Permeability of the Upper Respiratory Mucous Membrane for Bacteria and Their Products.

Abstract

Observations made in this laboratory during the past year or two have disclosed the fact that, in the case of the rabbit at least, bacteria and their products readily and invariably pass through the mucous membrane of the upper air passages when in contact with or growing upon its outer surface. When virulent pneumococci are put into the nares they soon appear in the blood stream and set up a rapidly fatal infection. Less virulent organisms also find their way into general circulation but the resulting infection is frequently overcome and the animal recovers. If killed pneumococci are put into the nares the organisms themselves cannot be demonstrated in the blood but antibodies specific for them soon appear in the plasma, indicating that either the cocci or their products penetrated the mucous membrane. It is possible, of course, that the antibodies may be produced locally and then absorbed. Similar results can be obtained with Bact. lepisepticum—an organism natural to the host. The less virulent strains of this species often occur in the upper air passages of rabbits in the carrier state, but more virulent strains may produce local or general infections. The occurrence of these organisms in the upper air passages under any condition is followed by the appearance of antibodies in the blood serum. Here also a systemic immunity may be produced by putting killed cultures into the nares. An observation along the same line has been made with B. bronchisepticus. This organism occurs very generally in the upper air passages of rabbits, chiefly in the carrier state. Apparently every rabbit exposed to B. bronchisepticus. becomes a carrier, but rabbits raised under special conditions can be kept free of it. The serum of such rabbits does not contain any antibodies for this organism.