| Abstrakt: |
The enteropathogenicity of 6 strains of Escherichia coli was evaluated via the ligated loop technique in 15 gnotobiotic swine 3 to 4 weeks old. Strain enteropathogenicity in gnotobiotic swine, as determined on the basis of visual loop distention and light microscopic evaluation of intestinal sections, compared favorably with that reported in conventional swine, except that jejunal loops of gnotobiotic swine may be somewhat less sensitive to certain strains. In addition, postoperative mortality rate among gnotobiotic pigs was greater than that reported in conventional pigs. Two types of aberrant loop reactions were observed during the experiment. The 1st, and the more commonly encountered type, was due to the leakage of enteropathogenic organisms or enterotoxin from one loop to another; this was considered to be a true false-positive reaction. The 2nd type of unexpected positive reaction occurred in 2 sacs inoculated with the nonenteropathogenic strain 115. This latter reaction may have represented either a reversion of the organism to its previous enteropathogenic state or a unique reaction of the gnotobiotic intestine to this strain. False-positive loops were not identified in any other sacs, whether inoculated or not. Results of these experiments support the hypothesis that false-positive loops originate from naturally occurring infection. |
