Equal rates of drug resistance in leprosy cases with relapse and recurrent /chronic type 2 reaction; Time to revise the guidelines for drug resistance testing in leprosy.

BACKGROUND: Leprosy relapse/recurrence is a serious concern especially in a leprosy endemic nation like India. It is believed that bacilli persisting even after multi-drug therapy could cause relapse; recently however drug resistance as a cause for recurrences and chronic erythema nodosum leprosum (ENL) has been speculated. Our objective was to study drug resistance patterns in cases of leprosy relapse and chronic/recurrent ENL's.

METHODOLOGY: This cross-sectional study conducted over a period of 1 year included patients diagnosed as leprosy relapse and those with chronic/recurrent (c/r) ENL. Skin biopsy specimens were subjected to conventional PCR for resistance testing for rifampicin, dapsone and ofloxacin, targeting rpoB, folP and gyrA gene of M.leprae respectively.

RESULTS: A total of 61 patients (25 smear negative) were included in the study. Of these, 37 were diagnosed as leprosy relapse and 24 had c/r ENL. Drug resistance to at least one drug was identified in 10 (16.4%) cases. Rates of drug resistance were 5.4% (2/37) for dapsone, 10.8% (4/37) for rifampicin and 2.7% (1/37) for ofloxacin amongst cases of relapse where as it was 12.5% (3/24) and 8.3% (2/24) for dapsone and rifampicin respectively amongst those with c/rENL.. Multi drug resistance was seen in 3.3% (2/61) patients.

CONCLUSION: Drug resistance rate amongst those with c/rENL was almost equaled that of relapse. Smear negative leprosy relapse cases also had resistance to bactericidal drugs. These findings call for modifications in criteria for testing under leprosy drug resistance surveillance and all cases of relapse and those with recalcitrant c/rENL should be tested.