Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada; Simpson Ranch Chair in Beef Cattle Health and Wellness, University of Calgary, Calgary, AB, Canada; Feedlot Health Management Services, Okotoks, AB, Canada.
Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
Vet Microbiol. 2018 Jul;221:105-113. doi: 10.1016/j.vetmic.2018.06.007. Epub 2018 Jun 8.
Specific nasopharyngeal bacterial communities can provide colonization resistance against respiratory pathogens in cattle. However, the role of bacterial communities of the lower airways in respiratory health remains largely unknown. Therefore, our objective was to compare nasopharyngeal and tracheal bacterial communities between healthy feedlot cattle and those with bronchopneumonia (BP). Deep nasal swabs and trans-tracheal aspiration samples were collected from steers with (n = 60) and without (n = 60) BP at 4 feedlots in Western Canada. After DNA extraction, 16S rRNA gene (V4) was amplified and sequenced. Alpha-diversity analysis revealed a lower bacterial diversity in the nasopharynx and trachea of steers with BP compared to healthy pen-mates. Bacterial communities present within the airways clustered into 4 distinct metacommunities that were associated with sampling locations and health status. Metacommunity 1, enriched with Mycoplasma bovis, Mannheimia haemolytica and Pasteurella multocida, was dominant in the nasopharynx and trachea of steers with BP. In contrast, metacommunity 3, enriched with Mycoplasma dispar, Lactococcus lactis and Lactobacillus casei, was mostly present in the trachea of healthy steers. Metacommunity 4, enriched with Corynebacterium, Jeotgalicoccus, Psychrobacter and Planomicrobium, was present in the nasopharynx only. Metacommunity 2, enriched with Histophilus somni, Moraxella and L. lactis, was present in both healthy and sick steers, but was primarily detected in one feedlot. We concluded that distinct bacterial metacommunities inhabited the nasopharynx and trachea of healthy feedlot cattle and those with BP. Because L. lactis and L. casei can inhibit M. haemolytica growth in vitro, their presence in healthy steers may have provided colonization resistance against bacterial respiratory pathogens.
特定的鼻咽细菌群落可以为牛提供针对呼吸道病原体的定植抗性。然而，下呼吸道细菌群落在呼吸道健康中的作用在很大程度上仍然未知。因此，我们的目标是比较健康育肥牛和患有支气管肺炎（BP）的牛的鼻咽和气管细菌群落。在加拿大西部的 4 个牧场，从患有 BP（n=60）和无 BP（n=60）的育肥牛中采集深鼻咽拭子和经气管抽吸样本。提取 DNA 后，扩增和测序 16S rRNA 基因（V4）。α多样性分析表明，与健康同栏牛相比，BP 牛的鼻咽和气管中的细菌多样性较低。存在于气道内的细菌群落聚类为 4 个不同的元群落，与采样地点和健康状况相关。元群落 1 富含牛支原体、溶血曼氏杆菌和多杀巴斯德氏菌，在 BP 牛的鼻咽和气管中占主导地位。相比之下，元群落 3 富含差异支原体、乳球菌和干酪乳杆菌，主要存在于健康育肥牛的气管中。元群落 4 富含棒状杆菌、詹氏球菌、假单胞菌和 Planomicrobium，仅存在于鼻咽中。元群落 2 富含豪氏霍尔氏菌、莫拉氏菌和乳球菌，存在于健康和患病的育肥牛中，但主要存在于一个牧场中。我们得出结论，不同的细菌元群落栖息在健康育肥牛和患有 BP 的牛的鼻咽和气管中。由于乳球菌和干酪乳杆菌可以在体外抑制溶血曼氏杆菌的生长，它们在健康育肥牛中的存在可能为细菌呼吸道病原体提供了定植抗性。
