Perineal swabs reveal effect of super shedders on the transmission of Escherichia coli O157:H7 in commercial feedlots1
Bibliographic record
Abstract
Cattle that shed more than 10(4) cfu/g of Escherichia coli O157 in feces have been described as super shedders (SS) and are thought to have major impacts on prevalence and transmission of this organism. Two Southern Alberta commercial feedlots (feedlot X, 7 pens averaging 183 steers; feedlot Y, 5 pens averaging 153 steers) were sampled from May 2007 to January 2008. Background samples [fecal pat (FP) water, ropes] were taken weekly from each pen for 2 wk before collection of samples from individuals [fecal grab (FG); perineal swab] at 2 different times [during spring and summer (S1); immediately before slaughter during fall and winter (S2)]. Immunomagnetic separation and selective media were used for detecting E. coli O157:H7. Positive FG and FP were enumerated by direct plating onto sorbitol MacConkey agar supplemented with 2.5 mg/L of potassium tellurite and 0.05 mg/L of cefixime. Five sorbitol-negative colonies were agglutinated using an anti-O157 latex kit, and the proportion of positive colonies was adjusted for non-E. coli O157:H7. Overall, there were 153 (7.16%) and 10 (0.45%) SS at S1 and S2, respectively. In feedlot X, SS and penmates of SS during S1 were more likely (P < 0.01) to shed E. coli O157:H7 in their feces and have this organism on their perineum than cattle in a pen where no SS were identified. In feedlot Y, SS and penmates of SS during S1 were more likely (P < 0.01) to have E. coli O157:H7 on their perineum than those from a pen where only 1 SS was identified, but steers in only 1 pen with multiple SS were more likely (P < 0.01) to shed this organism in feces. Overall, E. coli O157:H7 was 1.85 times more likely (P < 0.01) to be detected in perineal swabs compared with FG and E. coli O157:H7 was more likely (P < 0.01) to be detected at S1 compared with S2 for all sample types. Super shedders were a larger proportion of shedding cattle in S1 than in S2, but the presence of SS increased (P < 0.01) prevalence of this organism on the perineum of cattle throughout the year. Even when SS did not increase fecal shedding of E. coli O157:H7, their presence increased contamination of hides, an outcome that could have important implications for contamination of carcasses at the abattoir.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 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) | 0.001 | 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".