Using Electronic-Nose Technology to give rapid and early detection of Mycobacterium Tuberculosis

The World Health Organization (WHO) considers the prevalence of tuberculosis To constitute a global emergency. Some estimates state that one third of the world's population is infected with Mycobacterium tuberculosis with some 9 million new cases developing each year, leading to 2 to 3 million deaths. The usual method of diagnosing TB in developing countries is through the detection of acid-fast bacteria in sputum by direct microscopy examination.



With some care some 60 to 70% of all adults with pulmonary TB can be identified using the Ziehl-Neelsen (ZN) staining procedure, followed by microscopic examination. However such tests are time consuming and demand a lot of the limited laboratory resources in such countries. The resulting demand for a simple, inexpensive and rapid diagnostic test led a number of researchers to use the Bloodhound electronic noses in field trials. These trials met with significant success.



In one study the sensitivity for the detection of culture-proven TB was 89% with a specificity of 91% and the positive and negative predictive values were 88% and 92% respectively. These results were obtained using a 'general purpose' sensor array rather than one populated with sensors selected for their sensitivity to the known VOC markers of this disease. RoboScientific now has a wider array of sensors and is planning to repeat the exercise with an aim of achieving 99% accurate detection and faster diagnostic times.



Research bodies and other interested parties interested in participating in this work are urged to contact the company to discuss the project.


Bovine TB infections in Badgers and Cattle


In the UK the topic of cattle herds being infected with bovine TB is rarely out of the newspapers such is the devastation that can be caused to farming businesses by such infections. Some researchers now estimate that more than 50 million cattle are infected with Mycobacterium bovis worldwide; the potential for huge economic losses is high. Currently the diagnosis of tuberculosis in cattle is done by tuberculin skin testing.



However the continued failure to eradicate bovine TB in the UK is probably due to a reservoir of the infection in badgers although this cannot be quantified as these animals can only be tested after death. The badger and its sett are protected under legislation in the UK and so an accurate in vitro test for badgers is needed urgently to determine the true extent of the reservoir of infection cheaply and without harming badgers. For cattle it would also be desirable to have a rapid, inexpensive on-farm test to complement the existing tests.



Work has been done to evaluate our electronic nose technology to diagnose infection in cattle or badgers with M. bovis, using a serum sample. Samples were taken from both experimentally infected badgers and cattle, as well as naturally infected badgers. In every case the electronic nose was able to discriminate infected animals from controls as early as 3 weeks after infection with M. bovis. The use of RoboScientific electronic nose instruments offers outstanding potential as a sensitive, rapid, and cost-effective means of diagnosing bovine TB infections in cattle and badgers.