A strategic obstacle to the improvement of tuberculosis (TB) control is the lack of inexpensive and simple techniques that can replace the slow and laborious conventional methods for diagnosing TB and detecting drug resistance. However, there are newer, more appropriate methodologies that warrant further evaluation. This concerted action (CA) will develop, adapt and evaluate some of these promising new tools. It will build upon collaborations that have developed between a network of European researchers and their Latin America colleagues. Preliminary studies by this group have begun to address some of the objectives in this CA, and the work outlined will expand these collaborations to develop useful and appropriate methodologies. This project will test them in multicentre pilot studies, modify them where necessary and run prospective clinical trials in high endemic TB areas for accuracy, cost, ease of implementation and impact on TB control.
The objectives are:
1) to develop, standardise and evaluate new methods for tuberculosis
diagnosis, including improvements in microscopy, rapid culture techniques,
serological markers, rapid speciation, and diagnosis of animal mycobacteroses of
2) to develop, standardise and evaluate new methods for the detection of rifampicin resistance as a surrogate marker for MDR-TB
3) to design simple, rapid and inexpensive methods for drug susceptibility testing of M. tuberculosis. Sensitivity, specificity and predictive values will be determined by comparison with the conventional proportion method
4) to extend initial molecular and traditional epidemiological studies on Latin American MDR-TB strains in order to delineate transmission patterns.
The project contains two main areas: diagnosis and detection of drug resistance. The diagnostic component is multidisciplinary, involving new and improved methods for detection, cultivation, and identification of M. tuberculosis. In preliminary studies done by the partners, encouraging results were obtained with several techniques, which will be further evaluated and validated against conventional methodologies. These are a simple and inexpensive method of cultivation employing a thin layer of agar, a simple and direct method of cultivation appropriate for field conditions, and a rapid molecular method of species identification. It will also investigate additional diagnostic strategies: an improved microscopical detection, various M. tuberculosis antigens for their diagnostic value in a serological test, and, since M. bovis TB can be transmitted to humans and has a distinct drug susceptibility, the diagnosing of bovine TB. The second component will develop and evaluate methods for the rapid detection of drug resistant TB, using resistance to rifampicin (RIF) as a marker for MDR-TB. These will include Rifoligotyping evaluation and adaptation for direct use with clinical samples, RIF added into the thin-layer agar format as a direct test for resistance, the luciferase phage test adapted as a rapid direct test for RIF resistance, and exploring colorimetric methods for use on solid media containing RIF. This component will also evaluate faster, easier and more accurate methods for drug susceptibility testing, including second-line and newer anti-tuberculosis drugs. Rapid colorimetric methods will be used for detecting bacterial growth in an ELISA format conventional culture techniques adapted to a multi-well plate. A database of MDR genotypes for Latin America will be created, and will include traditional epidemiologic information so that transmission patterns can be delineated.
1. Development of various techniques into inexpensive, simple, accurate and
2. Testing in multi-centre pilot studies and modifying where necessary.
3. Most promising tools evaluated in prospective clinical trials in TB endemic areas.
4. The concerted action will recommend methods for improved TB diagnosis, drug resistance detection and drug susceptibility testing.
5. Delineation of transmission patterns of MDR-TB in Latin America.
Instituut voor Tropische Geneeskunde
Tel: +32 3 247 6317
Fax: +32 3 247 6333