BETHLEHEM, Pennsylvania — Tuberculosis, affecting 8.6 million people and killing 1.3 million each year, is the second deadliest disease caused by a single infectious agent, following HIV. Therefore early diagnosis and treatment is vital in the global fight against TB. And with the rise of drug-resistant TB, better methods for drug resistance detection is a priority.
In a report published in the journal Nature Communications, researchers have developed a Tuberculosis breath test that provides rapid information regarding Tuberculosis and drug resistance.
Under standard methods, information about drug resistance typically takes up to six weeks. Rabbits exposed to an inhaled antibiotic returned information within 10 minutes, a dramatic improvement compared to previous methods.
The Tuberculosis breath test features an inhalable form of isoniazid, the antibiotic that is commonly used to treat TB. The antibiotic triggers a reaction from an enzyme within the microbe called KatG, which releases nitrogen. After applying the isoniazid, a breath sample is administered after 5 to 10 minutes and the sample is analyzed by a mass spectrometer.
A positive result, where nitrogen is detected, indicates that the specific TB strain can be treated with isoniazid. A negative result means either the person does not have TB or has an isoniazid-resistant form of TB, which would require alternative treatments that typically have a longer treatment period with the potential for strong side effects.
Currently, tests have only been conducted with rabbits and will require clinical trials to ensure human safety and effectiveness. The test will also most likely require additional refinement and diagnostics to provide a better assessment of the patient’s TB status.
The diagnosis of TB typically requires a wait of one month to 6 weeks for a culture to grow from a patient’s saliva. A few years ago, a new DNA technique called GeneXpert can detect from a sample of saliva whether or not a patient has TB and if so, if it is resistant to a key drug, rifampicin, in approximately 3 hours.
There has been an increase in multi-drug resistant TB, or MDR-TB, due to the long treatment process. Requiring at least 6 months of treatment with multiple drugs, many patients often fail to complete the treatment. MDR-TB accounts for 30 percent of cases in certain countries, making the fight against TB even more difficult.
With TB case reporting uncertain, especially in high-burden countries and with children, early detection tests are vital for increasing accurate reporting on TB cases and can dramatically help those in poverty receive treatment.
– William Ying
Sources: Nature Communications, BBC, The Borgen Project, Yahoo News