Amplification of a species-specific DNA fragment of Mycobacterium tuberculosis and its possible use in diagnosis.

In recent work, a species-specific Mycobacterium tuberculosis DNA fragment was cloned and sequenced. On the basis of its nucleotide sequence, two oligonucleotides were synthesized and used as primers for polymerase chain reaction (PCR) amplification. A 396-bp fragment was specifically amplified from the M. tuberculosis genome. No amplification was observed from any of 10 different mycobacterial strains, included those belonging to the M. tuberculosis complex. Neither was this fragment amplified from genomes of humans or different species of clinically important bacteria. The PCR product was detected by dot blot hybridization even when as little as 10 fg of purified M. tuberculosis DNA was used. This amplification method was subsequently used to detect and identify bacilli in different clinical samples, such as sputum, urine, and cerebrospinal fluid. A good correlation was observed between the results obtained with the PCR method that we describe and other diagnostic tests currently used. Thus, PCR amplification of this genomic fragment is proposed as a specific, rapid, and sensitive test for the diagnosis of infection with M. tuberculosis.