Immunization with BCG delays the onset of footpad swelling and reduces bacillary growth in <i>M. ulcerans</i> infected mice.

<p>Mice were either non-immunized (•) or immunized with BCG (○) two months before challenge. All mice were infected in the footpad with 4 log₁₀ CFU of <i>M. ulcerans</i> 98–912. (A) Footpad swelling was monitored throughout the experimental infection (<i>n</i> = 10). The onset of footpad swelling was considered at 2.60 mm, after which mice progressed to ulceration of the footpad. For ethical reasons, mice were sacrificed upon onset of footpad ulceration. (B) Infected footpads of BCG immunized mice (white bar) or non-immunized mice (black bar) were harvested at day 52 post-infection and processed for CFU count. Bars represent the mean ± SEM (<i>n</i> = 5) log₁₀ CFU/footpad. Statistical significance was calculated with Student's <i>t</i> test (***<i>p</i><0.001).