Studies on the pathogenicity of Pseudomonas aeruginosa by the use of ligated rabbit intestines (the De test).

The De test was used as a test to assess the pathogenicity of Pseudomonas aeruginosa in vivo. The test was positive in rabbits inoculated intraintestinally with the protease and elastase-producing strain IFO 3455 of P. aeruginosa whereas it was negative in those inoculated with the nonproducing strains NC-5 or PA103. Animals similarly injected with not less than 2.0 mg of protease or elastase showed positive De tests. The intestinal lesions produced in the animals with positive reaction to the inoculation with the enzyme-producing strain IFO 3455 was histopathologically characterized by atrophy, detachment and flattening of the mucosa with submucosal hemorrhage and atrophy of the Auerbach's plexus, which were nearly comparable to a sum of the microscopic findings found in the animals inoculated with respective enzymes singly. Namely, villi were noted to be atrophic and hemorrhage from the submucosal blood vessels was prominent with atrophy of the mesenteric plexus in the rabbits inoculated with protease alone, whereas in those injected with elastase alone, submucosal hemorrhage was less prominent besides the atrophy of the villi and mesenteric plexuses were markedly atrophic. These experimental findings are considered to suggest that the two enzymes liberated from P. aeruginosa, protease and elastase, may be implicated in the pathogenesis of P. aeruginosa enteritis.