烧烫伤创面感染的小鼠模型构建

Establishment of a mouse model of burn wound infection

目的探讨一种简单、稳定的烧烫伤创面感染的小鼠模型构建方法,以便进行相关烧烫伤创面修复研究。方法取30只BALB/c小鼠,采用自制木质烫伤板,沸水浴法烫取直径8 mm的圆形创面,烫伤时间分别为5 s、10 s、15 s。伤后48 h,取创面组织进行HE染色观察,筛选最佳创面烫伤时间。另取72只小鼠制成深Ⅱ度烫伤创面,采用擦刮法分别接种20μL菌浓度为1×106、l×107、1×108CFU/mL金黄色葡萄球菌标准菌株ATCC 25923的菌液。接种细菌后72 h,取创面组织HE染色观察创面炎症反应情况,并测定3、7、14 d的皮肤菌负荷,筛选最佳的细菌接种浓度。最后,按最佳条件建模后,观察创面的完全愈合时间以及创面愈中、愈后的组织学变化,以确定此创面感染模型是否建立成功。结果组织学结果表明,10 s为深Ⅱ度创面的理想致伤时间,最佳接种菌浓度为l×108CFU/mL,此时期,14 d内菌负荷均高于l×105CFU/g。该模型的创面愈合时间(21±0.95 d)较正常创面愈合时间(15.92±0.34 d)明显延长(P<0.01),炎性反应明显,愈后不佳。结论烧烫伤创面感染的小鼠模型构建成功,可作为感染创面防治研究的实验动物模型。

Objective To establish a simple mouse model of burn wound infection and provide useful tool for studies of prevention and treatment of burn wound infection. Method Self-made wood burn board and boiling water was used to generate burn injury （ in a diameter of 8 mm） on both sides of the back in 30 BALB/C mice for different duration （5 s, 10 s, 15 s, with 10 mice in each group）. 48 h post-burn, the wounds were examined by histology to determine the depth of injury. Deep Ⅱ degree scald on the back in other 72 mice was generated. Immediately after the burning,20 μL of bacterial suspension containing 1 × 10^6 , 1 × 107 or 1 × 10^8 CFU/mL Staphylococcus aureus ATCC 25923 was inoculated to the wounds by scraping, respectively （24 mice for each group）. Inflammatory reaction of the wounds was examined with HE staining at 72 h post inoculation for screening the best bacteria inoculation concentration. On day 3, 7 and 14 post inoculation, the amount of wound bacterial load was assayed, respectively. Finally, the best condition was chosen to establish animal models. The time of wound healing was recorded and pathological examination with HE staining was done at the 7th and 14th days after injury to determine whether the wound infection model was established successfully. Results Burning for 10 s was determined as injury time resulting in deep II degree scald, and according to histological examination 1 × 10^8 CFU/mL was chosen as best bacteria inoculation concentration. The bacteria isolated from the wounds were identified as Staphylococcus aureus. The subescbar bacteria count on day 14 post-burn was more than 1 × 10^5 CFU/g of tissue. Compared with the control group, the infected group showed a longer time of wound healing （21 ± 0. 95 d）, significantly longer than that of the control group （ 15.92±0. 34 d, P 〈0.01 ）. Obvious inflammatory response was observed with poor outcome of the mice. Conclusion A mouse model of burn wound infection is successfully established, which may serve as a reliable model for studies of burn wound infection.