Characterization of a Shiga Toxin-, Intimin-, and Enterotoxin Hemolysin-Producing <i>Escherichia coli</i> ONT:H25 Strain Commonly Isolated from Healthy Cattle
Bibliographic record
Abstract
Among bovine fecal and recto-anal mucosal swab samples cultured in our laboratory for Escherichia coli O157:H7, we frequently isolated E. coli organisms that were phenotypically similar to the O157:H7 serotype as non-sorbitol fermenting and negative for beta-glucuronidase activity but serotyped O nontypeable:H25 (ONT:H25). This study determined the prevalence and virulence properties of the E. coli ONT:H25 isolates. Among dairy and feedlot cattle (n = 170) sampled in Washington, Idaho, and Alberta, Canada, the percentage of animals culture positive for E. coli ONT:H25 ranged from 7.5% to 22.5%, compared to the prevalence of E. coli O157:H7 that ranged from 0% to 15%. A longitudinal 8-month study of dairy heifers (n = 40) showed that 0 to 15% of the heifers were culture positive for E. coli O157:H7, while 15 to 22.5% of the animals were culture positive for E. coli ONT:H25. As determined by a multiplex PCR, the E. coli ONT:H25 isolates carried a combination of virulence genes characteristic of the enterohemorrhagic E. coli, including intimin, translocated intimin receptor, Stx2, and hemolysin (eae-beta, tir, stx(2vh-a), and hly). E. coli ONT:H25 isolates from diverse geographic locations and over time were fingerprinted by separating XbaI-restricted chromosomal DNA by pulsed-field gel electrophoresis (PFGE) separation. Two strains of E. coli ONT:H25 were highly similar by PFGE pattern. Experimental inoculation of cattle showed that E. coli ONT:H25, like E. coli O157:H7, colonized the bovine recto-anal junction mucosa for more than 4 weeks following a single rectal application of bacteria.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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 source (direct Gemma or distilled Codex), 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".