Scientists have developed a new technique to detect tuberculosis bacteria which survive the treatment, paving the way for effectively treating TB bacilli resistant to antibodies.

Researchers from the Antwerp Institute of Tropical Medicine have created a simple technique of Fluorescein diacetate staining, which only stains living tuberculosis bacilli (and not dead ones) which can immediately tell if resistant bacilli survived after treatment.

Tuberculosis bacilli have become resistant against major antibiotics. According to World Health Organization (WHO) estimates, only 11 per cent of multiresistant cases were discovered in 2009.

Checking smears under the microscope still is the recommended technique for TB screening, but it cannot differentiate between living and dead bacilli.

It is therefore not clear whether you are looking at the cadavers of a successful treatment, or at resistant survivors. Only if the numbers after a long wait still don't fall, you know you are dealing with a resistant strain. But all that time the patient has remained contagious, the researchers said in a statement.

Armand Van Deun and colleagues in Bangladesh gave a new application to a forgotten technique: vital staining with fluorescein diacetate (FDA). It only stains living TB bacilli, so one immediately sees those bacilli escaping treatment.

The scientists improved the detection of the luminous bacilli by replacing the classical fluorescence microscope with its LED counterpart.

This simple test allows, also in resource-limited labs, to detect a high number of resistant TB bacilli that otherwise would have been discovered too late or not at all.

The study was published in the International Journal of Tuberculosis and Lung Disease.