Comparison of polymerase chain reaction with standard methods in the diagnosis of Mycobacterium tuberculosis infection

The polymerase chain reaction (PCR) method was evaluated in the detection of Mycobacterium tuberculosis in comparison with direct microscopy and culture procedures including the standard radiometric system (Bactec). Amplified DNA fragments from clinical samples were analyzed by dot-blot and non-radioactive oligonucleotide hybridization techniques or by agarose gel electrophoresis. The results revealed nested PCR to be the method of choice. The combination of three culture methods could detect Mycobacterium tuberculosis in only 79% of PCR-positive cases. The mean time required to achieve a positive culture result was 17 days in contrast to the PCR method requiring only two to three days. The nested PCR assay provided rapid and reliable results allowing a definitive diagnosis particularly in a number of samples which were negative on culture.