New drug susceptibility test for Mycobacterium tuberculosis using the hybridization protection assay

We developed a novel method for early detection of drug-resistant strains of Mycobacterium tuberculosis by using the hybridization protection assay (HPA). The number of viable bacteria during the incubation period correlated well with the number of relative light units measured by the HPA. In addition, the relative light unit values of susceptible strains on the first, third and fifth days of incubation were significantly different from those of resistant strains for both isoniazid and rifampin. Our results suggest that after isolation of the organism from clinical specimens, drug-resistant strains of M. tuberculosis are accurately detected by the HPA even after 1 day of incubation with the drug.