Doctor staining sputum slides in Morocco — the new method is twice as fast

Jad Davenport

[LUSAKA] Researchers have developed a test that halves the time taken to diagnose tuberculosis and allows doctors to identify drug-resistant strains of the bacteria that cause the disease.

They say their test could reduce both the severity and spread of the disease in developing countries.

The method, called 'Microscopic Observation Drug Susceptibility' or 'MODS', is described today (12 October) in the New England Journal of Medicine.

The researchers compared their approach to two existing methods using samples from Peruvians who were suspected of having tuberculosis (TB), were at high risk of TB or were hospital patients with HIV.

The new test was twice as fast as previous ones and could detect smaller amounts of the TB bacterium. It allowed doctors to detect TB bacteria that are resistant to multiple drugs in a third of the time taken by current tests.

Whilst the common TB strain is almost 100 per cent treatable, there are increasing numbers of cases of multi-drug resistant tuberculosis.

Robert Gilman of the Cayetano Heredia University in Peru, who took part in the study, said his colleagues are already sending their test to Africa through a training programme in collaboration with Hadassah University in Jerusalem. Three Ethiopians have been trained to use it so far.

He said smear microscopy, the method recommended by the World Health Organization, is quick but not sensitive — about half of TB cases go undetected and the method provides no information about whether or not the strain of bacterium is resistant to drugs.

Using the new method, TB bacteria are grown in a liquid, where they form characteristic tangles that are easily recognised under a microscope.

Gilman adds that his team's approach would provide the same level of diagnosis in developing countries as is available to patients in industrialised nations.

Almost all of the 2 million people die from TB each year in developing countries.

Link to full paper in New England Journal of Medicine

Reference: New England Journal of Medicine 355, 1525 (2006)