Enzymatic DNA amplification (PCR) in the diagnosis of extrapulmonary Mycobacterium tuberculosis infection

A polymerase chain reaction able to amplify Mycobacterium tuberculosis DNA from clinical samples of extra-pulmonary origin is described. The PCR amplified a 294 base pair DNA fragment spanning positions 5'-782 to 3'-1075 of the 65 kDa M. tuberculosis antigen gene. The procedure enables amplification of target DNA at quantities as low as 1 pg of purified material and less than 1000 mycobacteria present in clinical samples. The reaction amplifies M. tuberculosis DNA as well as Mycobacterium bovis BCG DNA. In 34 extra-pulmonary clinical samples studied, 18 rendered positive results and two false-negative results; compared to classical diagnostic procedures, the sensitivity was 90% and specificity 100%. The PCR approach to diagnosis of tuberculosis of extra-pulmonary origin is a valid diagnostic alternative to classical procedures.