Effect of ceftiofur cessation and substitution with lincomycin-spectinomycin on extended-spectrum-beta-lactamase/AmpC genes and multidrug resistance in <i>E. coli</i> from a Canadian broiler production pyramid
Bibliographic record
Abstract
Abstract Ceftiofur, a cephalosporin antimicrobial, was used systematically in Canadian hatcheries for many years to prevent early mortality in chicks leading to a high prevalence of cephalosporin resistance in Escherichia coli in chickens. Preventive use of ceftiofur in hatcheries ceased in 2014. We examined the effect of ceftiofur cessation and replacement with lincomycin-spectinomycin at the hatchery on the proportion of E. coli positive for extended-spectrum β-lactamase (ESBL) and AmpC β-lactamase related genes, and on the multidrug resistance profiles of ESBL/AmpC positive E. coli in broilers and their associated breeders, at one year post-cessation. For indicator E. coli from non-enriched media, a significant decrease post-cessation in the proportion of samples harboring E. coli isolates positive for bla CMY-2 and/or bla CTX-M was observed. In contrast, following enrichment in medium containing ceftriaxone (1mg/L) to facilitate recovery of ESBL/AmpC β-lactamase producing E. coli colonies, both pre- and post-cessation, 99% of the samples harbored E. coli positive for bla CMY-2 or bla CTX-M . Flocks receiving lincomycin-spectinomycin after cessation of ceftiofur showed a significantly greater non-susceptibility to aminoglycoside, folate inhibitor, phenicol, tetracycline and possible extensively drug resistant E. coli compared to those receiving ceftiofur or no antimicrobial at hatchery. This study clearly demonstrates an initial decrease in ESBL/AmpC positive E. coli following the cessation of ceftiofur in hatchery but an increase in multidrug resistant E. coli following replacement with lincomycin-spectinomycin. Importance Antimicrobial resistance is a global problem. The antimicrobial ceftiofur has been used worldwide for disease prevention in poultry production resulting in a greatly increased resistance to this antimicrobial important in poultry and human medicine. Our study examines the impact of ceftiofur cessation and its replacement with the antimicrobial combination lincomycin-spectinomycin, a common practice in the industry. Our study demonstrated a decrease in ceftiofur resistance after the cessation of its use, although the resistance genes remain ubiquitous in all phases of poultry production, showing that poultry remains a reservoir for ceftiofur resistance and requiring continued vigilance. We also observed a decrease in multidrug resistance after cessation of ceftiofur although the contrary finding following use of lincomycin-spectinomycin indicates that the use of these antimicrobials should be questioned. Reduced resistance to ceftiofur in poultry may translate to better treatment efficacy, decreased morbidity, mortality, duration and cost of hospitalization in humans.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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".