TB kills almost 2 million people a year worldwide, and is increasingly becoming resistant to the antibiotics used to treat it, but there are few new drugs in the pipeline. Doxycycline was introduced in 1967 and is used to treat a wide range of bacterial infections, but until now has not been recognized as effective against TB. The new study, published in the American Journal of Respiratory and Critical Care Medicine, suggests that doxycycline might stop the bacteria from growing and also prevent the disease from damaging the lungs.
Last year, researchers at Imperial College London discovered that TB increases the production of an enzyme called MMP-1, and that this enzyme is responsible for destroying lung tissue.
Now they have found that doxycycline suppresses the production of the tissue-destroying enzyme in TB-infected human cells. They also found that doxycycline directly inhibits the growth of the bacteria in guinea pigs – a surprising result since the drug has been widely used as an antibiotic for over 40 years but has not been considered effective against TB.