New approach detects resistant tuberculosis faster

Scientists of the Antwerp Institute of Tropical Medicine are using a forgotten technique in order to detect resistant tuberculosis in circumstances where it was otherwise not feasible.

Tuberculosis bacilli that have become resistant against major antibiotics could become a world epidemic if fast and efficient action is not taken, MedicalXpress reports.

During the 19th and 20th centuries, tuberculosis took a billion lives. Only when newly developed antibiotics were developed in the 1950s did it become possible to fight the disease. The treatment was so successful that the World Health Organizationtried to eradicate tuberculosis in 1960.

Mycobacterium tuberculosis, though, is difficult to overcome, demanding treatment with several antibiotics simultaneously for months on end, which is not possible in developing countries. Halted treatments led to the growth of bacilli that were resistant to the antibiotics. In the 1980s, the disease began to spread again, coinciding also with the arrival of AIDS. This made things worse because an infection with one makes you more susceptible to the other.

Today, multiresistant tuberculosis continues to grow and treatment is expensive and time-consuming. The WHO estimates that of the five million or so multiresistant cases of the last decade, only one percent had access to treatment. A 1991 tuberculosis bug was found to be resistant to 11 antibiotics. Some cases report every antibiotic used as being completely useless, MedicalXpress reports.

In 2012 an average of one in 30 new TB cases worldwide was identified as multiresistant. At times, the number spiked to every one in three cases. When patients relapsed after a first cure, the average was one in five being multiresistant. The Soviet Union reported the highest numbers of multiresistant cases.

In order to effectively combat the threat of an epidemic, it is important to recognize multiresistant cases as early as possible. This way, it can be immediately treated with second-line antibiotics that still work. Efforts to identify resistant TB bugs, though, are cumbersome.

High-tech PCR technology offers another approach, but the practice is not feasible in resource-limited countries. The approach is also inefficient, as one would have to cultivate every sample and then treat it with every possible antibiotic in order to survey which antibiotics work for that individual patient.

A new approach, though, by Armand Van Deun and colleagues offers a new application of a long forgotten technique: vital staining with fluorescein dictate. The process only stains living TB bacilli, so one immediately sees those that are escaping treatment. The scientists updated the detection of luminous bacilli by using a new LED microscope instead of a fluorescence microscope. Van Deun worked with colleagues in Bangladesh for four years to test the approach thanks to a grant from the Damien Foundation, according to MedicalXpress.

The approach is effective and can be used in countries with limited resources. When the FDA test failed to detect resistant bacilli, 95 percent of the time more elaborate tests failed to find active bacilli in the patient as well. When the test was positive for living bacilli, the chances were the bacillus was resistant.