Figure 5.

Diffusion of SAH from bacterial colonies in tumors. (a) Colonies of EC-SAH (red) in a 4T1 tumor and associated SAH (green). White arrows indicate areas of colocalization between bacteria and SAH. Bars = 50 µm. (b) Diffusion of SAH (green) was quantified as the distance (r_SAH) of SAH penetration into tissue away from the outer edge (r₀) of bacterial colonies (red). Colocalized pixels appear as yellow. Bar = 25 µm. (c) Distribution of SAH diffusion distances from bacterial colonies (n = 4,743). The average diffusion distance was 6.8 ± 0.3 µm. (d) SAH intensity as a function of colony size. SAH intensity was normalized by the minimum detectable level. A logarithmic fit (red line) was added as an aid to the eye. (Inset) Larger colonies produced more SAH (*P < 0.01). (e) SAH diffusion distance and colony size were inversely related. (Inset) The average distance from small colonies (r₀ < 5 µm) was greater than intermediate (5 < r₀ < 10 µm) and large (r₀ > 10 µm) colonies (*P < 0.001). SAH, Staphylococcus aureus α-hemolysin.