负压封闭引流治疗小鼠创面铜绿假单胞菌感染的效果及机制

Efficacy of vacuum sealing drainage in mice infected with Pseudomonas aeruginosa and its mechanism

目的观察VSD对感染创面中铜绿似单胞菌生长的影响，并探讨其可能机制。方法选取健康成年雄性C57 BL／6小鼠40只，按照随机数字表法分为对照组和治疗组，每组20只。无菌条件下切除各小鼠背部1cm×1cm的全层皮肤，将细菌荧光素酶目的基因luxCDABE标记的野生型铡绿假单胞菌菌株PA01-lux涂抹于创面，包扎创而24h，制成铜绿假单胞菌感染小鼠模型，治疗组小鼠创向行VSD治疗（负压为-16．625kPa），对照组创面常规换药。分别于治疗前和治疗24h时，刚小动物活体成像系统检测2组小鼠创面PAOI-lux荧光强度，激光多普勒血流成像仪检测创面血流链，以实时荧光定量RT—PCR检测创缘组织IL-1β、血管内皮生长岗子（VEGF）的mRNA表达水平。观察治疗24h时2组小鼠创缘组织病理学特点。对实验数据行t检验。结果（1）治疗前，治疗纰小鼠创面PAOI-lux荧光强度与对照组相近（t=0．03，P=0．98）；治疗24h时，治疗绀的荧光强度为（2．69±0.75）光子·秒-1·厘米·单位角度。（photons·s-1·m-2·sr-1），明显低于对照组的（5．18±0．96）Dhotons．s-1·cm-2·sr-1 t=3．54，P=0．02。（2）治疗前，治疗组小鼠创面血流董与对照组相似（t=0．50，P=0．64）；治疗24h时，治疗组创面血流量为（96±9）灌注单位，明娃高于对照组的（70±11）灌注单位，t=3．13，P=0．04。（3）治疗前，2组小鼠创缘皮肤组织中IL-1β、VEGFmRNA表达水平接近（t=0．19，P=0．86；t=0．07，P=0．95）；治疗24h时，治疗组IL-1β、VEGF mRNA表达水平分别为4．72±0．37、2．68±0．39，均明显高于对照绀的2．24±0．50、1．22±0．13，t值分别为6．90、6．12，P值均为0．00。（4）治疗24h时，治疗组创缘皮肤组织内炎性细胞浸涧数量较对照绀增加约77％。结论与常规换药相比，VSD治疗在小鼠全层皮肤缺损早期即能明显降低创面铜绿假单胞菌含量。其机制叮能与增加创面局部血流量、提高创面组织炎性细胞数龟、促进IL-1β和VEGF的tuRNA表达有关。

Objective To observe the effect of vacuum sealing drainage （VSD） on the proliferation of Pseudomonas aeruginosa （PA） in infected wound, and to explore its possible mechanism. Methods Full-thickness skin wounds each with area of 1cm ×1cm were produced on the back of 40 C57BL/6 mice, and then they were contaminated with wild type PA strains PAO1 marked with target gene of hac.terial luciferase IuxCDABE （PAOI-lux）, they were dressed for 24 hours to reproduce PA infection model. Then mice were divided into experiment ~ E, with treatment of VSD （ pressure value at - 16. 625 kPa） ] and cuntrol （C, with treatment of conventional dressing change） groups according to the random number table, with 20 mice in each group. The fluorescence intensity of PAO1-lux and blood fluw in wound was respectively measured by in vivo optical imaging system and laser Doppler perfusion imagcr before treatment and at post treatment hour （ PTH ） 24. The expression levels of IL-1β and vasc.ular endothelial growth factor （VEGF） mRNA in wound edge were determited by real-time fluorescence quantitative RT-PCR befure treatment and at PTH 24. The specimens of wound edge tissue were collected for observation of pathological c.hange at PTH 24. Data were processed with t test. Results There were no obvious difference in fluorescence intensity of PAO1 -lux and blood tlow in wound between E and C groups befnre treatment （ with t value respectively 0.03,0. 50, P values all above 0.05 ）. The fluorescence intensity of PAOl-lux and blood flow in wound in E group at PTH 24 [ （2.69 ± 0.75 ） photons · s-1 . cm-2 · sr-land （96 ± 9） PU ] was respectively lower and higher than that in C group [ （5.18 ±0.96） photons ·s-1 · cm-2 · sr-1 and （70 ± 11） PU, with t value respectively 3.54, 3.13, P values all below 0. 05 ]. The expression levels of IL-1β and VEGF mRNA in both groups before treatment were similar （with t value respectively 0.19, 0. 07, P values all above 0. 05）. The expression levels of IL-1β and VEGF mRNA in E group at PTH 24 was respectively 4.72 ± 0.37, 2.68±0. 39, all markedly higher than those in C group （2.24 ± 0.50, 1.22 ± 0. 13, with t value respectively 6.90, 6.12, P values all equal to 0.00）. The number of inflammatory cell infiltrating the wound edge in E group at PTH 24 was increased by nearly 77% as compared with that in C group. Conclusions Compared with conventional dressing change, VSD can reduce the amount of Pseudomonas aeruginosa in full-thickness skin defect wound at the early stage, it may be related with an increase in blood flow and number of inflammatory cells in wound tissue, promoting expression of IL-1β and VEGF mRNA.