Trypan blue injected into an area of cutaneous inflammation induced by Staphylococcus aureus failed to drain readily to the tributary lymphatics when the dye was injected as early as 1 hour after the inoculation of the microorganisms.
Trypan blue introduced into an area of cutaneous inflammation induced by Pneumococcus Type I was retained in situ when the dye was injected about 6 or more hours after the inoculation of the bacteria.
When an area of cutaneous inflammation was induced by the inoculation of a culture of Streptococcus hemolyticus, trypan blue injected into it drained readily to the tributary lymphatics for the first 30 hours following the onset of the inflammatory reaction. When the inflammation had lasted for 45 hours or longer, the dye was fixed in situ and failed in most instances to reach readily the tributary lymphatics.
The rapidity of fixation of the dye in the instances given would appear to depend on mechanical obstruction in the form of both a fibrinous network and thrombosed lymphatics or thrombosed lymphatics alone at the site of inflammation.
Inasmuch as staphylococci, pneumococci, and streptococci spread from the site of cutaneous inoculation primarily through lymphatic channels, the difference in the rapidity with which mechanical obstruction is set up in the areas inflamed by them will help to explain the differing invasive abilities of these pyogenic organisms.