Antimicrobial resistance in leprosy: results of the first prospective open survey conducted by a WHO surveillance network for the period 2009-2015.

OBJECTIVES: antimicrobial resistance (AMR) is a priority for surveillance in bacterial infections. For leprosy, AMR could not be assessed so far since Mycobacterium leprae does not grow in vitro. We aim to obtain AMR data using molecular detection of resistance genes and to conduct a prospective open survey of resistance to antileprosy drugs in endemic countries through a WHO surveillance network.

METHODS: From 2009 to 2015, multi-bacillary leprosy cases at sentinel sites of 19 countries, were studied for resistance to rifampicin, dapsone and ofloxacin by PCR sequencing of the drug resistance determining regions (DRDR) of the genes rpoB, folP1 and gyrA.

RESULTS: Among 1932 (1143 relapse and 789 new) cases studied, 154 (8.0%) M. leprae strains were found with mutations conferring resistance showing 182 resistance traits (74 for rifampicin, 87 for dapsone, and 21 for ofloxacin). Twenty cases showed rifampicin and dapsone resistance, four showed ofloxacin and dapsone resistance, but no cases were resistant to rifampicin and ofloxacin. Rifampicin resistance was observed among relapses (58/1143, 5.1%) and new cases (16/789, 2.0 %) in twelve countries. India, Brazil and Colombia reported more than five rifampicin-resistant cases.

CONCLUSIONS: This is the first study reporting global data on AMR in leprosy. Rifampicin resistance emerged stressing the expansion of surveillance programs. This is also a call for vigilance on the global use of antimicrobial agents, since ofloxacin resistance probably developed in relation to the general intake of antibiotics for other infections since it is not part of the multidrug combination to treat leprosy.