STEWART Cole and his team of scientists at the Pasteur Institute in Paris have discovered that the absence of a single large gene is responsible for making certain strains of tuberculosis bacteria resistant to isoniazid, the principal drug used to treat the disease. (Nature, Vol 358, No 6387) On reinserting the missing gene, in the laboratory, scientists found the bacterium once again became susceptible to the drug.

Cole feels by understanding how the bacterium develops resistance it may be possible to modify the medicine to overcome it. The gene implicated in the experiments makes an enzyme that activates the drug. It may be possible to make a derivative that is toxic to the bacterium.