease. In this study, the Tulane/Yerkes researchers used SIV infection (mimicking HIV) to test whether the antibiotic treatment cleared the bacteria from their lungs. More about how the study was conducted here.
This is the first time rhesus macaques were used as a model of latent TB treatment. The researchers say that the model could help them develop shorter courses of treatment for latent TB – the current treatments are lengthy (3 months) and many patients do not finish them. In the United States, we don’t think that much about tuberculosis. Worldwide, it is one of the top ten causes of death and the leading cause from a single infectious agent – above HIV/AIDS.