Experimental Paratyphoid Intoxication in Man.

Abstract

In a number of food poisoning outbreaks competent bacterial examination has failed to reveal the presence of any living microorganisms. It has been inferred especially by Savage and White 1 that many of the outbreaks were due to poisonous thermostabile growth products of B. aertrycke or B. enteritidis. Animal experimentation along this line has not met with uniform success since most workers have been unable to reproduce symptoms of paratyphoid intoxication by feeding the sterile products of B. aertrycke or B. enteritidis to animals.

In our experiments 24 people, ranging in ages from 20 to 40 were fed heat killed cultures or filtrates of B. aertrycke and B. enteritidis. Nine strains were used, 5 of B. aertrycke and 4 of B. enteritidis. The date of isolation and colony morphology of these strains are as follows:

The cultures were grown in beef heart medium containing 1% of dextrose. They were incubated at 37° C. for periods varying from 2 hours to 20 days. After incubation the supernatant fluid from each culture was divided and half was filtered through a Mandler filter and the remaining half was boiled for 20 minutes. Before feeding both the heat killed cultures and filtrates were tested for sterility. Rabbits were given intravenous injections of the heat killed cultures and filtrates in amounts ranging from 0.5 to 2.0 cc. All of the animals showed symptoms of dyspnea and many showed prostration and death. The filtrates from the 6 hour cultures were much more toxic than those from older cultures.