Antimicrobial use and resistance in Canadian cow-calf herds
Notice bibliographique
Résumé
Antimicrobial resistance (AMR) is a concern to human health and has been a growing concern for the public and livestock producers in recent years. The existing literature regarding antimicrobial use (AMU) and AMR in cow-calf herds, a critical component of the beef supply chain, is limited and much of it is more than a decade old. The goal of this thesis is to address the existing gaps by examining AMU practices on Canadian cow-calf operations and AMR in two enteric species important to human health: E. coli and Enterococcus.\nIn Chapter 2, a survey was used to collect AMU data from herds across the country. AMU data for the period of July 1, 2019, to June 30, 2020, was collected from 146 herds. Ninety-nine percent (145/146) reported the use of an antimicrobial at least once during the study period; however, frequency of use within herds was low. The antimicrobial most likely to be reported as used by participating herds was oxytetracycline (81%, 118/146). Category I antimicrobials were used at least once by 33% (48/146) of herds, with no herds reporting treatment of more than 30% of animals with a Category I antimicrobial. Factors such as calving season and herd type were shown to influence AMU practices. Overall, AMU practices were similar to previous studies examining AMU in cow-calf herds.\nIn Chapter 3, AMR patterns in fecal E. coli were examined in samples collected from cows and calves in the spring and fall of 2021 from western Canadian herds. In total, 1,551 E. coli isolates were obtained from 809 calves and 746 cows, resulting in an isolation rate of 99.7%. AMR susceptibility testing was completed using the NARMS panel for gram-negative bacteria. Overall, 15% (231/1551) of the recovered isolates were resistant to a single antimicrobial. Resistance was found at least once in nearly every herd (90%, 35/39). Resistance of E. coli to Category I antimicrobials was very infrequent, with tetracycline being the most common resistance target. Calves were more likely to display resistance than cows, with a higher proportion of calves also displaying multiclass resistance. Additionally, calves in the spring were more likely to display resistance compared to calves in the fall.\nIn the fourth chapter, antimicrobial resistance patterns were described for Enterococcus. Enterococcus has not previously been studied in Canadian cow-calf herds. Recovery rates for Enterococcus were good (97%), with 1,505 isolates recovered from 1,555 animals consisting of 809 calves and 746 cows. Resistance of isolates to at least one antimicrobial was 98% in the spring and 96% in the fall. The antimicrobials of quinupristin/dalfopristin and tetracycline were common resistance targets in both cows and calves. When summarized at the herd level, multiclass resistance and resistance to Category I antimicrobials was greater in calves than in cows. AMR resistance in Enterococcus is complicated by questions regarding the role of intrinsic resistance in observed susceptibility data. There are also concerns that current minimum inhibitory concentration (MIC) breakpoints are not accurate for all Enterococcal species further complicating the interpretation of the study findings. Future studies will be required to better understand the prevalence of resistance amongst different bacteria of interest in cow-calf herds.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,003 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».