Peña-Mosca F, Gaire T N, Dean C, Ferm P, Manriquez D, Pinedo P, Noyes N, Caixeta L
Department of Veterinary Population Medicine, University of Minnesota, St. Paul, MN, United States.
Department of Public and Ecosystem Health, Cornell University, Ithaca, NY, United States.
Front Microbiol. 2025 Sep 1;16:1614488. doi: 10.3389/fmicb.2025.1614488. eCollection 2025.
Prior studies have suggested that non- and (NASM) possess inhibitory activity against mastitis pathogens. However, their impact on udder health outcomes and the mechanisms underlying this potential protective effect remain poorly understood. Our first objective was to identify NASM species on teat apices of organic dairy cows, assess their within-species phylogeny, and explore associations with presence of intramammary infections (IMI) and genomic features, including antimicrobial peptides (AMPs), virulence, and resistance genes. The second objective was to evaluate the antimicrobial activity of NASM isolates against mastitis pathogens and examine its associations with taxonomy, phylogeny, AMP genes, and IMI. Milk and teat apex swabs were collected weekly from 114 cows on two organic farms. Milk was cultured to identify (SAU) or spp. and -like organisms (SSLO) IMI. A case-control study was designed to include cows with and without SAU or SSLO IMI. For each selected cow, the teat apex gauze swab collected during the week preceding IMI diagnosis (or corresponding time for controls) was aerobically cultured, and the taxonomy of isolates was determined using mass spectrometry. Isolates classified as NASM were subjected to whole genome sequencing using Illumina MiSeq. The inhibitory activity of NASM isolates was tested against SAU and Phylogenetic trees were constructed using Snippy and IQ-TREE. Genomes were assembled and annotated to identify species, AMP genes, virulence, and antimicrobial resistance markers. The antimicrobial activity of NASM varied across species and between cows with and without an IMI. was the species most frequently associated with highly inhibitory isolates, which were more prevalent in cows without IMI (19.4% vs. 5.8%). Organic dairy cow teat apices harbored multiple NASM species and strains. All isolates had at least 1 AMP associated gene in their genome. antimicrobial activity was generally unrelated to clade membership, except for isolates classified as . had high virulence gene prevalence, while NASM species showed lower, species-specific prevalence. This study advances understanding of NASM antimicrobial activity and virulence potential.
先前的研究表明，非金黄色葡萄球菌和凝固酶阴性葡萄球菌（NASM）对乳腺炎病原体具有抑制活性。然而，它们对乳房健康结果的影响以及这种潜在保护作用的潜在机制仍知之甚少。我们的首要目标是鉴定有机奶牛乳头顶端的NASM种类，评估它们的种内系统发育，并探索与乳房内感染（IMI）的存在以及基因组特征（包括抗菌肽（AMP）、毒力和抗性基因）之间的关联。第二个目标是评估NASM分离株对乳腺炎病原体的抗菌活性，并研究其与分类学、系统发育、AMP基因和IMI的关联。每周从两个有机农场的114头奶牛中采集牛奶和乳头顶端拭子。对牛奶进行培养以鉴定金黄色葡萄球菌（SAU）或无乳链球菌属（Streptococcus agalactiae）及无乳链球菌样菌（SSLO）引起的IMI。设计了一项病例对照研究，纳入有和没有SAU或SSLO引起的IMI的奶牛。对于每头选定的奶牛，在IMI诊断前一周（或对照组的相应时间）采集的乳头顶端纱布拭子进行需氧培养，并使用质谱法确定分离株的分类学。分类为NASM的分离株使用Illumina MiSeq进行全基因组测序。测试NASM分离株对SAU和无乳链球菌的抑制活性。使用Snippy和IQ-TREE构建系统发育树。对基因组进行组装和注释，以鉴定物种、AMP基因、毒力和抗菌抗性标记。NASM的抗菌活性在不同物种之间以及有和没有IMI的奶牛之间有所不同。科氏葡萄球菌（Staphylococcus cohnii）是最常与高抑制性分离株相关的物种，在没有IMI的奶牛中更普遍（19.4%对5.8%）。有机奶牛乳头顶端存在多种NASM物种和菌株。所有分离株在其基因组中至少有1个与AMP相关的基因。抗菌活性一般与进化枝成员无关，除了分类为科氏葡萄球菌的分离株。无乳链球菌的毒力基因流行率较高，而NASM物种显示出较低的、物种特异性的流行率。这项研究推进了对NASM抗菌活性和毒力潜力的理解。
