Survey for secondary dapsone and rifampicin resistance in Cuba

A total of 1211 Cuban multibacillary leprosy patients treated for at least 5 years were clinically and bacteriologically examined. They were being treated according to a 2-phase monotherapy regimen with RMP first and DADDS afterwards. On skin-smear examination 50 patients were found positive, of which 9 showed a BI of 3+ or higher at any site. With regard to the clinical status the only cases found with clinical signs of relapse were 5 out of 7 long-standing patients with BI of 4+ and 5+. A 6th patient of this high BI group who showed a good clinical condition, except for a heavy infiltration of both earlobes, was receiving a second RMP course when examined and biopsied for this research. These 9 patients were biopsied and susceptibility tests to RMP and DDS performed. The results showed that in 1 case the Mycobacterium leprae were resistant to both drugs; the organisms from 2 other patients were susceptible to RMP but low-grade resistant to DDS. Those from another patient were susceptible to RMP and fully resistant to DDS. In 3 other cases the bacilli did not multiply in any of the mice but 1 of these strains was from the patient taking a second RMP course, therefore this strain might also be susceptible to RMP and resistant to DDS. In the last 2 cases multiplication was only observed in 2 of the controls and in 1 of the 0.0001% DDS treated mice; therefore, these experiments were not conclusive, and the AFB recovered were inoculated into fresh mice to repeat the tests but these failed to multiply.