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Journal of Clinical Microbiology, October 2008, p. 3296-3302, Vol. 46, No. 10
0095-1137/08/$08.00+0 doi:10.1128/JCM.02183-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Departamento de Biología Estructural, Instituto Venezolano de Investigaciones Científicas, Altos de Pipe, Estado Miranda, Venezuela,1 Departamento de Medicina Preventiva, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain2
Received 11 November 2007/ Returned for modification 24 January 2008/ Accepted 17 June 2008
The diagnosis of tuberculosis in developing countries still relies on direct sputum examination by light microscopy, a method that is easy to perform and that is widely applied. However, because of its poor sensitivity and requirement for significant labor and training, light microscopy examination detects the bacilli in only 45 to 60% of all people whose specimens are culture positive for Mycobacterium tuberculosis. Therefore, new diagnostic methods that would enable the detection of the undiagnosed infected population and allow the early commencement of antituberculosis treatment are needed. In this work, the potential use of mycobacterial cyan autofluorescence for the detection of Mycobacterium tuberculosis was explored. The tubercle bacilli were easily visualized as brilliant fluorescent bacilli by microscopy and were easily tracked ex vivo during macrophage infection. Assays with seeded sputum and a 96-well microplate reader fluorimeter indicated that <106 bacilli ml–1 of sputum could be detected. Moreover, the use of microplates allowed the examination of only 200 µl of sputum per sample without a loss of sensitivity. Treatment with heat or decontaminating chemical agents did not interfere with the autofluorescence assay; on the contrary, they improved the level of bacterial detection. Autofluorescence for the detection of bacilli is rapid and easy to perform compared to other methodologies and can be performed with minimal training, making this method suitable for implementation in developing countries.
Published ahead of print on 25 June 2008.
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