TRANSLOCATING BACTERIA: ROLE IN POSTSURGICAL SEPSIS

尽管最近在抗菌治疗方面取得了进展， 包括术后脓毒症在内的败血症患者， 百分之五十 最近的研究报道，全身性革兰氏阴性脓毒症 复发性腹腔内感染可能源于患者的 正常胃肠道植物群。 必须确定机制 因此细菌通常被包含在其中，但有时会逃逸 （移位）肠道并引起全身性疾病。 我们知道 在500种肠道菌中， 频率，但这些细菌是最常见的病原体 菌血症和术后脓毒症（E.大肠杆菌，肠球菌，葡萄球菌， Candida）。 在几种动物模型中，易位细菌可能是最常见的。 在肠系膜淋巴结中可靠地检测到，并且易位增加 在肠道植物群改变后或免疫抑制后 包括创伤和烧伤在内的侮辱。 我们已经定义了模型， 肠道细菌移位进入肠系膜淋巴结或进入 在正常大鼠中开始的实验性腹内脓肿。 惰性 颗粒如铁蛋白、淀粉和乳胶珠也可易位。 我们 有两个目的：（1）确定细菌或惰性物质 颗粒离开肠腔并进入肠系膜淋巴结，或 腹膜炎性渗出物;（2）确定 细菌被控制住了。 最初的实验将在 惰性粒子，因为这样的实验在技术上更容易。 我们可以 然后将详细的机理研究集中在用活细菌进行的实验上。 我们的方法包括进料荧光素标记的惰性颗粒， 细菌（活的和死的）和跟踪粒子迁移的路线 使用：（a）荧光扫描仪，一种粗略测量存在的仪器 组织中低浓度的荧光颗粒，使我们能够 大体确定肠组织的最相关病灶，（B）a流 细胞计数器，一种对不同细胞类型进行分类并测量 给定细胞类型内的荧光颗粒的数量;（c）传统的 对正常无菌场所的活菌进行定量的技术; 和（d）易位颗粒的光学和电子显微镜。 我们 目前的假设是，肠道细菌通常被运送到 吞噬细胞无法杀死它们， 只有当局部或全身因素损害细胞免疫时。 未能 杀死捕获的微生物，使它们能够局部扩散到炎症 病灶或体循环。

Despite recent advances in antimicrobial therapy, the mortality associated with bactermia, including postsurgical sepsis, remains between 25% and 50%. Recent studies have reported that both systemic gram-negative sepsis and recurrent intra-abdominal infections can originate from the patient's normal gastrointestinal flora. It is important to define the mechanism(s) whereby bacteria are normally contained within and yet some time escape (translocate) the intestinal tract and cause systemic disease. We know that relatively few of the 500 enteric species translocate with any frequency, but that these bacteria are the most frequent etiologic agents of bacteremia and postsurgical sepsis (E. coli, enterococci, staphylococci, Candida). In several animal models, translocating bacteria can be most reliably detected in mesenteric lymph nodes, and translocation is increased either after a shift in the intestinal flora or after immunosuppressive insults including trauma and burns. We have defined models whereby intestinal bacteria translocate either into mesenteric lymph nodes or into experimental intra-abdominal absesses initiated in normal rats. Inert particles such as ferritin, starch, and latex beads also translocate. We have two aims: (1) to determine the route(s) by which bacteria or inert particles leave the enteric lumen and pass into mesenteric lymph nodes or peritoneal inflammatory exudates; and (2) to determine the means by which the bacteria are contained. Initial experiments will be performed with inert particles because such experiments are technically easier. We can then focus detailed mechanistic studies on experiments with live bacteria. Our method includes feeding fluorescein labeled inert particles and bacteria (live and dead) and tracking the route of particle migration using: (a) a FLUOROSCAN, an instrument that grossly measure the presence of low concentrations of fluorescent particles in tissue and allows us to grossly determine the most relevant foci of intestinal tissue, (b) a flow cytometer, an instrument that sorts different cell types and measures the number of fluorescent particles within a given cell type; (c) traditional techniques of quantitation of viable bacteria in normally sterile sites; and (d) light and electron microscopy of translocating particles. Our working hypothesis is that intestinal bacteria are normally transported out of the intestinal lumen within phagocytic cells which fail to kill them only when local or systemic factors impair cellular immunity. Failure to kill the entrapped microbes permit them to spread locally to inflammatory foci or to the systemic circulation.