Experimental Meningococcal Infection in the Mouse

Abstract

The method described below developed out of a long series of attempts to infect some easily available laboratory animal with gonococcus. To the reader interested in the evolution of technical procedures, it may not seem superfluous to recount briefly the preliminary steps leading to its adoption as a means of studying experimental meningococcal infection. After a fruitless effort to establish gonococcal infection in rabbits and guinea pigs, an attempt was made to adapt a freshly isolated strain of gonococcus to the mouse by rapid animal-to-animal passage without intermediate growth on artificial mediums. To avoid contamination, the peritoneal cavity was chosen as the site of inoculation and exudate was transferred from recently succumbed or moribund mice directly to normal animals within the briefest possible time. It was hoped that in the course of many transfers the strain might acquire virulence for the mouse. During the experiments it was found that multiplication of the organisms failed unless a sufficient quantity of fluid was maintained within the animal's peritoneal cavity. The liquids ordinarily used for suspending inocula?buffered saline, Ringer's and broth?were rapidly absorbed. These facts clearly indicated protein solutions as more suitable vehicles, and various serums, egg albumin, etc. were employed. The gonococcus ordinarily begins its invasion of a new host by multiplying on the surface of a mucous membrane, i.e., an epithelial structure coated by a film of mucus. It seemed possible, therefore, that mucus, preferably human mucus, might furnish a suitable environment for the initiation of growth within the peritoneal cavity of the mouse. The impracticability of obtaining sterile human mucus* forced us to attempt the isolation of mucin from saliva and from the gastro-intestinal mucosa from fresh autopsy material, but the yields proving insufficient for the needs of the investigation, a commercial preparation of hog's gastric mucin, was tried out. While this did not serve the purpose for which it was intended, it did prove to be highly satisfactory as a menstruum in which to inoculate mice with meningococcus, with which trial inoculations had been carried in parallel. This had been done