A new test for diagnosing TB offers a quick and simple alternative to existing three-day methods, according to research published today in the journal Clinical Infectious Diseases.
The study shows that the test, which involves taking three sputum samples from a patient over the course of one day, is just as effective as other more invasive and complicated testing methods, which take three days.
For the new test, patients use a nebuliser to inhale salty water, or hypertonic saline, for twenty minutes. This enables them to produce sputum samples from deep inside the lungs. The samples can then be analysed for traces of mycobacterium tuberculosis, the bacterium which causes most cases of TB.
Other procedures for testing for TB are gastric washing and bronchoscopy with bronchoalveolar lavage. These invasive procedures involve placing tubes in the stomach, to collect samples of mucus swallowed during the night, or the broncial tubes, to try to wash bacteria from infected lung tissue. Patients have to be in hospital for three days to allow these samples to be collected and analysed, delaying the start of treatment.
Such tests are given where patients have symptoms or chest radiography results that suggest the patient might have TB and they are unable to cough up a sputum sample.
The new research, which was carried out by researchers from Imperial College London and Northwick Park Hospital NHS Trust, showed that the new test is just as effective, if not more so, than existing methods for diagnosing TB.
In the 140 people who were examined, use of 3 sputum specimens correctly detected TB in 39% of the patients. Gastric washing detected TB in 30% of the same patient sample. No additional cases were diagnosed in the 21 patients who underwent bronchoscopy.
Dr Robert Davidson, from the Division of Medicine at Imperial College and the Department of Infection and Tropical Medicine at Northwick Park Hospital NHS T
Contact: Laura Gallagher
Imperial College London