Germination of B. anthracis spores in the peritoneal cavity of rats and establishment of anthrax.

Abstract

ABSTRACTMost of spores of B. anthracis introduced into the peritoneal cavity of rats could germinate when 5 mg of L‐alanine and 5 mg of adenosine were injected by the same route shortly before the spore injection. However the spores hardly germinated in untreated rats. To develop vegetative cells after spore germination, 1 ml of an aqueous solution containing 1% casamino acid and 1% of yeast extract was injected into the peritoneal cavity of rats before injection of 55×107 spores of B. anthracis. A few germinated spores and vegetative cells were seen in ascites, but their numbers were not enough to kill the rats. In order to produce a rapid germination and development to vegetative cells in a short time, 1 ml of solution containing 1% of casamino acid, 1% of yeast extract, 5 mg of L‐alanine and 5 mg of adenosine was injected before intraperitoneal administration of spore suspension. Spore germination and vegetative growth were tremendous and all of rats died within 24 hours. From these results it was concluded that the natural resistance of the rat for B. anthracis is partly due to unfavorable internal conditions for spore germination and subsequent vegetative growth.