Genotyping of Mycobacterium leprae from Brazilian leprosy patients suggests the occurrence of reinfection or of bacterial population shift during disease relapse.

We performed genotyping of Mycobacterium leprae present in skin biopsy samples that were collected during the first and the second disease occurrences from eight leprosy patients, seven of whom were diagnosed as suffering from disease relapse. Sequence analysis of part of the M. leprae rpoB, folP1, gyrB and gyrA genes did not show genetic change that supported the presence of drug-resistant bacilli. However, we observed a synonymous nucleotide change at position 297 of gyrA among five of these patients, one presenting C to T (CgyrAT) and four presenting T to C (TgyrAC) at this position. Additional genotyping by analysis of the four short tandem repeats GAA, GTA9, AT17 and TA18 showed that the gyrA single nucleotide polymorphism change was accompanied by a change in short tandem repeat genotype. Our data suggest that leprosy relapse in these patients, living in an area endemic for leprosy, could be caused by M. leprae with a genotype different from the one that caused initial disease.