Mycobacterium leprae isolates from different sources have identical sequences of the spacer region between the 16S and 23S ribosomal RNA genes.

To test for genotypic variations between different isolates of Mycobacterium leprae, the causative agent of leprosy, the 282 bp spacer region between the 16S and 23S rRNA genes was amplified using PCR, and submitted to single-strand conformation polymorphism (SSCP) analysis. The procedure was optimized using four modified spacer fragments, containing mutations at one, three, four and six positions, respectively. Seventy-five M. leprae isolates from different sources, including isolates from leprosy patients, healthy individuals, armadillos and mouse footpads were identical in the SSCP analysis. DNA sequencing and restriction enzyme analysis performed on four and 40 samples, respectively, confirmed the results obtained with SSCP analysis.