金黄色葡萄球菌致新西兰兔脓胸模型的建立以及尿激酶和脱氧核糖核酸酶Ⅰ的作用研究

Experimental Staphylococcus aureus pleural empyema model in New Zealand rabbits

目的:建立金黄色葡萄球菌脓胸模型,以模拟临床患者胸膜腔金黄色葡萄球菌感染的情况,并探究尿激酶与脱氧核糖核酸酶I(DNase I)联合应用对兔脓胸的影响。方法:将16只新西兰兔随机分为实验组(n=6)、用药组(n=6)和对照组,实验组(n=4);通过胸腔穿刺将引流管置入胸腔,实验组向胸膜腔内注入2 mL/kg的108 CFU/mL金黄色葡萄球菌标准菌株菌液;用药组向胸膜腔内注入等量菌液,并同时注入1 mg DNase I和4 mg尿激酶;对照组向胸腔内注入等量LB肉汤;将引流管植入胸腔内。实验第4天,通过抽取胸腔积液进行革兰染色,同时检测胸腔积液白细胞数、乳酸脱氢酶(LDH)、葡萄糖和pH,判断是否符合脓胸标准。取膈肌面胸膜组织行苏木精-伊红(HE)染色,取引流管进行细菌培养及活菌计数。结果:实验组和用药组兔子胸腔积液混浊,革兰染色发现阳性菌,pH<7.10,LDH>1000 U/L,符合脓胸标准。实验组96 h胸腔积液白细胞计数较用药组高(P<0.05),两组LDH、葡萄糖、pH比较,差异无统计学意义(P>0.05)。实验组胸膜粘连评分和胸膜厚度均明显高于用药组(P<0.05)。结论:将含金黄色葡萄球菌的LB肉汤直接注入新西兰兔胸腔并植入引流管可以成功建立金黄色葡萄球菌脓胸模型;早期联合应用尿激酶和DNase I可以改善胸膜粘连。

Objective:To set up experimental empyema by Staphylococcus aureus in New Zealand rabbits and explore the effect of combined urokinase and deoxyribonucleotide I(DNase I)on rabbit empyema model.Methods:We randomly divided 16 rabbits into three groups:the experimental group,6 rabbits,the medication group,6 rabbits,and the control group,4 rabbits.The 2 mL/kg of 108 CFU/mL Staphylococcus aureus was injected into the experimental group through catheters.In the medication group,the same amount of bacterial fluid was injected into the pleural cavity,and 1 mg DNase and 4 mg urokinase were injected simultaneously.The control group was injected Luria–Bertani(LB)broth,2mL/kg.Then the catheters were placed into the chest and animals were raised normally in clean environment.On the 4th day of the experiment,the pleural fluid was drawn for Gram staining,and the number of leukocytes,lactate dehydrogenase(LDH),glucose,and pH of the pleural fluid were detected to determine whether they met the empyema standard.In addition,the pleura tissue of the diaphragm was taken for hematoxylin-eosin(HE)staining,and the drainage tube was taken for bacterial culture and viable bacteria count.Results:All rabbit pleural effusion specimens of experimental group and medication group were obviously purulent,and Gram-positive bacteria were found,pH<7.10 and LDH>1,000 U/L,which met the empyema standard.The pleural fluid white blood cell count in the experimental group was higher than that in the medication group(P<0.05),and there was no significant difference in LDH,glucose,and pH value(P>0.05)between two groups.The pleural score and pleural thickness of the experimental group were significantly higher than those of the medication group(P<0.05).Conclusion:Injecting LB broth with Staphylococcus au-reus directly into the chest cavity of New Zealand rabbits and early combined application of urokinase and DNase can improve pleural adhesions.