The effect of corticosteroids usage on bacterial killing, clearance and nerve damage in leprosy; Part 3 – Study of two comparable groups of 100 multibacillary (MB) patients each, treated with MDT + steroids vs MDT alone, assessed at 6 months post – release from 12 months MDT

Abstract

To investigate effects of therapeutic usage of corticosteroids on M. leprae killing and clearance, on clearance of granuloma and on nerve damage in multibacillary (MB) leprosy patients. From a cohort of 400 untreated MB patients, a comparable group of 100 each receiving MDT + steroids (group A) vs MDT alone (group B) were assessed at 18 months as compared to month zero with respect to clinical and granuloma regression, M. leprae killing and clearance, and nerve functions. Analysis was performed using SPSS version 10.0. The significance of association was tested using Chi square and Fisher's exact tests. Regression of lesions assessed clinically and by histopathology was seen in 52% and 53% patients in group A and 46% and 63% in B respectively (P not significant). Clearance of bacteria assessed by bacteriological index (BI) in slit skin smears (SSS) and extent and intensity of antigen using anti-BCG staining were also comparable in the two groups. Multiplication of M. leprae in the mouse foot pad (MFP) indicating the presence of viable bacilli was seen in 14% and 16% of SSS positive BL-LLs patients in groups A and B respectively (P not significant). The occurrence of viable M. leprae was higher among patients with repeat reaction (19%) than single (11%). Using clinical tests (nerve palpation, monofilament and voluntary muscle testing), the proportion of sensory and motor nerves showing improvement or deterioration were similar in the two groups. However using nerve conduction studies, the overall proportion of nerves showing deterioration (22%) was significantly higher than improvement (9%) (P < 0.001). Treatment with MDT + corticosteroids does not adversely affect the clearance of granuloma, M. leprae and/or its antigens and M. leprae killing. However the continued presence of viable bacteria in > 14% of BL-LLs patients indicate that 12 months of MDT may be insufficient for complete bacterial killing. In both groups nerve conduction studies indicated that deterioration of nerves was high suggesting, MDT + corticosteroids was not very efficacious in the prevention or reversal of nerve damage. A better immuno-modulatory drug or a modified corticosteroid regime is needed.