Comparison of the Myobacterium tuberculosis with the conventional methods

Abstract

Polymerase chain reaction (PCR), due to its faster response than culture was used for the diagnosis of Mycobacterium tuberculosis. Amplification reactions were performed using primers that amplify a 123 bp fragment of Insertion Sequence 6110 (IS6110) specific to M. tuberculosis. A total of 64 samples were tested by PCR. The type (number) of specimens tested as follows: sputum (31), urine (20), perisentez (5), torosentez (4), peritoneal fluid (3) and bronchial washing (1). Sputum samples were decontaminated by N-acetyl-L-cysteine-NaOH, other samples were decontaminated by NaOH-Na citrate method. The DNA used in PCR was obtained by boiling, 33 samples were found positive with PCR and 30 samples were negative with PCR, 30 samples were smear positive and 30 samples were smear negative, 17 samples were culture positive and 30 samples were culture negative. The sensitivity and specificity were 94% and 79%, respectively. Polymerase chain reaction run with the DNA isolated from standard M. tuberculosis strain H37Rq was working normally in the presence of DNAs (less than 1 ?g) of Escherichia coli and Staphylococcus aureus. The detection limit for PCR was determined by making serial dilutions of DNA from the standard M. tuberculosis H37Rq strain. The detection limit of M. tuberculosis H37Rq strain was found to be as low as ?8 M. tuberculosis genome equivalents of DNA in biological samples.