Studies on anthrax infection

Abstract

The unsettled problems of infection with B. anthracis are very many. Besredka has recently declared his belief that the cutaneous is the only route of infection. Intestinal anthrax is the commonest form in which the natural disease appears to be found. The question has been raised whether there is such an infection. The opposing view is that the findings and symptoms in the intestines are only part of a general infection and that the portal of entry is in the skin, usually about the mouth and nose, and the local reaction, if any, is overlooked. In carrying out some experiments to cover some of the doubtful points we undertook the feeding of guinea pigs, taking particular care not to contaminate the mouth cavity. The technic used by previous workers did not seem satisfactory so a simple method was tried which protected against these possible contaminations. Small gelatine capsules were filled with the culture to be used, the mouth was opened and the capsules placed in the back of the throat. The animal swallowed them promptly. A guinea pig was fed in this way with a virulent culture rich in spores and a daily culture of the feces was made in agar after heating to 75°C for 15 minutes. A fecal pellet was emulsified in 10 c.c. of saline and 1 c.c. was used for the plate. The colony characteristic of B. anthracis is easily recognized but isolations were made each day and tested on fresh animals. In this way we found virulent anthrax spores in the feces up to the seventh day. Two weeks after the feeding the animal was given a subcutaneous dose and died of anthrax. A second pig was fed in the same way and positive fecal cultures were obtained up to the fifth day.