Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute, Uppsala, Sweden.
Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
PLoS One. 2020 Dec 2;15(12):e0242880. doi: 10.1371/journal.pone.0242880. eCollection 2020.
Udder cleft dermatitis (UCD) is a skin condition affecting the fore udder attachment of dairy cows. UCD may be defined as mild (eczematous skin changes) or severe (open wounds, large skin changes). Our aims were to compare the microbiota of mild and severe UCD lesions with the microbiota of healthy skin from the fore udder attachment of control cows, and to investigate whether mastitis-causing pathogens are present in UCD lesions. Samples were obtained from cows in six dairy herds. In total, 36 UCD samples categorized as mild (n = 17) or severe (n = 19) and 13 control samples were sequenced using a shotgun metagenomic approach and the reads were taxonomically classified based on their k-mer content. The Wilcoxon rank sum test was used to compare the abundance of different taxa between different sample types, as well as to compare the bacterial diversity between samples. A high proportion of bacteria was seen in all samples. Control samples had a higher proportion of archaeal reads, whereas most samples had low proportions of fungi, protozoa and viruses. The bacterial microbiota differed between controls and mild and severe UCD samples in both composition and diversity. Subgroups of UCD samples were visible, characterized by increased proportion of one or a few bacterial genera or species, e.g. Corynebacterium, Staphylococcus, Brevibacterium luteolum, Trueperella pyogenes and Fusobacterium necrophorum. Bifidobacterium spp. were more common in controls compared to UCD samples. The bacterial diversity was higher in controls compared to UCD samples. Bacteria commonly associated with mastitis were uncommon. In conclusion, a dysbiosis of the microbiota of mild and severe UCD samples was seen, characterized by decreased diversity and an increased proportion of certain bacteria. There was no evidence of a specific pathogen causing UCD or that UCD lesions are important reservoirs for mastitis-causing bacteria.
奶牛乳房裂缝性皮炎（UCD）是一种影响奶牛前乳房附着的皮肤状况。UCD 可定义为轻度（湿疹样皮肤变化）或重度（开放性伤口，皮肤大面积变化）。我们的目的是比较轻度和重度 UCD 病变与来自对照奶牛前乳房附着的健康皮肤的微生物组，并研究乳腺炎病原体是否存在于 UCD 病变中。样本取自六个奶牛场的奶牛。总共获得了 36 个 UCD 样本，分为轻度（n=17）或重度（n=19），以及 13 个对照样本，使用 shotgun 宏基因组方法进行测序，并根据 k-mer 含量对读取进行分类。使用 Wilcoxon 秩和检验比较不同样本类型之间不同分类单元的丰度，以及比较样本之间的细菌多样性。所有样本中均存在大量细菌。对照样本中具有较高比例的古细菌读段，而大多数样本中真菌、原生动物和病毒的比例较低。对照样本和轻度和重度 UCD 样本的细菌微生物组在组成和多样性上均存在差异。可以看到 UCD 样本的亚群，其特征是一个或少数几个细菌属或种的比例增加，例如 Corynebacterium、Staphylococcus、Brevibacterium luteolum、Trueperella pyogenes 和 Fusobacterium necrophorum。与 UCD 样本相比，双歧杆菌属在对照样本中更为常见。与 UCD 样本相比，对照样本的细菌多样性更高。与乳腺炎相关的细菌不常见。总之，轻度和重度 UCD 样本的微生物组失调，表现为多样性降低和某些细菌比例增加。没有证据表明特定病原体引起 UCD，或 UCD 病变是乳腺炎病原体的重要储存库。
