Abstract：
Bovine mastitis (BM) is a prevalent infectious disease in dairy herds worldwide, resulting in substantial economic losses. Staphylococcus aureus is a major cause of mastitis in animals, and its antibiotic resistance poses challenges for treatment. Recently, there has been a renewed interest in the development of alternative methods to antibiotic therapy, including bacteriophages (phages), for controlling bacterial infections. In this study, 2 lytic phages (designated as JDYN for vB_SauM_JDYN and JDF86 for vB_SauM_JDF86) were isolated from the cattle sewage effluent samples collected from dairy farms in Shanghai. The 2 phages have a broad bactericidal spectrum against Staphylococcus of various origins. Genomic and morphological analyses revealed that the 2 phages belonged to the Myoviridae family. Moreover, JDYN and JDF86 remained stable under a wide range of temperatures or pH and were almost unaffected in chloroform. In this study, we prepared a phage cocktail designated \"PHC-1\" which consisted of a 1:1:1 ratio of JDYN, JDF86 and SLPW (a previously characterized phage). PHC-1 showed the strongest bacteriolytic effect and the lowest frequency of emergence of bacteriophage insensitive mutants compared with monophages. The bovine mammary epithelial cells (MAC-T cells) and lactating mice mastitis model were used to evaluate the effectiveness of PHC-1 in vitro and in vivo, respectively. The results demonstrated that PHC-1 treatment significantly reduced bacterial load, alleviated inflammatory response, and improved mastitis pathology. Altogether, these results suggest that PHC-1 has the potential to treat S. aureus-induced bovine mastitis and that phage cocktails can combat antibiotic-resistant S. aureus infections.
摘要：
奶牛乳腺炎(BM)是世界范围内奶牛群中普遍存在的一种传染病,造成了巨大的经济损失。金黄色葡萄球菌是引起动物乳腺炎的主要原因,其抗生素耐药性对治疗提出了挑战。最近,人们对开发抗生素治疗的替代方法重新产生了兴趣，包括噬菌体（噬菌体），用于控制细菌感染。在这项研究中,从上海奶牛场收集的牛污水样本中分离出2个裂解噬菌体（vB_SauM_JDYN命名为JDYN，vB_SauM_JDF86命名为JDF86）。2种噬菌体具有针对各种来源的葡萄球菌的广泛杀菌谱。基因组和形态分析表明，这2种噬菌体属于Myoviridae家族。此外，JDYN和JDF86在宽范围的温度或pH下保持稳定，在氯仿中几乎不受影响。在这项研究中,我们准备了一种名为“PHC-1”的噬菌体鸡尾酒，它由1:1:1的JDYN组成，JDF86和SLPW(先前表征的噬菌体)。与单噬菌体相比，PHC-1显示出最强的溶菌作用和最低的噬菌体不敏感突变体出现频率。用奶牛乳腺上皮细胞(MAC-T细胞)和泌乳小鼠乳腺炎模型评价PHC-1的体内外效果,分别。结果表明，PHC-1处理显著降低细菌负荷，减轻炎症反应，和改善乳腺炎病理。总之,这些结果表明,PHC-1具有治疗金黄色葡萄球菌诱导的牛乳腺炎的潜力,并且噬菌体混合物可以对抗抗生素耐药的金黄色葡萄球菌感染.
