Centeno-Martinez Ruth Eunice, Klopp Rebecca N, Koziol Jennifer, Boerman Jacquelyn P, Johnson Timothy A
Department of Animal Science, Purdue University, West Lafayette, IN, United States.
School of Veterinary Medicine, Texas Tech University, Amarillo, TX, United States.
Front Vet Sci. 2023 Nov 16;10:1297158. doi: 10.3389/fvets.2023.1297158. eCollection 2023.
Bovine respiratory disease (BRD) is a multifactorial disease complex in which bacteria in the upper respiratory tract play an important role in disease development. Previous studies have related the presence of four BRD-pathobionts (, , , and ) in the upper respiratory tract to BRD incidence and mortalities in the dairy and beef cattle industry, but these studies typically only use one time point to compare the abundance of BRD-pathobionts between apparently healthy and BRD-affected cattle. The objective of this study was to characterize the longitudinal development of the nasopharyngeal (NP) microbiome from apparently healthy calves, and in calves with clinical signs of BRD, the microbiota dynamics from disease diagnosis to recovery.
Deep nasopharyngeal swabs were taken from all calves immediately after transport (day 0). If a calf was diagnosed with BRD ( = 10), it was sampled, treated with florfenicol or tulathromycin, and sampled again 1, 5, and 10 days after antibiotic administration. Otherwise, healthy calves ( = 20) were sampled again on days 7 and 14. Bacterial community analysis was performed through 16S rRNA gene amplicon sequencing.
The NP microbiome of the healthy animals remained consistent throughout the study, regardless of time. The NP microbiota beta diversity and community composition was affected by tulathromycin or florfenicol administration. Even though BRD-pathobionts were identified by 16S rRNA gene sequencing in BRD-affected animals, no difference was observed in their relative abundance between the BRD-affected and apparently healthy animals. The abundance of BRD-pathobionts was not predictive of disease development while the relative abundance of BRD pathobionts was unique to each BRD-affected calf. Interestingly, at the end of the study period, the genera was the most abundant genus in the healthy group, while was the most abundant genus in the animals that recovered from BRD.
This study highlights that injected antibiotics seem to improve the NP microbiome composition (higher abundance of and lower abundance of ), and that the relative abundance of BRD-pathobionts differs between individual calves but is not strongly predictive of BRD clinical signs, indicating that additional factors are likely important in the clinical progression of BRD.
牛呼吸道疾病（BRD）是一种多因素疾病复合体，其中上呼吸道细菌在疾病发展中起重要作用。先前的研究已将上呼吸道中四种BRD致病共生菌（、、和）的存在与奶牛和肉牛行业的BRD发病率及死亡率相关联，但这些研究通常仅使用一个时间点来比较看似健康和受BRD影响的牛之间BRD致病共生菌的丰度。本研究的目的是描述看似健康的犊牛鼻咽（NP）微生物组的纵向发育情况，以及患有BRD临床症状的犊牛从疾病诊断到康复的微生物群动态变化。
所有犊牛在运输后立即（第0天）采集深部鼻咽拭子。如果犊牛被诊断为BRD（=10），则对其进行采样，用氟苯尼考或泰拉霉素治疗，并在抗生素给药后1、5和10天再次采样。否则，健康犊牛（=20）在第7天和第14天再次采样。通过16S rRNA基因扩增子测序进行细菌群落分析。
在整个研究过程中，健康动物的NP微生物组保持一致，与时间无关。NP微生物群的β多样性和群落组成受泰拉霉素或氟苯尼考给药的影响。尽管通过16S rRNA基因测序在受BRD影响的动物中鉴定出了BRD致病共生菌，但在受BRD影响的动物和看似健康的动物之间，未观察到它们相对丰度的差异。BRD致病共生菌的丰度不能预测疾病的发展，而BRD致病共生菌的相对丰度在每头受BRD影响的犊牛中是独特的。有趣的是，在研究期结束时，属是健康组中最丰富的属，而属是从BRD中康复的动物中最丰富的属。
本研究强调，注射用抗生素似乎可改善NP微生物组组成（属丰度较高而属丰度较低），并且BRD致病共生菌的相对丰度在个体犊牛之间存在差异，但不能强烈预测BRD临床症状，这表明其他因素可能在BRD的临床进展中很重要。
