A unique strain of Mycobacterium tuberculosis and a cautionary tale for users of molecular techniques

Molecular techniques are now widely applied in Australia and elsewhere for the direct detection of Mycobacterium tuberculosis DNA in clinical specimens and culturally enhanced material. All nucleic acid testing methods have the potential to give false negative results due to mutations that may arise at primer or probe binding sites. We describe one such strain of M. tuberculosis that was encountered in 1995 and that has not been encountered in Australia since.