[Direct detection of mycobacterium tuberculosis complex in clinical specimens by gen-probe amplified direct test]

The amplified Mycobacterium tuberculosis direct test (MTD) (Gen-Probe Inc., San Diego, CA, USA) is a rapid technique of nucleic acid amplification which can be used directly on processed clinical specimens. It is based on the enzymatic amplification of ribosomal RNA via DNA intermediates, with detection of amplified product by an acridinum-ester-labeled DNA probe. The purpose of this study was to evaluate the clinical utility of this test for diagnosis of tuberculosis by comparing the sensitivity and specificity of the test with acid-fast smear, mycobacterial culture and clinical evaluation. The study included 399 specimens from patients, suspected of Tb which were submitted to the microbiological laboratory of our Institute over a 12 months period. Compared with bacterioscopy, conventional culture on L-J and rapid systems of cultivation (Bactec-450 Tb, MB/Bact, Bactec 960 MGIT) MTD had a sensitivity 93.2% and specificity 98.5%. We conclude, that MTD test which is completed within 6-8 hours, when used rationally, mainly in conjunction with routine smear and culture is a useful, rapid diagnostic test for suspected tuberculosis patients.