Department of Veterinary Medicine and Surgery, University of Missouri, Columbia 65211.
Department of Veterinary Pathobiology, University of Missouri, Columbia 65211.
J Dairy Sci. 2020 Apr;103(4):3459-3469. doi: 10.3168/jds.2019-17554. Epub 2020 Feb 7.
The purpose of this study was to determine the effect of intramammary pirlimycin on the fecal microbiome of dairy cattle. Primiparous heifers were enrolled and assigned to a treatment or control group at a ratio of 2:1. In part 1 of the study, treated heifers (T1) were given intramammary pirlimycin into one infected quarter once daily for 2 d at 24-h intervals, according to the label instructions. Control heifers received no treatment. In part 2 of the study, treated heifers (T2) were given intramammary pirlimycin into one infected quarter once daily for 8 d at 24-h intervals, according to the label instructions. All enrolled heifers (T1, T2, and control) had quarter-level milk samples aseptically collected for bacterial culture and fecal samples collected for 16S rRNA gene sequencing on d 0, 2, 7, 14, 21, and 28. Milk samples were plated on Columbia blood agar and incubated at 37°C for 24 h. Bacteria were identified using MALDI-TOF mass spectrometry. The DNA was extracted from feces using PowerFecal kits (Qiagen, Venlo, the Netherlands). The 16S rRNA gene amplicon library construction and sequencing was performed at the University of Missouri DNA Core facility. Testing for differences in fecal community composition was performed via one-way permutational multivariate ANOVA of Bray-Curtis and Jaccard similarities using Past 3.13 (https://folk.uio.no/ohammer/past/). Mean total count of operational taxonomic units and Chao1, Shannon, and Simpson α-diversity indices were determined and compared via t-test or Wilcoxon rank sum test. A treatment-dependent effect was present in the observed and predicted richness of feces from cows in the T1 group at d 2 posttreatment. Additionally, intramammary pirlimycin induced a significant change in the composition of the fecal microbiota by d 2 in the treated groups. Based on calculated intra-subject similarities, intramammary pirlimycin was associated with a significant acute change in the fecal microbiota of dairy heifers and that chance reversed when the antimicrobial exposure was brief, but sustained following longer exposure. Overall, intramammary pirlimycin administration affected the fecal microbiome of lactating dairy heifers. Further work is necessary to determine the effect of these changes on the heifer and the dairy environment as well as if treatment is influencing antimicrobial resistance among enteric and environmental bacteria.
本研究旨在确定皮利霉素的局部应用对奶牛粪便微生物群的影响。选择初产奶牛，并按照 2:1 的比例将其随机分配至治疗组或对照组。在研究的第一部分，按照标签说明，治疗组奶牛（T1）于 24 小时间隔内，每天对 1 个患病乳区单次注射皮利霉素，连续 2 天。对照组奶牛不接受任何治疗。在研究的第二部分，治疗组奶牛（T2）按照标签说明，于 24 小时间隔内，每天对 1 个患病乳区单次注射皮利霉素，连续 8 天。所有入组奶牛（T1、T2 和对照组）均在第 0、2、7、14、21 和 28 天无菌采集乳区奶样进行细菌培养，并采集粪便样进行 16S rRNA 基因测序。将牛奶样本接种于哥伦比亚血琼脂平板，并在 37°C 孵育 24 小时。使用基质辅助激光解吸电离飞行时间质谱法（MALDI-TOF MS）鉴定细菌。使用 PowerFecal 试剂盒（Qiagen，荷兰 Venlo）从粪便中提取 DNA。16S rRNA 基因扩增子文库构建和测序在密苏里大学 DNA 核心设施进行。通过 Past 3.13（https://folk.uio.no/ohammer/past/）对粪便群落组成的差异进行检测，采用单向排列多变量方差分析（PERMANOVA）比较布赖恩-柯蒂斯（Bray-Curtis）和雅可比（Jaccard）相似性。通过 t 检验或 Wilcoxon 秩和检验确定并比较处理组和对照组粪便的总操作分类单元（OTU）计数和 Chao1、香农和辛普森α多样性指数。结果显示，T1 组奶牛在治疗后第 2 天的粪便观察和预测丰度出现了治疗依赖性效应。此外，在治疗组中，皮利霉素在第 2 天就显著改变了粪便微生物群的组成。基于个体内相似性的计算，皮利霉素与奶牛粪便微生物群的急性变化显著相关，当抗生素暴露时间短暂但持续时间较长时，这种变化趋势会逆转。总体而言，皮利霉素的局部应用影响了泌乳奶牛的粪便微生物群。需要进一步研究以确定这些变化对奶牛和奶牛养殖环境的影响，以及治疗是否会影响肠道和环境细菌的抗生素耐药性。
