South African scientists have devised an electrochemical technique that could provide a quick and easy diagnosis of tuberculosis (TB).   

TB is a highly contagious disease and is often a secondary infection that causes death in many HIV/AIDS infected patients, particularly in south-east Asia and sub-Saharan Africa. Current diagnostic techniques involve culture analysis of phlegm from patients and usually take 4-8 weeks. This leads to delayed diagnosis and hinders prompt patient care, explains Kenneth Ozoemena from the Council for Scientific and Industrial Research in Pretoria and the University of Pretoria, South Africa.   

Ozoemena and colleagues have now developed an immunosensor that could allow easier TB detection. The team modified a gold electrode with mycolic acid, an antigen that forms the cell walls of the TB bacterium. This allows the electrode to recognise antibodies that are present in an infected patient's blood and results in a change in the electrode response.     

By comparison with previous detection methods, the new immunosensors are 100 times more sensitive, says Ozoemena, who is enthusiastic about these results. 'Many people have used electrochemical impedance techniques to detect protein-DNA interactions, but no one has actually considered this technique for TB detection,' he says.
 
Craig Banks, an expert in electrochemical sensors at Manchester Metropolitan University, UK, points out that 'the sensor shows immense potential for a rapid point-of-care test for TB, but further work is required to fully understand the underlying electrochemical principle.' To this end, Ozoemena has already begun to investigate exactly how the antibodies interact with the electrode's surface. He says that he hopes this work will lead to 'the realisation of a clinical device for fast detection of TB that is cheap and easy to operate, even by non-specialists with minimal training.' 

David Sharpe 

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