Studies with Shigella Dysenteriae (Shiga)

Abstract

Summary Shiga toxin, when given parenterally, is a potent and fatal poison for monkeys, but is completely innocuous when in contact with the normal intestinal mucosa. An attempt was made to produce clinical symptoms of bacillary dysentery in 4 Macaca mulatta monkeys by introducing Shigella dysenteriae (Shiga) toxin into an isolated portion of the intestine devoid of gastric juice, bile and pancreatic juice, and under conditions where the introduced toxin was not removed by peristalsis or leakage. In one experiment the isolated bowel treated with lysozyme was injected with living cultures of S. dysenteriae (Shiga). No symptoms of illness occurred in any of the monkeys but antitoxin and precipitins to Shiga toxin developed in the serum of monkeys following the introduction of toxin into the pouches, and protected them against otherwise fatal parenteral injections of toxin. Toxin could not be demonstrated in pouch washings on the day following its injection into the pouches. Experiments with similar pouches, excised and suspended in a saline bath, indicated that detoxification takes place in the pouch before absorption. There was some evidence that it might be excreted in nontoxic form in the feces. The aerobic Gram-negative flora of the pouches is reported. Although this study has not elucidated the role of the neurotoxin in Shiga infections, some interesting observations concerning the toxin have been brought to light.