Identification of Mycobacterium intracellulare by a polymerase chain reaction using species-specific primers.

SETTING

The polymerase chain reaction (PCR) is a rapid and specific method used to amplify a certain DNA fragment. It is applicable to rapid diagnosis of mycobacterial infections. By use of species-specific primers, it is possible to identify mycobacteria by PCR. In this study, a newly constructed primer was tested for specificity for Mycobacterium intracellulare in the PCR.

OBJECTIVE

M. intracellulare is one of the most frequently found bacteria in opportunistic infection in AIDS, and rapid identification of this species is important. The purpose of this study was to construct a primer specific to this species as a suitable tool for identification.

DESIGN

PCR products of M. tuberculosis and M. intracellulare, obtained by using the primers YNP-1 and YNP-2, were sequenced and compared. They showed a difference in the base sequences. A sequence unique to M. intracellulare was used as the primer specific to this species. Various mycobacterial and non-mycobacterial DNAs were used as the primer specific to this species. Various mycobacterial and non-mycobacterial DNAs were used as the template to evaluate the specificity of the newly constructed primers, YNP-7 and YNP-8. Sputum samples were also examined by PCR using the primers.

RESULTS

In total 25 species of culture mycobacterial and non-mycobacterial strains and 76 sputum samples were tested by PCR. Only M. intracellulare DNA was amplified with PCR using the primers YNP-7/8.

CONCLUSION

The specificity of the newly constructed primers for M. intracellulare was confirmed.