On the isolation of streptococci from rabbits

Abstract

In our work for the purpose of investigating the relation of streptococci to poliomyelitis as claimed by Dr. E. C. Rosenow, we have made cultures of the brains of 6 monkeys and 20 rabbits. Our technique was as follows:

The animals were etherized just before death and, when anesthetized, were fastened to an autopsy-board—abdomen downward. With animals that died during the night this part of the procedure could not, of course, be carried out. Our purpose was to make sure, whenever possible, that any organisms cultivated from the brains were not post-mortem invaders, but were present during the life of the animal. A median incision was made through the skin over the skull running from the tip of the nose to the back of the neck, and the skin dissected back on both sides of the head. The skull was disinfected with tincture of iodine, and the head and body covered with 3 layers of gauze soaked in lysol. A small hole was made in the gauze so as to expose the upper part of the skull. The skull was next opened, and, to further insure sterility, the surface of the brain was seared with a scalpel. A big piece, and sometimes one-half of the brain was removed with a pair of long forceps and then immediately put into a Rosenow sterile air chamber, where it was emulsified. (The chamber was sterilized in the hot-air sterilizer for one hour at 160° C.) In some cases it was possible to remove considerable parts of the brain while the animal was still alive. The emulsion was poured into a large tube from which different media were inoculated with sterile pipettes. The tubes were examined after two days and, if they were found to be sterile, were again examined two or three days later.