A DNA primer/probe system for the rapid and sensitive detection of Mycobacterium tuberculosis-complex pathogens

Differentiation between Mycobacterium tuberculosis and Mycobacterium bovis by a multiplex-polymerase chain reaction

A multiplex-polymerase chain reaction (PCR) assay, based on one-step amplification and detection of three different mycobacterial genomic fragments, was designed for differentiation between Mycobacterium bovis and Mycobacterium tuberculosis. The oligonucleotide primers were chosen from the groEL gene, present in the genus Mycobacterium sp., from the IS6110 insertion sequence, present in Myco. tuberculosis complex and from the mtp40 gene, identified as a specific-species Myco. tuberculosis genomic fragment. This amplification method allowed the detection of two fragments of 576 and 317 base pairs in Myco. bovis and three fragments of 576, 396 and 317 base pairs in Myco. tuberculosis strains, including atypical strains of Myco. tuberculosis where the copy number of the IS6110 element is low. The multiplex-PCR assay described may be a very useful tool for the rapid and specific differentiation of these related mycobacteria and easy to use in medical and veterinary microbiology laboratories.

Identification and strain differentiation of Mycobacterium species on the basis of DNA 16S-23S spacer region polymorphism

Amplification of the region separating the genes coding for the two rRNA species 16S and 23S was performed to identify 56 mycobacterial strains, belonging to eleven species: Mycobacterium tuberculosis, M. avium, M. kansasii, M. gordonae, M. abscessus, M. fortuitum, M. xenopi, M. bovis, M. bovis/BCG, M. africanum and M. intracellulare. Reproducible amplification patterns were obtained with most species with the exception of M. kansasii which showed heterogeneity, confirming the existence of a genetically distinct subspecies within this species. In addition, we used the amplified products as target DNA for restriction endonuclease digestion and RAPD (randomly amplified polymorphic DNA) analysis to compare strains of M. abscessus, M. tuberculosis and M. avium. The discriminatory power of these two typing methods was higher than when whole genomic DNA is used as target. Our results demonstrate that the two-step approach to identification and typing on the basis of the hypervariability of 16S-23S spacer region is reliable, rapid and simple, and consequently could be an epidemiological tool in clinical laboratories.

Characterization of a DNA probe for detection of Mycobacterium tuberculosis complex in clinical samples by polymerase chain reaction

We cloned and sequenced a DNA fragment from Mycobacterium tuberculosis for use in the identification of members of the M. tuberculosis complex. The DNA probe for culture confirmation had a sensitivity and a specificity of 100%. By using primers developed from this probe, the polymerase chain reaction detected 20 mycobacteria by ethidium bromide staining. This polymerase chain reaction system demonstrated 98% sensitivity and 100% specificity for detection of the M. tuberculosis complex in 200 sputum specimens.

The detection of Mycobacterium tuberculosis in uncultured clinical specimens using the polymerase chain reaction and a non-radioactive DNA probe

A Sal I-Hin dIII restriction fragment from Mycobacterium tuberculosis was found to hybridize specifically with genomic DNA from M. tuberculosis. Primers were designed from the sequence of this fragment and used to amplify uniquely M. tuberculosis-group DNA in a polymerase chain reaction. It is suggested that a combination of these primers and an acetylaminofluorene-labelled probe will prove to be a useful tool for the early diagnosis of tuberculous infections.