Quantitative, Single-Tube, Nested, PCR (QSTN-PCR) for Determining the Antibiotic Susceptibility of Mycobacterium tuberculosis

Rapid drug susceptibility testing for Mycobacterium tuberculosis (Mtb) is imperative in an age when drug resistance is not rare and up to one-third of the world’s population may be infected with this organism (1 ). A sensitive, PCRbased system to test mycobacterial antibiotic susceptibility is one approach to this problem. We reasoned that a quantitative PCR could detect the growth of bacilli by detecting an increase in the amount of mycobacterial DNA. Inclusion of an effective antibiotic in the culture media would prevent bacterial growth and concomitant increase in target DNA, thus distinguishing cultures which were susceptible to an antibiotic from those which were not.