Molecular detection of rifampin and ofloxacin resistance for patients who experience relapse of multibacillary leprosy

Molecular detection of rifampin resistance (rpoB analysis) in Mycobacterium leprae was determined for 49 patients who experienced relapse of multibaci llary leprosy and for 34 untreated patients. Molecular detection of ofloxac in resistance (gyrA analysis) was determined for the 12 patients who experi enced relapse and who had received ofloxacin. Results of molecular tests we re compared with the reference susceptibility test in the mouse footpad. Ov erall, the efficiency of molecular detection-that is, positive DNA amplific ation-was 95%, whereas that of the in vivo test was 55% (P < .001). Results of molecular detection and in vivo test were fully concordant when both we re available-that is, for 35 rifampin-sensitive cases of leprosy (no rpoB m utation), 4 ofloxacin-sensitive cases (no gyrA mutation), 11 rifampin-resis tant cases (rpoB missense mutations), and 1 ofloxacin-resistant case (gyrA mutation). rpoB and gyrA analysis appears to be an effective method for det ection of rifampin and ofloxacin resistance in patients with leprosy.