[Electron microscopic-radioautographic study of bacterial invasion in severely burned patients].

Wound pieces taken from 3-6 sites at a time during surgical treatment of the wound in 10 patients with thermal burns involving 25-50% of the body surface area, were examined by electron-microscopic radioautography and bacteriologically. The burn wounds were found to contain not only live (RNA-synthesizing) bacteria but also replicating (DNA-synthesizing) bacteria, and to be heterogeneous in terms of bacterial seeding (the largest numbers being present in the scab and the smallest, in the granulation tissue), but not of bacterial species; these were represented in all layers by mixed populations (Pseudomonas aeruginosa, pathogenic Staphylococcus, Proteus), although the deep layers contained more pathogenic and more virulent subpopulations than the more superficial ones. Septic patients had considerably more organisms in all layers of their wounds than nonseptic patients, and contained proliferating organisms in the granulation tissue. The main steps in the penetration of individual microbial species into the circulation were traced out by means of electron-microscopic radioautography.