Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Königsweg 65, 14163 Berlin, Germany.
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Königsweg 65, 14163 Berlin, Germany.
J Dairy Sci. 2021 Feb;104(2):2106-2122. doi: 10.3168/jds.2020-18539. Epub 2020 Dec 23.
Timely and objective diagnosis and classification of mastitis is crucial to ensure adequate management and therapeutic decisions. Analyzing specific biomarkers in milk could be advantageous compared with subjective or semiquantitative criteria, such as palpation of the udder in clinical mastitis cases or evaluation of somatic cell count using cow side tests (e.g., California Mastitis Test) in subclinical mastitis quarters. The objective of this study was to investigate the diagnostic value of 3 biomarkers; cathelicidin, milk amyloid A, and haptoglobin for the diagnosis of subclinical and clinical mastitis. Furthermore, the suitability of these biomarkers to differentiate between mild, moderate, and severe clinical mastitis and the influence of different pathogens on biomarker levels was tested. A total of 67 healthy cows, 119 cows with subclinical mastitis, and 212 cows with clinical mastitis were enrolled in the study. Although cathelicidin, haptoglobin, and milk amyloid A were measured in all samples from healthy cows and those with subclinical mastitis, haptoglobin, and cathelicidin results were only available from 121 out of 212 cows with clinical mastitis. Milk amyloid A was measured in all samples. In cows with clinical mastitis, the mastitic quarter and a second healthy quarter serving as a healthy in-cow control quarter were sampled. It was possible to differentiate between healthy quarters, quarters with subclinical mastitis, and quarters with clinical mastitis using all 3 biomarkers. Concerning cathelicidin, thresholds were 0.000 [sensitivity (Se) = 0.83, specificity (Sp) = 0.97] and 0.053 (Se = 0.98, Sp = 0.99) for normalized optical density at 450 nm (NOD450) for differentiating between healthy quarters and quarters with subclinical or clinical mastitis, respectively. Thresholds of 1.28 µg/mL (Se = 0.65, Sp = 0.76) and 1.81 µg/mL (Se = 0.77, Sp = 0.83) for milk amyloid A and 3.65 µg/mL (Se = 0.92, Sp = 0.94) and 5.40 µg/mL mL (Se = 0.96, Sp = 0.99) for haptoglobin were calculated, respectively. Healthy in-cow control quarters from cows with CM showed elevated milk amyloid A and haptoglobin levels compared with healthy quarters from healthy cows. Only the level of milk amyloid A was higher in severe clinical mastitis cases compared with mild ones. In contrast to clinical mastitis, cathelicidin and haptoglobin in subclinical mastitis quarters were significantly influenced by different bacteriological results. The measurement of cathelicidin, milk amyloid A, and haptoglobin in milk proved to be a reliable method to detect quarters with subclinical or clinical mastitis.
及时、客观地诊断和分类乳腺炎对于确保充分的管理和治疗决策至关重要。与临床乳腺炎病例中触诊乳房或使用牛侧试验（如加利福尼亚乳腺炎试验）评估体细胞计数等主观或半定量标准相比，分析牛奶中的特定生物标志物可能具有优势。本研究的目的是研究 3 种生物标志物（抗菌肽、乳淀粉样蛋白 A 和触珠蛋白）在诊断亚临床和临床乳腺炎中的诊断价值。此外，还测试了这些生物标志物区分轻度、中度和重度临床乳腺炎的适用性以及不同病原体对生物标志物水平的影响。共纳入 67 头健康奶牛、119 头亚临床乳腺炎奶牛和 212 头临床乳腺炎奶牛。虽然在健康奶牛和亚临床乳腺炎奶牛的所有样本中均测量了抗菌肽、触珠蛋白和乳淀粉样蛋白 A，但只有 212 头临床乳腺炎奶牛中的 121 头提供了触珠蛋白和抗菌肽的结果。所有样本均测量了乳淀粉样蛋白 A。在患有临床乳腺炎的奶牛中，对乳腺炎象限和作为健康牛内对照象限的第二个健康象限进行了采样。使用所有 3 种生物标志物可以区分健康象限、亚临床乳腺炎象限和临床乳腺炎象限。关于抗菌肽，区分健康象限和亚临床或临床乳腺炎象限的 450nm 处归一化光密度（NOD450）的截断值分别为 0.000[灵敏度（Se）=0.83，特异性（Sp）=0.97]和 0.053（Se=0.98，Sp=0.99）。乳淀粉样蛋白 A 的截断值分别为 1.28μg/mL（Se=0.65，Sp=0.76）和 1.81μg/mL（Se=0.77，Sp=0.83），触珠蛋白的截断值分别为 3.65μg/mL（Se=0.92，Sp=0.94）和 5.40μg/mL（Se=0.96，Sp=0.99）。与健康奶牛的健康牛内对照象限相比，患有 CM 的奶牛的健康牛内对照象限的乳淀粉样蛋白 A 和触珠蛋白水平升高。只有严重临床乳腺炎病例的乳淀粉样蛋白 A 水平高于轻度病例。与临床乳腺炎不同，亚临床乳腺炎象限中的抗菌肽和触珠蛋白水平受到不同细菌学结果的显著影响。牛奶中抗菌肽、乳淀粉样蛋白 A 和触珠蛋白的测量被证明是一种可靠的方法，可以检测亚临床或临床乳腺炎的象限。
