[Sulfone-resistance of Mycobacterium leprae--monotherapy with diaminodiphenylsulfone--the value of triple-drug combinations].

While the emergence of drug resistance in Mycobacterium leprae was foreseen and known for a long time, it is now presented as a tragedy jeopardizing leprosy control through monotherapy. This resistance has been mainly reported in the United States. It is not observed in other parts of the world. In our opinion, the unfavorable observations made at present result from an incorrect implementation of dapsone (DDS) therapy in the patients, resulting in low sulfone blood levels, as a consequence of the use of complex disubstituted sulfones, insufficient daily dapsone dosages, irregular or noncompliance to treatment, premature interruption of treatment, etc. Two measures are required in order to prevent the emergence of primary or secondary resistance to dapsone in M. leprae. First, it is necessary to go back to the previous regimen of 200 mg dapsone daily in an adult. It yields the "maximum tolerated effective dosage." It should never have been rejected in favor of 100 mg daily as currently recommended at the moment. The second measure is the implementation of multiple drug therapy (MDT), using concurrently DDS in association with rifampin and clofazimine. This is a logical and rational approach, at least from a theoretical point of view. However, MDT is most unfortunately quite expensive and therefore inapplicable in most countries with high prevalence, since they are poor and underdeveloped. Implementation of MDT also raises great problems, since dosages have to be strictly adhered to in order to prevent a potentially catastrophic emergence of multiple drug resistance in M. leprae.