Department Population Health Sciences, Faculty of Veterinary Medicine, University of Utrecht, Utrecht, The Netherlands.
Department of Basic Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
Sci Rep. 2020 Oct 23;10(1):18172. doi: 10.1038/s41598-020-75179-2.
Intramammary infections (IMI) with Staphylococcus aureus are a common cause of bovine mastitis and can result in both clinical (CM) or subclinical mastitis (SCM). Although bacterial isolates of S. aureus differ in their virulence potential it is largely unclear which bacterial virulence factors are responsible for increased clinical severity. We performed a genome wide association study and used a generalized linear mixed model to investigate the correlation between gene carriage, lineage and clinical outcome of IMI in a collection of S. aureus isolates from cattle with CM (n = 125) and SCM (n = 151) from 11 European countries. An additional aim was to describe the genetic variation of bovine S. aureus in Europa. The dominant lineages in our collection were clonal complex (CC) 151 (81/276, 29.3%), CC97 (54/276, 19.6%), CC479 (32/276, 11.6%) and CC398 (19/276, 6.9%). Virulence and antimicrobial resistance (AMR) gene carriage was highly associated with CC. Among a selection of nine virulence and AMR genes, CC151, CC479 and CC133 carried more virulence genes than other CCs, and CC398 was associated with AMR gene carriage. Whereas CC151, CC97 were widespread in Europe, CC479, CC398 and CC8 were only found in specific countries. Compared to CC151, CC479 was associated with CM rather than SCM (OR 3.62; 95% CI 1.38-9.50) and the other CCs were not. Multiple genes were associated with CM, but due to the clustering within CC of carriage of these genes, it was not possible to differentiate between the effect of gene carriage and CC on clinical outcome of IMI. Nevertheless, this study demonstrates that characterization of S. aureus CC and virulence genes helps to predict the likelihood of the occurrence of CM following S. aureus IMI and highlights the potential benefit of diagnostics tools to identify S. aureus CC during bovine mastitis.
金黄色葡萄球菌引起的乳房内感染（IMI）是奶牛乳腺炎的常见病因，可导致临床型乳腺炎（CM）或亚临床型乳腺炎（SCM）。尽管金黄色葡萄球菌的分离株在毒力潜能上存在差异，但目前尚不清楚哪些细菌毒力因子与临床严重程度的增加有关。我们进行了全基因组关联研究，并使用广义线性混合模型，调查了来自 11 个欧洲国家的患有 CM（n=125）和 SCM（n=151）的奶牛的金黄色葡萄球菌分离株的基因携带、谱系与 IMI 临床结果之间的相关性。本研究的另一个目的是描述 Europa 地区的牛源金黄色葡萄球菌的遗传变异。我们的研究中分离株主要来源于克隆复合体（CC）151（81/276，29.3%）、CC97（54/276，19.6%）、CC479（32/276，11.6%）和 CC398（19/276，6.9%）。毒力和抗菌药物耐药（AMR）基因携带与 CC 高度相关。在选择的 9 个毒力和 AMR 基因中，CC151、CC479 和 CC133 携带的毒力基因多于其他 CC，而 CC398 与 AMR 基因携带相关。CC151 和 CC97 在欧洲广泛分布，而 CC479、CC398 和 CC8 仅在特定国家发现。与 CC151 相比，CC479 与 CM 相关，而不是 SCM（比值比 3.62；95%置信区间 1.38-9.50），而其他 CC 则没有。多个基因与 CM 相关，但由于这些基因在 CC 内的携带情况存在聚类，因此无法区分基因携带和 CC 对 IMI 临床结果的影响。然而，本研究表明，金黄色葡萄球菌 CC 和毒力基因的特征有助于预测金黄色葡萄球菌 IMI 后 CM 的发生可能性，并强调了在奶牛乳腺炎期间使用诊断工具识别金黄色葡萄球菌 CC 的潜在益处。
