A COLORIMETRIC PCR METHOD FOR THE DETECTION OF MYCOBACTERIUM-LEPRAE IN SKIN BIOPSIES FROM LEPROSY PATIENTS

A one-tube nested polymerase chain reaction (PCR) method for the diagn osis of paucibacillary leprosy was developed using the repetitive RLEP sequence as a target. Detection of the PCR products was simplified by the adaptation of a colorimetric method. The test was specific for My cobacterium leprae, and the sensitivity of the assay was 1 fg of purif ied genomic M. leprae DNA (less than one genome). Complete concordance was seen between the development of color and resolution on agarose g els. The results of frozen skin sections from untreated patients showe d that the assay could detect 100% of multibacillary samples [bacteria l index (BI) of 2 or more] and 69% and 70% of the samples with BIs of 1 and 0, respectively. The use of one-tube nested PCR in assessing the effectiveness of multidrug therapy (MDT) in leprosy also was determin ed. The simplified colorimetric assay was found to be sensitive, rapid and specific, and is suitable for use in routing diagnostic laborator ies.