Prevalence and molecular characterization of clostridium difficile in veal calves and feedlot beef cattle
Bibliographic record
Abstract
This research addressed for the first time the prevalence of ' Clostridium difficile' in a veal calf production unit and in feedlot beef cattle using a longitudinal design. For the veal farm study, rectal swabs were collected from 183 calves at arrival, as well as 1, 17 and 21 weeks later. Selective culture for ' C. difficile' was performed and the isolates recovered were characterized by PCR ribotyping, PCR for 'tcdA, tcdB, cdtA' and ' tet'(M) and E-test for tetracycline susceptibility. Overall, ' C. difficile' was isolated from 32% (56/174), 51% (88/172), 2% (4/183) and 2% (4/156) calves during successive samplings. Calves were two times more likely to test positive during the second sampling compared to the first sampling. The number of calves shedding 'C. difficile' was significantly lower after second sampling. Twelve different ribotypes were present at the first time point, and only three ribotypes at the second sampling. Ribotype 078 was the most common strain found. Close to 99% of the toxigenic strains isolated in the study have been identified in humans. There was a significant increase in tetracycline resistant isolates and in the number of bacteria carrying the 'tet'(M) gene. For the second study, four commercial feedlots in Alberta, Canada were enrolled. Fecal samples were collected at the time of arrival and shipping. Selective culture for 'C. difficile' was performed, and isolates were characterized by ribotyping and pulsed-field gel electrophoresis. A total of 543 cattle were enrolled. 'Clostridium difficile' was isolated from 3.3% of cattle at the time of arrival and from 5.5% at the time of shipping. Overall, there was no difference in the prevalence of ' C. difficile' shedding, however, on one of the farms, prevalence was higher at shipping. When only paired samples were evaluated, there was a significant difference in prevalence between arrival and exit in one of the four feedlots, as well as overall, with 'C. difficile' isolated from 2.1% at arrival and 5.5% at exit. All the isolates recovered were ribotype 078, a toxinotype V strain with genes encoding toxins A, B and CDT. In addition, all strains were classified as NAP7 by PFGE.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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".