Diagnosis of Pulmonary tuberculosis by polymerase chain reaction

Abstract

Tuberculosis is on the increase through out the world. At present, the rapid diagnosis of tuberculosis rests on microscopy, however, this technique is insensitive and many cases of tuberculosis can not be confirmed. Also, culture on solid media even with the BACTEC system, is too slow for clinical usefulness. We investigated the use of DNA amplification by the polymerase chain reaction (PCR) for detection ofM. tuberculosis from 50 clinical sputum samples. Half of each sample was processed for smear and culture by standard methods, and the other half was submitted for PCR analysis. The PCR analysis consisted of amplification of a 128-bp segment within the 16S rRNA gene, followed by digestion with restriction enzymes (Hind III and Hae III) and detection by agarose gel electrophoresis. From 50 samples analyzed, 28 samples were positive by smear, 34 samples were positive by culture and 33 samples were positive by PCR. So one sample was positive by culture and negative by PCR. In comparison with culture, the sensitivity and specificity were 98 and 93% respectively for PCR. A good correlation . was observed between the results obtained with the PCR method that we described and other diagnostic tests currently used. Thus PCR amplification of a genome fragment of the I6S rRNA gene is proposed as a specific, rapid and sensitive test for the diagnosis of infection with

Mycobacterium tuberculosis.