WASHINGTON - Researchers have decoded the gene map of a strain of extensively drug-resistant tuberculosis and said yesterday they identified mutations that could help improve treatments.
They also sequenced the genome of another dangerous strain called multidrug-resistant TB, as well as standard tuberculosis bugs, and found a few mutations might explain how some strains evade antibiotics.
"By looking at the genomes of different strains, we can learn how the tuberculosis microbe outwits current drugs and how new drugs might be designed," said Megan Murray of the Broad Institute at Massachusetts Institute of Technology and Harvard University.
The team at Broad, well known for its genome sequencing work, decided to make its findings public immediately instead of waiting to publish the study."It is important that genomic data be made immediately available, particularly to researchers in areas most heavily burdened by disease," said Eric Lander of the institute.
Tuberculosis, or TB, is caused by a bacterium called Mycobacterium tuberculosis. It infects up to 2 billion people, one-third of the world's population, although most have latent, or inactive infections.
In 2005, about 8.8 million people became infected with TB and 1.6 million died of it. It takes months of careful antibiotic treatment to clear the infection.
The microbe can mutate and an estimated 500,000 people globally have multidrug-resistant, or MDR TB, according to the World Health Organization. Standard antibiotics do not affect MDR TB, and patients need special drugs.
Extensively drug-resistant TB, XDR TB for short, is virtually immune to antibiotics and kills up to 85 percent of those infected.
The researchers studied an XDR TB strain that affected hundreds of people in the KwaZulu-Natal province of South Africa.
"Genetic characterization of this strain is essential for developing tools to get this epidemic under control," said Willem Sturm, of the University of KwaZulu-Natal, who worked on the study.
The researchers also identified genes tied to the spread of TB.
"These results also lay the groundwork for the development of a rapid diagnostic test for TB," Murray said.
