Bristol Veterinary School, University of Bristol, Langford, UK.
Rothamsted Research, North Wyke, Devon, UK.
Sci Rep. 2019 Aug 16;9(1):11943. doi: 10.1038/s41598-019-48007-5.
We investigated three bovine respiratory pathobionts in healthy cattle using qPCR optimised and validated to quantify Histophilus somni, Mannheimia haemolytica and Pasteurella multocida over a wide dynamic range. A longitudinal study was conducted to investigate the carriage and density of these bacteria in the nasal passages of healthy beef calves (N = 60) housed over winter in an experimental farm setting. The three pathobiont species exhibited remarkably different carriage rates and density profiles. At housing, high carriage rates were observed for P. multocida (95%), and H. somni (75%), while fewer calves were positive for M. haemolytica (13%). Carriage rates for all three bacterial species declined over the 75-day study, but not all individuals became colonised despite sharing of environment and airspace. Colonisation patterns ranged from continuous to intermittent and were different among pathobiont species. Interval-censored exponential survival models estimated the median duration of H. somni and P. multocida carriage at 14.8 (CI: 10.6-20.9) and 55.5 (CI: 43.3-71.3) days respectively, and found higher density P. multocida carriage was associated with slower clearance (p = 0.036). This work offers insights into the dynamics of pathobiont carriage and provides a potential platform for further data collection and modelling studies.
我们使用经过优化和验证的 qPCR 来定量研究健康牛中的三种牛呼吸道病原菌，以涵盖广泛的动态范围。我们进行了一项纵向研究，以调查这些细菌在冬季饲养在实验农场环境中的健康肉牛犊（N=60）鼻腔中的携带和密度。这三种病原菌表现出明显不同的携带率和密度分布。在饲养时，多杀巴斯德菌（95%）和溶血性曼海姆菌（75%）的携带率较高，而 fewer 头犊牛为嗜血杆菌属（13%）阳性。在 75 天的研究中，所有三种细菌的携带率均下降，但并非所有个体都被定植，尽管它们共享环境和空气空间。定植模式从连续到间歇性不等，并且在病原菌之间存在差异。间隔censored 指数生存模型估计溶血性曼海姆菌和多杀巴斯德菌的携带中位数分别为 14.8（CI：10.6-20.9）和 55.5（CI：43.3-71.3）天，并且发现更高密度的多杀巴斯德菌携带与清除速度较慢相关（p=0.036）。这项工作提供了对病原菌携带动态的深入了解，并为进一步的数据收集和建模研究提供了潜在的平台。
