Genetic characterization of CTX-M-55-producing <i>Escherichia coli</i> isolated from commercial farms by integrated broiler chicken operations in Korea
Bibliographic record
Abstract
Recently, the occurrence of β-lactamase CTX-M-55-harboring Escherichia coli has been rapidly increasing in poultry worldwide, including Korea. In this study, three CTX-M variants were identified within 466 β-lactam-resistant E. coli isolated from fecal and dust samples of 74 commercial farms, with CTX-M-55 (28.4%) having the highest prevalence in all operations. Among the 28 CTX-M-55-producing E. coli isolates, ST3285 (28.6%) and group B1 (60.7%) were the most prevalent sequence type (ST) and phylogenetic group, respectively. All CTX-M-55 producing E. coli isolates were resistant to ampicillin, and showed very high minimum inhibitory concentrations of ≥512 to cefazolin, the first-generation cephalosporins, and to cefotaxime and ceftiofur, which are third-generation cephalosporins, respectively. Moreover, 27 (96.4%) CTX-M-55-producing E. coli isolates showed multidrug resistance against four or more antimicrobial classes. The most common plasmid replicon type was the combination of FII and FIB (67.9%). Also, 10 (35.7%) CTX-M-55-producing E. coli isolates harbored other β-lactamase genes simultaneously, and 12 (42.9%) isolates were identified as avian pathogenic E. coli. This study suggests that comprehensive surveillance and continuous monitoring are necessary to prevent the spread of CTX-M-55-producing E. coli in the poultry industry , which poses a threat to public health.
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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 | 0.001 |
| 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 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".