金黄色葡萄球菌小菌落突变株感染小鼠乳房炎模型的建立

Estabishment of Mastitis Model in Mouse by Artificial Infection of Staphylococcus aureus Small Colony Variants

为了建立由金黄色葡萄球菌小菌落突变株（small colony variants，SCVs）诱发感染乳房炎动物模型，本试验取40只分娩6-8d的BALB／c小鼠，随机分成8组（n=5），分别为阴性对照、生理盐水组和不同剂量金黄色葡萄球菌SCVs及金黄色葡萄球菌质控菌株（1．0×10^3、1．0×10^4、1．0×10^5CFU／mL）试验组，对生理盐水组及各试验组小鼠第4对乳腺注射生理盐水和对应剂量的菌液（50mL／只），注射后24h解剖观察病理变化，一侧乳头制作石蜡切片，另一侧研磨后用ELISA检测试剂盒检测组织匀浆上清中的TNF-α含量。结果显示，注射菌液的试验组，小鼠均出现不同程度的临床症状，乳腺出现不同程度的炎性症状和病理变化。同一注射剂量下，金黄色葡萄球菌质控菌株较金黄色葡萄球菌SCVs病理变化严重，通过SPSS等软件对试验数据进行统计分析后得出，高浓度处理组金黄色葡萄球菌质控菌株的TNF-α表达量极显著高于金黄色葡萄球菌SCVs（P〈0．01）。结果表明，金黄色葡萄球菌及其SCVs均可用来建立小鼠乳房炎模型，且金黄色葡萄球菌SCVs引起的情况较其正常株轻微，这一结果为由金黄色葡萄球菌SCVs引起的奶牛慢性乳房炎的预防和控制及其致病机制的研究提供了新的材料和有益的探索，为SCVs与慢性乳房炎更深层次关系的研究奠定基础。

In order to establish the mouse mastitis model induced by Staphylococcus aureus small colony variants （SCVs）,40 BALB/c mice 6 to 8 days postpartum were randomly divided into eight groups,negative control group, physiologic saline group and six treated groups with differ- ent doses （1.0 × 10^3 , 1.0 × 10^4 and 1.0 × l0^5 CFU/mL） of Staphylococcus aureus SCVs or Staph- ylococcus aureus quality control strains. 50 μL physiologic saline and Staphylococcus aureus liquid were injected into the forth mammary glands in physiologic saline group and the six treated groups,respectively. All the mice were sacrificed 24 h after treatment. One side of the forth mam- mary glands was used to make pathological section, the other side was used to detect the concen- tration of TNF-α in the supernatant. The results showed that mice had different degrees of clinical symptoms in the treated groups, their mammary glands appeared different degrees of inflammato- ry symptoms and pathological changes. Under the same injected dose, the Staphylococcus aureus quality control strains group pathologic changed more severe than the Staphylococcus aureus SCVs group. The experimental data had been statistically analyzed by using SPSS software, the result showed that the expression of TNF-α of the Staphylococcus aureus quality control strains group were extremely significantly higher than that of Staphylococcus aureus SCVs group with high dose （P〈0.01）. The results indicated that Staphylococcus aureus and its SCVs could be used to establish the mice mastitis model,and Staphylococcus aureus SCVs caused relatively mi- nor inflammation than the normal strains. The results provided a new research materials and meaningful exploration to research the prevention and control of chronic mastitis cows and its pathogenic mechanism caused by Staphylococcus aureus SCVs, and laid the foundation for stud- ying the deeper relationship between Staphylococcus aureus SCVs and chronic mastitis.