Prevalence of <i>Escherichia coli</i> O157:H7 in Gut Contents of Beef Cattle at Slaughter
Bibliographic record
Abstract
Fecal shedding of Escherichia coli O157:H7 in cattle, except those that shed transiently, is due to the organism's ability to persist in the gut. Site of prevalence in the gut is important for understanding the mechanisms and factors affecting gut persistence and fecal shedding and is a potential target for intervention. The prevalence of E. coli O157:H7 in the rumen, cecum, colon, and rectum was determined with contents collected from slaughtered cattle (n = 815) at an abattoir. Isolation and identification of E. coli O157:H7 were by selective enrichment, immunomagnetic separation, plating on selective medium, agglutination for O157 antigen, and presence of virulence genes. Prevalence in the rumen, cecum, colon, and rectum was 4.9%, 9.9%, 7.6%, and 11.1%, respectively. The overall prevalence of E. coli O157:H7 in the cattle sampled, based on being positive in any one gut location, was 20.3%. E. coli O157:H7 in rectal contents was positively associated (p < 0.01) with presence in the rumen or colon but not in the cecum. Pulsed-field gel electrophoresis (PFGE) was performed to compare the clonal similarity of isolates (n = 144) obtained from the rectum with that of rumen, cecum, or colon within cattle (n = 77). The majority (79-90%) of isolates obtained within the same animal shared a common PFGE type. There were no significant differences in PFGE type between positive samples from the rectum and samples from other locations within the same animal. Acid tolerance for cattle with positive rumen (pregastric) isolates and with at least one other positive hindgut (postgastric) isolate within the same animal was determined. There was no significant difference between gut locations in log reduction following acid challenge. The hindgut was the major site of prevalence of E. coli O157:H7 in cattle, a majority of the isolates within the same animal were clonally similar, and acid tolerance of hindgut isolates were not different from that of ruminal isolates.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".