Implications of drug resistance in leprosy: disease course, reactions and the use of novel drugs.

Leprosy remains a significant neglected tropical disease despite the goal of elimination having been achieved in various endemic nations over the past two decades. Reactional episodes complicate the disease course, resulting in deformities and disability. The main aim of treatment is to kill Mycobacterium leprae and decrease the bacterial load, which could help prevent further bacilli transmission. A major concern in breaking the chain of transmission and possibly for recurrent reactions is the role of drug-resistant bacilli. Though some data is available on the background prevalence of drug resistance in leprosy, there is a paucity of studies that look for resistance specifically in leprosy reactions. Administration of long-term steroids or immunosuppressants for chronic and recurrent responses in the presence of drug resistance has the twin effect of perpetuating the multiplication of resistant bacilli and encouraging the dissemination of leprosy. The increasing trend of prescribing second-line drugs for leprosy or type 2 reactions without prior assessment of drug resistance can potentially precipitate a severe public health problem as this can promote the development of resistance to second-line drugs as well. A comprehensive multicenter study, including drug resistance surveillance testing in cases of reactions, is necessary, along with the current measures to stop the spread of leprosy. Here, we have detailed the history of drug resistance in leprosy, given pointers on when to suspect drug resistance, described the role of resistance in reactions, methods of resistance testing, and the management of resistant cases with second-line therapy.