Department of Veterinary and Animal Science University of Copenhagen, Copenhagen, Denmark.
DNA Diagnostic, Risskov, Denmark.
Vet Microbiol. 2021 Aug;259:109135. doi: 10.1016/j.vetmic.2021.109135. Epub 2021 May 27.
Bovine respiratory disease (BRD) is caused by a mixture of viruses and opportunistic bacteria belonging to Pasteurellaceae and Mycoplasma bovis. However, these organisms are also commonly isolated from healthy calves. This study aimed to determine whether the organisms are present in higher numbers in calves sick with acute BRD than in clinically healthy calves, and further to genetically characterize bacteria of the family Pasteurellaceae to understand whether particular types are associated with disease. Forty-six clinically healthy and 46 calves with BRD were sampled by broncheoalveolar lavage (BAL) method in 11 herds geographically spread over Denmark to determine presence and quantity of microorganisms by culture and quantitative real time qPCR. Isolates of Pasteurellaceae were tested for antibiotic resistance and were whole genome sequenced to determine genotypes. Histophilus somni was in particular positively associated with BRD, suggesting particular importance of this organism as likely aetiology of BRD. In addition, quantification of bacteria revealed that higher counts of H. somni as well as of M. haemolytica was also a good indicator of the disease. Pasteurellaceae isolates were susceptible to the commonly used antibiotics in treatment of BRD, and genotypes were shared between isolates from clinically healthy and sick calves.
牛呼吸道疾病（BRD）是由巴氏杆菌科和牛支原体属的病毒和机会性细菌混合引起的。然而，这些生物体也通常从健康的小牛中分离出来。本研究旨在确定患有急性 BRD 的小牛中这些生物体的数量是否高于临床健康的小牛，并且进一步对巴氏杆菌科的细菌进行基因特征分析，以了解是否特定类型与疾病相关。通过支气管肺泡灌洗（BAL）方法从丹麦各地的 11 个牧场采集了 46 头临床健康的小牛和 46 头患有 BRD 的小牛，以通过培养和定量实时 qPCR 确定微生物的存在和数量。巴氏杆菌科的分离物进行了抗生素耐药性测试，并进行了全基因组测序以确定基因型。特别发现嗜血杆菌属与 BRD 呈正相关，这表明该生物体作为 BRD 的可能病因具有特别重要的意义。此外，细菌的定量分析表明，H. somni 和 M. haemolytica 的数量较高也是该疾病的良好指标。巴氏杆菌科的分离物对治疗 BRD 常用的抗生素敏感，并且来自临床健康和患病小牛的分离物具有相同的基因型。
