MRSA气溶胶诱导烫伤SKH-1无毛小鼠皮肤感染合并肺炎模型

目的 探讨烫伤条件下，建立MRSA气溶胶致SKH-1无毛小鼠皮肤感染合并肺炎模型的方法及其评价指标。方法 48只SKH-1无毛小鼠，随机分成PBS对照组，单纯感染组和烫伤合并感染组。合并感染组小鼠皮肤烫伤后，MRSA(ST-239)气溶胶呼吸道感染，采用体重、血常规、菌血症率、皮肤和脏器荷菌量、病理组织学变化和分子生物学等指标对模型进行综合评价。结果 与其他两组相比，合并感染组小鼠体重下降明显；白细胞数显著增多；菌血症率达100%；皮肤和肺荷菌量较高，分别达108CFU/g和106CFU/g；镜下观察皮肤和肺炎症病变明显；免疫组化结果显示皮肤组织内CD138呈阳性表达；multi-PCR测定感染组织内nuc和mecA基因均为阳性。结论 SKH-1无毛小鼠烫伤再辅以MRSA气雾攻击的方式，可成功建立能够模拟临床上烧烫伤患者继发MRSA肺炎的动物模型，此模型对于抗MRSA药物药效评价研究具有重要临床应用价值。

A scald SKH-1 hairless mouse model of skin infection with pneumonia induced by aerosolized MRSA

Objective To establish a SKH-1 hairless mouse model of skin and lung infection by methicillin-resistant Staphylococcus aureus(MRSA) aerosol and its evaluation system. Methods 48 SKH-1 hairless mice were randomly divided into PBS control group, infection group and infection with scald group. After the dorsal skin of the infection with scald group were thermally injured, mice were challenged with aerosolized MRSA(ST-239) through the respiratory tract, then the models were evaluated by body weight, blood tests, bacteraemia rate, skin and organs infection measuring, histopathological observations and multi-PCR for the nuc and mecA genes detection. Results Compared with the other two groups, the infection with scald group had evident weight loss, remarkable increase of WBC count and a bacteraemia rate of 100%. The number of viable S. aureus in the skin and lungs was 108CFU/g and 106CFU/g respectively, inflammatory lesions of the infected tissues were obvious under the light microscope. The results of immunohistochemistry showed that CD138 expressed positively in the skin, and positive results were also found with both nuc and mecA genes in the infected tissues of the infection with scald group. Conclusion We established a scald SKH-1 hairless mouse model, challenged with aerosolized MRSA, which can well simulate clinical burn patients with secondary infection of MRSA pneumonia. This mouse model is of important clinical application value for the evaluation of MRSA-related antimicrobial treatments.