Lacombe Research and Development Centre, Agriculture and Agri-Food Canada, Lacombe, AB, Canada.
Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.
Microbiome. 2019 Jun 5;7(1):86. doi: 10.1186/s40168-019-0696-4.
Beef cattle in North America frequently receive an antibiotic injection after feedlot placement to control and manage bovine respiratory disease. The potential collateral effect of these antibiotics on the bovine microbiome is largely unknown. Therefore, we determined the longitudinal impact of two commonly administered veterinary antibiotics, oxytetracycline and tulathromycin, on the fecal and nasopharyngeal (NP) microbiota of beef cattle that were transported to a feedlot. We also report the effect these antibiotics have on several antibiotic resistance determinants in both the fecal and NP microbiome.
Oxytetracycline and tulathromycin perturbation of the bovine fecal and NP microbiota was greatest at days 2 and 5. Although the NP microbiota of the tulathromycin-treated cattle had recovered by day 12, the NP microbiota of the oxytetracycline-treated group remained altered through day 34. Overall, the NP microbiota appeared to be more sensitive to antibiotic treatment than the fecal microbiota. Members of the bacterial Microbacteriaceae family were most notably affected by antibiotic administration in the NP microbiota. Both antibiotics protected against Pasteurella spp. in the nasopharynx at days 2 and 5. Despite very similar diets at both locations, the largest shift in the fecal and NP microbiota occurred after transport to the feedlot (P < 0.05). Antibiotic resistance determinants in the NP microbiome were also affected more strongly by antibiotic treatment than those in the fecal microbiome. Oxytetracycline increased the proportion of erm(X), sul2, tet(H), tet(M), and tet(W) in NP samples and tet(M) and tet(W) in fecal samples, at day 12 (P < 0.05). The effect of tulathromycin on the relative abundance of resistance genes in the NP microbiome was greatest at day 34 as erm(X), sul2, and tet(M) were enriched (P < 0.05).
Administration of a single injection of oxytetracycline and tulathromycin resulted in significant changes in the NP and fecal microbiota during the first 5 days after treatment. Antibiotic treatment also increased the relative abundance of several antibiotic resistance determinants in the fecal and NP microbiome at either day 12 or 34.
北美的肉牛在进入饲养场后通常会接受抗生素注射，以控制和管理牛呼吸道疾病。这些抗生素对牛微生物组的潜在附带影响在很大程度上是未知的。因此，我们确定了两种常用兽医抗生素，土霉素和替米考星，对运输到饲养场的肉牛的粪便和鼻咽（NP）微生物组的纵向影响。我们还报告了这些抗生素对粪便和 NP 微生物组中几种抗生素抗性决定因素的影响。
土霉素和替米考星对肉牛粪便和 NP 微生物组的扰动在第 2 天和第 5 天最大。尽管替米考星治疗的牛的 NP 微生物组在第 12 天已经恢复，但接受土霉素治疗的牛的 NP 微生物组在第 34 天仍保持改变。总体而言，NP 微生物组似乎比粪便微生物组对抗生素治疗更敏感。NP 微生物组中细菌微杆菌科的成员受抗生素给药的影响最为明显。两种抗生素在第 2 天和第 5 天都能预防鼻咽部巴氏杆菌属的感染。尽管在两个地点的饮食非常相似，但在运输到饲养场后，粪便和 NP 微生物组发生了最大的变化（P<0.05）。NP 微生物组中的抗生素抗性决定因素也比粪便微生物组更容易受到抗生素治疗的影响。土霉素在第 12 天增加了 NP 样本中的 erm(X)、sul2、tet(H)、tet(M)和 tet(W)以及粪便样本中的 tet(M)和 tet(W)的比例（P<0.05）。替米考星对 NP 微生物组中抗性基因相对丰度的影响在第 34 天最大，erm(X)、sul2 和 tet(M)被富集（P<0.05）。
单次注射土霉素和替米考星后，在治疗后第 5 天内，NP 和粪便微生物组发生了显著变化。抗生素治疗还增加了粪便和 NP 微生物组中几种抗生素抗性决定因素的相对丰度，无论是在第 12 天还是第 34 天。
