Phenotypic methods for screening Mycobacterium tuberculosis or Mycobacterium Ulcerans for susceptibility to therapeutic drugs are necessarily slow due to the protracted growth times of these bacteria. Rapid testing is now possible for the potent antituberculosis drug rifampicin using molecular methods to detect those mutations that confer resistance (1 , 2 ). However, the high cost and requirement for specialized equipment may prohibit the application of this technology in resource-poor settings and there is a need for low-cost, rapid tests that are appropriate for use in low-income countries.