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Enteropathogenicity of Escherichia coli. I. Evaluation of mouse intestinal loops
Abstract:
A ligated mouse intestinal loop assay has been introduced to evaluate the enteropathogenicity of strains of Escherichia coli. When inoculated as whole cultures, 19 (34%) of 55 strains isolated from diarrheic infants, each of 4 strains associated with diarrhea in human adults, and 5 of 7 strains associated with porcine coli bacillosis were found capable of causing fluid accumulation in this model. In contrast, only 1 of 28 strains isolated from normal individuals was positive in this test. Sterile concentrated filtrates of positive strains cultivated in Brain Heart Infusion broth or syncase broth were also positive, whereas filtrates of negative strains did not cause fluid accumulation. All of the strains associated with diarrhea in human adults and 16 of the 19 positive strains from diarrheic children were also found capable of causing hemagglutination of chicken erythrocytes in a slide test used to evaluate the "adhesiveness" of the bacteria, a property which may enable them to stick in the small bowel and avoid the normally efficient peristaltic clearance mechanism. Few of the nonenteropathogenic strains were positive in this test. The slide hemagglutination test may be a useful, rapid means of screening potentially enteropathic E. coli strains and merits further evaluation and study. Although not ideal, the mouse intestinal loop model offers some advantages over the rabbit ileal loop assay.
Insights
A mouse intestinal loop assay effectively identifies enteropathogenic Escherichia coli (E. coli) strains from human and animal diarrheal cases. Hemagglutination tests also show promise for rapidly screening these disease-causing E. coli.
Area of Science:
- Microbiology
- Veterinary Medicine
- Gastroenterology
Background:
- Enteropathogenic Escherichia coli (E. coli) are a significant cause of diarrheal disease in humans and animals.
- Accurate identification of pathogenic E. coli strains is crucial for effective treatment and control.
Purpose of the Study:
- To evaluate the efficacy of a ligated mouse intestinal loop assay for assessing E. coli enteropathogenicity.
- To investigate the correlation between fluid accumulation in the mouse model and bacterial hemagglutination properties.
Main Methods:
- A ligated mouse intestinal loop assay was used to test E. coli strains from various sources.
- Sterile filtrates of bacterial cultures were also tested for fluid accumulation.
- A slide hemagglutination test using chicken erythrocytes assessed bacterial adhesiveness.
Main Results:
- 34% of E. coli strains from diarrheic infants, all strains from adult diarrhea, and 5/7 from porcine coli bacillosis caused fluid accumulation.
- Only 1/28 strains from normal individuals were positive in the loop assay.
- Positive strains in the loop assay, particularly those from human diarrhea, exhibited hemagglutination.
Conclusions:
- The mouse intestinal loop assay is a viable model for evaluating E. coli enteropathogenicity.
- Bacterial hemagglutination may serve as a rapid screening method for potentially enteropathogenic E. coli.
- The mouse model offers advantages over existing rabbit ileal loop assays.