TB-DRUG OLIGOCOLOR

Development of a Molecular Platform for the Simultaneous Detection of Mycobacterium tuberculosis Resistance to Rifampicin and Fluoroquinolones

Framework programme:

6

Call:

3

Project number:

LSHP-CT-2004-516028

EC contribution:

€ 770,856

Duration:

24 months

Type:

STREP

Starting date:

January 2005

Keywords: Tuberculosis, drug resistance, molecular detection, rapid methods, rifampicin, fluoroquinolones

Summary:

The treatment success of drug resistant tuberculosis depends largely on an early diagnosis. A system is proposed for the rapid identification of relevant mutations associated to anti-tuberculosis drug resistance. The platform will be developed for the detection of resistance to rifampicin because the associated mutations are well-defined and circumscribed to a small DNA region. However, it is expected to function as a flexible system able to incorporate the recognition of mutations associated with resistance to other key antituberculosis drugs. A microplate strip format will be used to capture the amplified product of specific target sequences. The technique will be validated for reproducibility and proof of principle in several laboratories under different conditions. A small pre-clinical trial is planned for preliminary evaluation. The application of the developed system to the detection of resistance to fluoroquinolones will also be approached.

Background:

The management and control of multi-drug resistant tuberculosis (MDR TB) relies upon a solid laboratory support. In this project, a versatile and userfriendly molecular platform will be developed and field-tested for the identification of M. tuberculosis and the simultaneous detection of resistance to key anti-tuberculosis agents directly in clinical specimens and/or liquid cultures. The treatment outcome of MDR TB improves consistently when it is recognised and treated early. To maximise the efficacy of a combined drug regimen, drug resistance to first- and second-line drugs should be investigated. A tool on which it would be possible to count simultaneously the anticipated failure of first-line chemotherapy and susceptibility to a major second-line drug would be useful. Phenotypic drug susceptibility assays entail subculture of the isolate in the presence of a set of anti-tuberculosis agents. By requiring only small amounts of bacterial nucleic acids, genotypic approaches may circumvent this hindrance, thus shortening the turnaround time. Moreover, DNA-based technologies can, in principle, be applied directly to the clinical specimen, provided it contains enough bacilli.