A technique that identifies proteins* in the blood particular to tuberculosis (TB) could be used to develop a new diagnostic test for the disease, according to an Online/Article published today (Thursday September 14, 2006) by The Lancet.
At present sputum smear microscopy is often the only available and affordable diagnostic test in most developing countries where TB is endemic, but at best it can detect 50-60% of positive cases. This test, which looks for Mycobacterium tuberculosis, is the diagnostic gold standard as it is sensitive and specific in cases of smear positive tuberculosis but it takes 2-6 weeks to give a result and is not routinely used in countries with high prevalence of TB because of cost.
Sanjeev Krishna (St George's Hospital Medical School, London, UK) and colleagues used a new technique called SELDI-ToF, ** to identify diagnostic combinations of proteins in the blood for TB. They used blood from patients with the disease and controls from several different countries, including the UK, The Gambia, Uganda and Angola, representing at least four ethnic backgrounds.
Using a combination of four biomarkers from this technique, they achieved a diagnostic accuracy for TB of up to 78%. The authors identified two of the possible 20 most discriminatory proteins that could be adapted for use in the field.