小型猪耐甲氧西林金黄色葡萄球菌感染创面模型的建立

Reproduction of a model of methicillin-resistant Staphylococcus aureus infected skin wound in minipig

目的：建立耐药菌感染创面模型，为研究抗菌药物提供可靠稳定的动物模型。方法：在3～4个月龄小型猪背部脊柱中线旁开4cm处用直径16mm的切割器每侧钻出6个至深筋膜的圆形切口，创面间隔3cm。将创面随机分为两组，一侧为耐甲氧西林金黄色葡萄球菌（MRSA）感染组，于创面形成后30min接种MRSA菌液0．1ml（1×10^8CFU／cm^2）；对侧为对照组，接种等体积生理盐水。伤后不同时间进行创面炎症反应及愈合的大体观察和组织学观察，测量创面面积，进行组织细菌学检测。结果：MRSA感染2d后创面暗红、创缘肿胀、渗出多、有大量白色分泌物且愈合慢；感染后2、10d创面组织培养菌落数均超过1×10^8CFU／g；对照组2d和10d组织培养菌落数为1×10^5CFU／g，不足以影响伤口正常愈合。组织学观察显示感染后2、10d，MRSA感染组较阴性对照组炎症细胞明显增多、肉芽组织生长缓慢。对照组新生肉芽生长较快，有大量新生血管生成。结论：采用小型猪背部2cm。的全层皮肤缺损创面接种1×108cFu／cm。MRSA的方法，2d后可以形成MRSA感染创面，且具有创面面积可控、感染效果稳定的优点。

Objective： To reproduce an animal skin wound model with controllable area of infection of drug- resistant bacteria, in order to provide a reliable and stable animal model for study of treatment of wounds infected by drug-resistance bacteria. Methods： Twelve round full thickness skin defect wounds with a diameter of 16 mm （area was 2 cm2） were reproduced on the back of minipigs of 3-4 months old, with 6 wounds on each side of the spine 4 cm away from spine. All of skin wounds were divided into two groups： wounds on one side of the spine were designated as the methicillin- resistant Staphylococcus aureus （MRSA） infection group, and they were inoculated with MRSA containing fluid 0.1 ml （1× 10^8 CFU/cm2） 30 minutes after injury; the wounds on the other side of the spine served as control group, and they were inoculated with the same volume of normal saline. The changes in inflammatory reaction and healing of the wounds were observed at different times after injury, while area of the wounds was measured, and bacteria culture and pathological observation were carried out. Results： The wounds appeared dull red, with swollen wound margin, and large amount of white exudation were found 2 days after MRSA inoculation. The bacteriological findings indicated that MRSA infection persisted, with colony count of the wound tissue higher than 1 × 108 CFU/g 2 and 10 days after infection, while the colony count of bacteria was 1 × 105 CFU/g in the control group, without obvious effect on the healing of the wound. The pathological examination showed that there were larger amount of inflammatory cells in MRSA infection group than in the control group on day 2 and 10, while the growth of granulation tissue was slower significantly in MRSA infection group than that in the control group. There were a large number of new vessels in the control group with faster growth of granulation tissue. Conclusions： The infected wound model can be successfully reproduced 2 days after inoculating 1 × 10^8 CFU/cm2 MRSA into full thickness skin defect wounds on the back of minipig with controllable wound area and stable result.