“What Dr. Towsend did next was something that Joseph Lister, despite years spent traveling the world, proving the source of infection and pleading with physicians to sterilize their hands and instruments, had been unable to prevent. As the president lay on the train station floor, one of the most germ-infested environments imaginable, Towsend inserted an unsterilized finger into the would in his back, causing a small hemorrhage, and almost certainly introducing an infection that was far more lethal than Guiteau’s bullet.”
Source: DESTINY OF THE REPUBLIC, 2011