DNA-PCR and RT-PCR for the 18-kDa gene of Mycobacterium leprae to assess the efficacy of multi-drug therapy for leprosy.

DNA-PCR and reverse transcription (RT)-PCR for the 18-kDa protein of Mycobacterium leprae were used to examine the efficacy of multi-drug therapy (MDT) in leprosy. MDT was administered for 0-24 months. Fourteen (63.6%) of 22 patients showed positive PCR results after treatment for 12 months and the positive results decreased to 30% after 24 months of MDT. These results did not correlate with the bacterial index (BI) or the IgM antibody titre for the phenolic glycolipid (PGL)-1. One-dimensional densitometric analysis of agarose gels from PCR from the longitudinal study showed a gradual reduction of the 360-bp band after 12-24 months of MDT. RT-PCR for mRNA of the 18-kDa protein successfully tracked bacterial RNA changes in the biopsies and confirmed a decrease in the RNA of M. leprae in patients after MDT for 12 months. Thus, DNA- and RT-PCR for the 18-kDa protein of M. leprae are effective in assessing the efficacy of MDT for leprosy.