Rapid identification of Mycobacterium bovis BCG by the detection of the RD1 deletion using a multiplex PCR technique

The BCG vaccine strain cannot, with confidence, be differentiated from othe r members of the Mycobacterium tuberculosis complex on phenotypic tests alo ne. Isolates from clinical sites not associated with vaccination may be con fused with M. tuberculosis. A characteristic of BCG strains is the deletion of the genomic region RD1; detection of this forms the basis of a multiple x polymerase chain reaction (PCR) assay to distinguish BCG strains. In this study, 28 M. tuberculosis complex strains were analysed by the PCR assay. A DNA sequence displaying the characteristic deletion was detected in all e leven of the BCG strains tested and was not found in representatives of oth er members of the complex, including M. bovis. Thus, the assay affords a ra pid, simple and effective method for the discrimination of the BCG vaccine strain from other members of the M. tuberculosis complex.