重组溶葡萄球菌酶对金葡菌诱导试验性小鼠乳腺炎的防治研究

试验采用重组溶葡萄球菌酶探讨了对小鼠试验性乳腺炎的治疗效果.利用微量肉汤稀释法测定了重组溶葡萄球菌酶时乳源金黄色葡萄球菌(Staphylococcus aureus)的最小抑菌浓度(MIC)和最小杀菌浓度(MBC).将18只泌乳8～10 d的BALB/C母鼠随机分成正常组、阳性对照组和试验组.阳性时照组和试验组母鼠经第4对、第5对乳腺乳头管注入50μL 2.0x105CFU的细菌悬液.试验组攻菌出现症状后,每个乳腺经乳头管注入1 U·mL-1的重组溶葡萄球菌酶稀释液50μL,间隔12 h 1次.观察小鼠的临床症状,测定体温、血常规等指标.接菌66h后,颈静脉放血处死小鼠,取小鼠乳腺进行细菌计数和病理组织切片制作.结果显示,重组溶葡萄球菌酶对金黄色葡萄球菌的MIC值为0.001 U·mL-1,MBC值为0.063U·mL-1.病理组织观察显示,正常组的腺泡结构完整,而阳性对照组的乳腺组织局部被破坏,间质增宽,炎性细胞浸润严重,试验组的组织结构基本正常,有轻度充血.说明重组溶葡萄球菌酶能有效地减少细菌感染,降低组织的损伤程度,对乳腺有一定地保护作用.

The Study of Recombinant Lysostaphin on the Prevention and Treatment of Experimental Mastitis in Mice Induced by Staphylococcus aureus

In order to study the treatment result of recombinant lysostaphin on experimental mastitis in mice induced by Staphylococcus aweus. A trace broth dilution was used for determination of the MICs and MBCs of recombinant lysostaphin against S. aureus clinically isolated from mastitis cows. Eighteen pregnant BALB/C mice randomly divided into normal control group,positive control group and treatment group. 50 μL 2.0×10~5CFU S. aureus was inoculated into the fourth mammary gland on 8～10 d after parturition. 50μL 1U·mL~(-1) recombinant lysostaphin was injected into the cavity of every mammary gland after symptoms of treatment group was obvious,and once every 12 h. The clinical symptoms were observed. The body temperature,blood and other indicators were measured. 66 h after inoculation,the mice were euthanatized and the mammary glands were removed and fixed for histopathologic evaluations. The MICs of recombinant lysostaphin was 0.001 U·mL~(-1) and the MBCs was 0.063 U·mL~(-1). Histopathologic examination of mammary gland revealed that the mammary glands frame of normal group was integrated. Some mammary gland frame of positive control group was damaged,the interstitial width increased,and a large number of inflammatory cells aggregated. The frame of treatment group was basically normal,organization was lightly congestive. Recombinant lysostaphin was effective in reducing the bacterial infection and tissue injury. The mammary glands could be protected by recombinant lysostaphin.