Dipartimento di Medicina Veterinaria, Università di Sassari, Sassari, Italy.
Istituto Zooprofilattico Sperimentale della Sardegna, Centro di Referenza Nazionale per le Mastopatie degli Ovini e dei Caprini, Sassari, Italy.
Vet Res Commun. 2022 Jun;46(2):329-351. doi: 10.1007/s11259-022-09901-y. Epub 2022 Feb 23.
Mastitis is one of the most impacting diseases in dairy farming, and its sensitive and specific detection is therefore of the greatest importance. The clinical evaluation of udder and mammary secretions is typically combined with the milk Somatic Cell Count (SCC) and often accompanied by its bacteriological culture to identify the causative microorganism. In a constant search for improvement, several non-enzymatic milk proteins, including milk amyloid A (M-SAA), haptoglobin (HP), cathelicidin (CATH), and lactoferrin (LF), have been investigated as alternative biomarkers of mastitis for their relationship with mammary gland inflammation, and immunoassay techniques have been developed for detection with varying degrees of success. To provide a general overview of their implementation in the different dairy species, we carried out a systematic review of the scientific literature using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines. Our review question falls within the type "Diagnostic test accuracy questions" and aims at answering the diagnostic question: "Which are the diagnostic performances of mastitis protein biomarkers investigated by immunoassays in ruminant milk?". Based on 13 keywords combined into 42 searches, 523 manuscripts were extracted from three scientific databases. Of these, 33 passed the duplicate removal, title, abstract, and full-text screening for conformity to the review question and document type: 78.8% investigated cows, 12.1% sheep, 9.1% goats, and 6.1% buffaloes (some included more than one dairy species). The most frequently mentioned protein was M-SAA (48.5%), followed by HP (27.3%), CATH (24.2%) and LF (21.2%). However, the large amount of heterogeneity among studies in terms of animal selection criteria (45.5%), index test (87.9%), and standard reference test (27.3%) resulted in a collection of data not amenable to meta-analysis, a common finding illustrating how important it is for case definitions and other criteria to be standardized between studies. Therefore, results are presented according to the SWiM (Synthesis Without Meta-analysis) guidelines. We summarize the main findings reported in the 33 selected articles for the different markers and report their results in form of comparative tables including sample selection criteria, marker values, and diagnostic performances, where available. Finally, we report the study limitations and bias assessment findings.
乳腺炎是奶牛养殖业中最具影响力的疾病之一，因此，对其进行敏感和特异的检测至关重要。通常将乳房和乳状分泌物的临床评估与牛奶体细胞计数（SCC）相结合，并经常伴随其细菌培养以确定致病微生物。为了不断寻求改进，人们研究了几种非酶牛奶蛋白，包括牛奶淀粉样蛋白 A（M-SAA）、触珠蛋白（HP）、抗菌肽（CATH）和乳铁蛋白（LF），作为乳腺炎的替代生物标志物，因为它们与乳腺炎症有关，并且已经开发出免疫测定技术来检测它们，其成功率各不相同。为了提供它们在不同奶牛物种中的应用的总体概述，我们根据 PRISMA（系统评价和荟萃分析的首选报告项目）指南对科学文献进行了系统回顾。我们的综述问题属于“诊断测试准确性问题”类型，旨在回答以下诊断问题：“通过免疫测定在反刍动物乳中研究的乳腺炎蛋白生物标志物的诊断性能如何？”。基于 13 个关键词组合成的 42 个搜索，从三个科学数据库中提取了 523 篇论文。其中，33 篇通过重复去除、标题、摘要和全文筛选符合审查问题和文献类型的标准：78.8%的研究对象为奶牛，12.1%为绵羊，9.1%为山羊，6.1%为水牛（有些包含不止一种奶牛）。提到最多的蛋白是 M-SAA（48.5%），其次是 HP（27.3%）、CATH（24.2%）和 LF（21.2%）。然而，由于动物选择标准（45.5%）、索引测试（87.9%）和标准参考测试（27.3%）方面的研究之间存在大量异质性，导致无法进行荟萃分析，这一常见发现说明了在研究之间标准化病例定义和其他标准是多么重要。因此，根据 SWiM（无荟萃分析综合）指南，我们根据报告的不同标记物的主要发现进行了总结，并以表格形式报告了其结果，其中包括样本选择标准、标记物值和诊断性能（如有）。最后，我们报告了研究的局限性和偏倚评估结果。
