B. coli Bacteriophage in the Treatment of B. coli Peritonitis in Mice

Abstract

The bacteriophage which was used for this study was found to produce a complete lysis of 2 virulent strains of B. coli which we obtained from patients with peritonitis. One one hundred billionth of a cc. of this bacteriophage caused lysis of approximately one billion bacteria of strain “T” in 10 cc. of broth. The minimal lethal dose of the “T” strain of B. coli for mice at the time of the experiments was 1-5 million organisms which killed within 5 to 12 hours after injection of an actively growing, 3-hour, 2% dextrose cooked meat medium culture. Fifty million bacteria which constituted 10-50 M.L.D.'s were suspended in 0.5 cc. of broth and inoculated intraperitoneally into a series of mice. 0.5 cc. of bacteriophage was injected simultaneously into 2 of these mice, and into 2 more mice at varying intervals up to 4 1/2 hours after the bacterial inoculation. This approached closely the lethal period for control animals. In the control series plain broth injections were given at the same intervals as phage. The table shows one of these experiments. From this table one can see that 0.5 cc. of bacteriophage protected all of the mice when given up to 3 1/2 hours after bacterial inoculation. Only 50% of mice could be saved when bacteriophage was given after 4 hours. In similar experiments there was occasional recovery when phage was inoculated after 4 1/2 hours or later. Control animals receiving B. coli filtrate instead of phage were not saved. The bacteriophage itself proved to be innocuous, for 2 cc. and 4 cc. of it injected respectively into the peritoneal cavity of 2 mice did not produce any harmful effect. Both mice survived and the one inoculated with the larger dose suffered only slight discomfort for 1 or 2 hours, probably due to distention from the quantity of fluid injected.