摘要

       美国牛肉生产中减少抗菌素 (AM) 使用可预期的特定抗菌素耐药性 (AMR) 下降尚未确定。为了弥补这一数据差距，我们从 36 头“无抗生素饲养”（RWA）和 36 头“常规”（CONV）肉牛中回收了粪便。样品 (n = 719) 在收获期间收集并分发了一年。 AMR 的评估方法包括 (i) 6 种抗 AM 细菌 (ARB) 的培养，(ii) 10 个 AMR 基因 (ARG) 的定量 PCR (qPCR)，(iii) 84 个 ARG 的 qPCR 阵列，以及 (iv) 宏基因组学测序。一般来说，AMR 水平相似，但 CONV 肉牛的 AMR 水平更高。第三代头孢菌素耐药 (3GCr) 大肠杆菌的流行率在生产系统之间略有不同（CONV，47.5%；RWA，34.8%；P = 0.04），但季节性影响（夏季，92.8%；冬季，48.3%） ; P < 0.01) 更大。耐红霉素 (ERYr) 肠球菌属。生产系统之间的浓度显着不同（CONV，1.91 log10 CFU/g；RWA，0.73 log10 CFU/g；P < 0.01）。 aadA1、ant(6)-I、blaACI、erm(A)、erm(B)、erm(C)、erm(F)、erm(Q)、tet(A)、tet(B)、tet( M) 和 tet(X) ARG 在 CONV 系统中更高（P < 0.05）。通过宏基因组测序检测到的所有 43 个 ARG 的总丰度以及氨基糖苷类、β-内酰胺、大环内酯-林可酰胺-链霉素 B (MLS) 和四环素 AM 类别中 ARG 的总丰度在 CONV 之间没有差异（log2 倍变化 < 1.0）和 RWA 系统。这些结果表明，在美国肉牛生产中进一步减少 AM 使用可能不会产生显着的 AMR 降低，超出 MLS 和四环素抗性。

       The anticipated decline in specific antimicrobial resistance (AMR) from the reduction of antimicrobial (AM) use in US beef production has not yet been determined. To bridge this gap in data, we recovered feces from 36 “antibiotic-free feeding” (RWA) and 36 “conventional” (CONV) beef cattle. The samples (n = 719) were collected and distributed for one year during the harvest. AMR evaluation methods include (i) 6 kinds of anti-AM bacteria (ARB) culture, (ii) quantitative PCR (qPCR) of 10 AMR genes (ARG), (iii) qPCR array of 84 ARGs, and (iv) Metagenomics sequencing. Generally speaking, AMR levels are similar, but CONV beef cattle have higher AMR levels. The prevalence of third-generation cephalosporin-resistant (3GCr) Escherichia coli varies slightly between production systems (CONV, 47.5%; RWA, 34.8%; P = 0.04), but seasonal effects (in summer, 92.8%; In winter, 48.3%); P <0.01) is greater. Erythromycin-resistant (ERYr) Enterococcus spp. The concentration varies significantly between production systems (CONV, 1.91 log10 CFU/g; RWA, 0.73 log10 CFU/g; P <0.01). aadA1, ant(6)-I, blaACI, erm(A), erm(B), erm(C), erm(F), erm(Q), tet(A), tet(B), tet( M) And tet(X) ARG is higher in the CONV system (P <0.05). The total abundance of all 43 ARGs detected by metagenomic sequencing and the total abundance of ARGs in the aminoglycoside, β-lactam, macrolide-lincosamide-streptomycin B (MLS) and tetracycline AM categories There is no difference in degree between CONV (log2 times change <1.0) and RWA system. These results indicate that further reductions in AM use in US beef cattle production may not produce a significant reduction in AMR beyond MLS and tetracycline resistance.

https://journals.asm.org/doi/full/10.1128/AEM.01682-17