小牛的育肥通常与高抗菌药物使用和抗微生物药物耐药性(AMR)的选择有关。这项纵向观测研究的目的是描述AMR和应变动力学,使用全基因组测序(WGS),22头小牛的粪便大肠杆菌。所有小牛在第(D)1天接受抗菌组治疗(土霉素,肌肉内)和D4至D12(多西环素,in-feed)。此外,八头小牛在D7和D59之间接受了单独的肠胃外治疗,包括氟苯尼考,阿莫西林,马波沙星,和加米霉素.在D1(治疗前)从所有小牛收集直肠拭子,D2、D9和D82。将拭子涂在肠杆菌选择性琼脂上,对每个平板的三个大肠杆菌菌落进行WGS。在所有小牛和采样时间的264个分离株中,确定了80个独特的菌株,其中大多数含有赋予四环素抗性的基因,链霉素,和磺胺类药物.在小牛的饲料中抗微生物组处理期间,菌株的多样性降低。在D82,90%的分离株是在以前的采样时间未分离的菌株,和四环素的AMR决定簇的每个菌株的中位数,氟苯尼考,β-内酰胺,喹诺酮类药物,或大环内酯类与D9相比减少。此外,一些菌株的克隆传播代表了AMR决定簇的主要传播途径。在这项研究中,WGS揭示了经过群体抗微生物处理的小牛粪便大肠杆菌的菌株多样性和基因型AMR随时间的重要变化。
目的:抗生素耐药性(AMR)决定因素的持续出现和传播是全球严重关注的问题。细菌和动物宿主种群中AMR传播和持久性的动态是复杂的,而不仅仅是由抗微生物选择压力驱动的。在小牛育肥中,抗菌药物的使用和耐药细菌的携带患病率通常被认为很高.这项研究提供了对短期的新见解,在饲养期间,经过抗菌组处理的小牛的优势粪便菌群的大肠杆菌中AMR决定簇的农场内动态和传播。大肠杆菌菌株的多样性随着时间的推移而下降,虽然,与以前在产超广谱β-内酰胺酶肠杆菌中的观察结果相反,没有观察到少数克隆的优势。AMR决定簇的传播是通过克隆菌株在小牛中的传播而发生的。在饲养期结束时,赋予对所选抗菌药物抗性的AMR决定簇的每个菌株的中位数减少。
The fattening of calves is often associated with high antimicrobial use and the selection of antimicrobial resistance (AMR). The objective of this observational longitudinal study was to describe the AMR and strain dynamics, using whole-genome sequencing (WGS), of fecal Escherichia coli in a cohort of 22 calves. All calves received antimicrobial group treatments on Day (D) 1 (oxytetracycline, intramuscularly) and on D4 through D12 (doxycycline, in-feed). Additionally, eight calves received individual parenteral treatments between D7 and D59, including florfenicol, amoxicillin, marbofloxacin, and gamithromycin. Rectal swabs were collected from all calves on D1 (prior to treatment), D2, D9, and D82. The swabs were spread onto Enterobacterales-selective agar, and three E. coli colonies per plate were subjected to WGS. Out of 264 isolates across all calves and sampling times, 80 unique strains were identified, a majority of which harbored genes conferring resistance to tetracyclines, streptomycin, and sulfonamides. The diversity of strains decreased during the in-feed antimicrobial group treatment of the calves. On D82, 90% of isolates were strains that were not isolated at previous sampling times, and the median number per strain of AMR determinants to tetracyclines, florfenicol, β-lactams, quinolones, or macrolides decreased compared to D9. Additionally, clonal dissemination of some strains represented the main transmission route of AMR determinants. In this study, WGS revealed important variations in strain diversity and genotypic AMR of fecal E. coli over time in calves subjected to group antimicrobial treatments.
OBJECTIVE: The continued emergence and spread of antimicrobial resistance (AMR) determinants are serious global concerns. The dynamics of AMR spread and persistence in bacterial and animal host populations are complex and not solely driven by antimicrobial selection pressure. In calf fattening, both antimicrobial use and carriage prevalence of antimicrobial-resistant bacteria are generally recognized as high. This study provides new insights into the short-term, within-farm dynamics and transmission of AMR determinants in Escherichia coli from the dominant fecal flora of calves subjected to antimicrobial group treatments during the rearing period. The diversity of E. coli strains decreased over time, although, in contrast to previous observations in extended-spectrum β-lactamase-producing Enterobacterales, the predominance of a few clones was not observed. The spread of AMR determinants occurred through the dissemination of clonal strains among calves. The median number per strain of AMR determinants conferring resistance to selected antimicrobials decreased toward the end of the rearing period.