National Veterinary Institute, Technical University of Denmark, Kemitorvet Build. 204, 2800 Kgs. Lyngby, Denmark.
Section for Production, Nutrition and Health, University of Copenhagen, Grønnegårdsvej 2, 1870 Fdr. C, Denmark.
Vet Microbiol. 2018 Feb;215:35-42. doi: 10.1016/j.vetmic.2018.01.003. Epub 2018 Jan 9.
Staphylococcus aureus is one of the most common pathogens that cause mastitis in dairy cows. Various subtypes, virulence genes and mobile genetic elements have been associated with isolates from bulk tank milk and clinical mastitis. So far, no Danish cattle associated S. aureus isolates have been whole-genome sequenced and further analyzed. Thus, the main objective was to investigate the population structure and genomic content of isolates from bulk tank milk and clinical mastitis, using whole-genome sequencing. This may reveal the origin of strains that cause clinical mastitis. S. aureus isolates from bulk tank milk (n = 94) and clinical mastitis (n = 63) were collected from 91 and 24 different farms, respectively and whole-genome sequenced. The genomic content was analyzed and a phylogenetic tree based on single nucleotide polymorphisms was constructed. In general, the isolates from both bulk tank milk and clinical mastitis were of similar genetic background. This suggests that dairy cows are natural carriers of the S. aureus subtypes that cause clinical mastitis if the right conditions are present and that a broad range of subtypes cause mastitis. A phylogenetic cluster that mostly consisted of ST151 isolates carried three mobile genetic elements that were primarily found in this group. The prevalence of resistance genes was generally low. However, the first ST398 methicillin resistant S. aureus isolate from a Danish dairy cow with clinical mastitis was detected.
金黄色葡萄球菌是引起奶牛乳腺炎最常见的病原体之一。各种亚型、毒力基因和可移动遗传元件与来自奶罐奶和临床乳腺炎的分离株有关。到目前为止，还没有对丹麦牛相关的金黄色葡萄球菌分离株进行全基因组测序和进一步分析。因此，主要目的是使用全基因组测序来研究奶罐奶和临床乳腺炎分离株的种群结构和基因组内容。这可能揭示引起临床乳腺炎的菌株的起源。从 91 个不同的农场收集了 94 份奶罐奶和 63 份临床乳腺炎的金黄色葡萄球菌分离株，并进行了全基因组测序。分析了基因组内容，并构建了基于单核苷酸多态性的系统发育树。一般来说，来自奶罐奶和临床乳腺炎的分离株具有相似的遗传背景。这表明，如果条件合适，奶牛是引起临床乳腺炎的金黄色葡萄球菌亚型的天然携带者，而且多种亚型会引起乳腺炎。一个主要由 ST151 分离株组成的系统发育群携带了三个主要在该群中发现的可移动遗传元件。耐药基因的流行率通常较低。然而，检测到了第一株来自丹麦患有临床乳腺炎奶牛的 ST398 耐甲氧西林金黄色葡萄球菌分离株。
