Molecular Dıagnostic Tests Used in the Dıagnosis of Tuberculosis

Abstract

The definitive diagnosis of tuberculosis (TB) is dependent on the isolation, identification and drug susceptibility testing of the causal agent Mycobacterium tuberculosis by cultivation. Smear microscopy has poor sensitivity and culture is slow to yield results. The resurgence of tuberculosis worldwide has been accompanied by an increase in the incidence of multidrug-resistant (MDR) tuberculosis on all continents. At the same time, a number of other nontuberculous mycobacterial (NTM) species are emerging as causes of disease. A quick and correct diagnosis of symptomatic tuberculosis is critical for the control of this serious disease. The nucleic acid amplification techniques (NAATs) and other molecular biology methods (i .e. DNA hybridization, DNA sequencing, etc.) are essential in today's laboratory practices for detection and characterization of mycobacteria. The use of NAATs in the routine detection of mycobacteria allowed a fast and accurate detection of the Mycobacterium species within 24 hours. The methods are widely used for the identification of mycobacteria, detection of the mutations in the resistance genes as well as the molecular epidemiological studies. The availability of new kits, and accumulated experience with nucleic acid amplification techniques for M. tuberculosis detection in most laboratories, have yielded improved sensitivity and specificity of these tests.