Posted by: Glow-worm PJ17 OCT 2012
Increasing resistance to drugs for tuberculosis (TB) is a major health problem worldwide. The most commonly used agents, isoniazid and rifampicin, are often no longer effective.
TB is both preventable and curable, but bad management and misdiagnosis have led to the development of resistance. In poor areas, health services may be underfunded, and medical staff undertrained and under-resourced. Treatment can then fall short through lack of follow-up, leading to the development of drug-resistant strains. Globally, resistant cases make up only 5 per cent of the total, but it is estimated that one undiagnosed case can infect up to 10 others in one year.
TB remains epidemic in developing countries, accounting for 1.4 million deaths in 2010, and the combination of HIV and TB has proved catastrophic.
However, a recent survey by scientists in Switzerland has reported that a natural product secreted by the soil bacterium Dactylosporangium fulvum shows promising activity against Mycobacterium tuberculosis, the causative agent in tuberculosis. The natural antibiotic, named pyridomycin, is active against many types of M tuberculosis that no longer respond to treatment with the front-line drug isoniazid. M tuberculosis is also a soil-borne agent, and it is thought that the pyridomycin evolved in D fulvum as part of a protective mechanism against other organisms sharing its habitat. Researchers have identified an enzyme, InhA, which is the principal target for both pyridomycin and isoniazid, but pyridomycin binds to a different site, involving a different sequence of molecular events. Tests have shown that pyridomycin leads to the depletion of fatty acids of the pathogenic cell wall. It is hoped that the findings may lead to the development of pyridomycin or related agents as a treatment for drug-resistant tuberculosis.