Caddey Benjamin, Li Mengyue, De Buck Jeroen, Han Bo, Gao Jian, Barkema Herman W
Faculty of Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada.
College of Veterinary Medicine, China Agricultural University, Beijing, People's Republic of China.
Appl Environ Microbiol. 2025 Aug 4:e0067825. doi: 10.1128/aem.00678-25.
is a major bovine mastitis pathogen and can result in chronic intramammary infections that are subject to considerable antimicrobial use. In comparison, non- staphylococci (NAS) are common in intramammary infections, but some strains of NAS reduce risk of clinical mastitis and can inhibit growth . This study aims to determine whether inhibition of growth by NAS species translates to inhibition within a mouse mastitis model and to characterize NAS mammary tissue colonization. Two strains were selected for experimentation to compare genetically similar strains that can and cannot inhibit . Inhibition of growth was tested by pre-inoculating mouse mammary glands with 24 hours prior to inoculation and harvesting mammary gland tissue 24 hours after superinfection. Mammary glands were processed for bacterial load quantification, cytokine profiling, and histological processing. Pre-inoculation of either strain resulted in reduced load in mammary tissue. Superinfection of and showed no difference in inflammation severity compared to alone, although pre-inoculation significantly increased expression of IL-10. These results demonstrate that protection against mastitis is possible by prior colonization of mammary tissue by independent of growth inhibition capacity. This work will foster future research aiming to fully understand the variety of roles NAS strains play in bovine mastitis, aiding in the development toward alternative mastitis prophylaxis.IMPORTANCEBovine mastitis is a leading economic concern for dairy production globally, representing the largest reason for antimicrobial use in dairy cattle. Non- staphylococci (NAS) are among the most frequently isolated bacteria from mild, sometimes self-limiting, intramammary infections in cattle and may be associated with a lower risk of infection by major clinical mastitis pathogens such as . This study investigated the inhibition of mastitis by two NAS strains using an mouse mastitis model. This study demonstrated that when mammary glands are colonized by either one of these NAS strains, the ability of to establish within the mouse mammary glands is reduced. These results demonstrate the long-term potential for NAS strains to become an alternative prophylactic treatment for bovine mastitis and support efforts to reduce antimicrobial dependencies in food production.
是主要的牛乳腺炎病原体，可导致慢性乳腺内感染，这种感染需要大量使用抗菌药物。相比之下，非葡萄球菌（NAS）在乳腺内感染中很常见，但一些NAS菌株可降低临床乳腺炎的风险并能抑制生长。本研究旨在确定NAS菌种对生长的抑制作用在小鼠乳腺炎模型中是否也能转化为抑制作用，并对NAS在乳腺组织中的定植进行表征。选择了两株菌株进行实验，以比较基因相似但能和不能抑制的菌株。在接种前24小时用预先接种小鼠乳腺来测试对生长的抑制作用，并在再次感染后24小时收获乳腺组织。对乳腺进行细菌载量定量、细胞因子分析和组织学处理。预先接种任一菌株均可导致乳腺组织中的载量降低。与单独感染相比，和的再次感染在炎症严重程度上没有差异，尽管预先接种显著增加了IL-10的表达。这些结果表明，乳腺组织预先被定植可预防乳腺炎，而与生长抑制能力无关。这项工作将促进未来的研究，旨在充分了解NAS菌株在牛乳腺炎中所起的各种作用，有助于开发替代乳腺炎预防方法。重要性牛乳腺炎是全球乳制品生产的主要经济问题，是奶牛使用抗菌药物的最大原因。非葡萄球菌（NAS）是牛轻度、有时自限性乳腺内感染中最常分离出的细菌之一，可能与主要临床乳腺炎病原体（如）感染风险较低有关。本研究使用小鼠乳腺炎模型研究了两种NAS菌株对乳腺炎的抑制作用。该研究表明，当乳腺被这些NAS菌株中的任何一种定植时，在小鼠乳腺内定植的能力会降低。这些结果证明了NAS菌株成为牛乳腺炎替代预防性治疗的长期潜力，并支持减少食品生产中对抗菌药物依赖的努力。
