Clinical, histopathological and bacteriological study of 52 referral MB cases relapsing after MDT.

Fifty-two BB-LL relapse cases referred to our centre during 1997-2003 were investigated in detail. Twenty-four cases had been treated with extended MB-MDT [until smear negativity (NON-FDT)]. The remaining 28 cases (54%) had received one of the fixed duration regimens (FDT), of whom 11 had 24 months and 6 had 12 months of WHO MB-MDT. Eleven cases had received rifampicin/ofloxacin (RO) treatment. Follow-up slit skin smear reports were available for 41 cases, all but three cases had been smear negative at some point after release from treatment. None of the cases showed any clinical or bacteriological evidence of upgrading, i.e. LL to BT where as downgrading BB to BL occurred in five cases. The duration between cessation of treatment and reappearance of lesions (DCTR) varied from 2 to 15 years. The mean DCTR was longest (9.4 years) for the NON-FDT and 24 months MB-MDT cases. The mean DCTR was significantly lower in the 12 months MB-MDT and RO treated cases (6.8 and 6.2 years, respectively). Four of RO treated cases and four cases with multiple episodes of reaction had DCTR less than 5 years. Inadequate treatment/poor killing of Mycobacterium leprae results in early onset relapse, whereas 'persisting' or 'drug resistant mutants' contribute to late onset relapse.

Viability and drug susceptibility testing of M. leprae using mouse footpad in 37 relapse cases of leprosy.

Mycobacteria leprae isolates obtained from 37 referral relapse cases of leprosy (37 skin and 10 nerve biopsy samples) received during the years 1994-2001, were tested for viability and drug sensitivity in the mouse footpad. A significant M. leprae yield in the footpads of control mice was obtained, with 32/47 (68%) isolates (from 26 cases) thus confirming viability. Of the 28 isolates successfully drug tested, 6 (21%) were resistant to one or more drugs. All except one, were multidrug treated cases (5/24 = 21%). One of the isolates was resistant to all three drugs, i.e., dapsone (di-aminodiphenyl sulphone, DDS), rifampin (RFP), and clofazimine (CLF). Two were resistant to two drugs, i.e., DDS and RFP, and each of the others were mono resistant to DDS, RFP, or CLF. Notably, one of the isolates that showed combined resistance to DDS and RFP was derived from a borderline tuberculoid case. Also, in one case skin and nerve showed that discordance viz: M. leprae derived from skin were resistant to RFP, while those derived from nerve tested sensitive to all three drugs, indicating tissue related difference.