DALLAS March 30, 2010 Two new tuberculosis studies by UT Southwestern Medical Center researchers provide good news and bad news about the bacterium that infects nearly a third of the world's population and a disease that kills nearly 2 million people each year.
The good news: A type of blood pressure medication shows promise at overcoming some drug-resistant tuberculosis, at least in the laboratory. The bad news: The Mycobacterium tuberculosis bacterium, which causes the disease, might be resistant to treatment in more people than previously thought.
Dr. Tawanda Gumbo, associate professor of internal medicine at UT Southwestern and senior author of the studies, said the research challenges current thinking about how the TB bacterium works in the body as well as how best to kill it.
His published findings come after the Dallas County Department of Health and Human Services announced this month that while the number of TB cases diagnosed in Dallas County dropped to 195 in 2009 from 219 a year earlier, the county's rate of infection is still 1.5 times higher than the national rate.
In the first study, available online and in the April 15 edition of The Journal of Infectious Diseases, Dr. Gumbo and his colleagues used an experimental apparatus to simulate the way TB bacteria grow in the human lung. When they exposed the bacteria to drugs commonly used to treat the disease ethambutol and isoniazid the bacterial cells activated a cellular mechanism that pumps each drug out of the cells. The pumping action enables the rapid emergence of high-level resistance to the drugs whether administered together as well as individually, Dr. Gumbo said.
"We treat TB with multiple drugs essentially to protect each other from resistance, but yet we've been puzzled with why you find resistance to both drugs together," Dr. Gumbo said. "Our findings make sense it is more efficient from the bacteria's viewpoint to employ t
|Contact: Kristen Holland Shear|
UT Southwestern Medical Center