TRANSLOCATING BACTERIA: ROLE IN POSTSURGICAL SEPSIS

尽管最近在抗菌治疗方面取得了进展，但与 细菌症，包括术后脓毒症，保持在25%到 50%。最近的研究报道，系统性革兰氏阴性脓毒症 而反复发生的腹内感染可能源于患者的 正常的胃肠道菌群。重要的是要明确机制(S) 细菌通常被控制在体内，但有时又会逃脱 (移位)肠道并引起全身疾病。我们知道 在500种肠道物种中，相对较少的物种与 但这些细菌是最常见的病原体 菌血症和术后败血症(大肠杆菌、肠球菌、葡萄球菌、 假丝酵母)。在几种动物模型中，细菌移位可能是最 在肠系膜淋巴结中可靠检测到，移位增加 在肠道菌群改变或免疫抑制后 侮辱包括创伤和烧伤。我们定义了模型，通过这些模型 肠道细菌要么转移到肠系膜淋巴结，要么转移到 正常大鼠的实验性腹内失血。惰性 铁蛋白、淀粉和乳胶珠等颗粒也会转移。我们 有两个目的：(1)确定(S)细菌或惰性物质的路线 颗粒离开肠腔，进入肠系膜淋巴结或 腹腔炎性渗出物；以及(2)确定 细菌被控制住了。初步实验将在以下情况下进行 惰性粒子，因为这样的实验在技术上更容易。我们可以的 然后将详细的机理研究集中在用活细菌进行的实验上。 我们的方法包括喂食荧光素标记的惰性颗粒和 细菌(活的和死的)和追踪颗粒迁移的路线 使用：(A)荧光扫描仪，这是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 大体上确定肠道组织最相关的病灶，(B)流动 细胞仪，这是一种对不同类型的细胞进行分类并测量 特定细胞类型内的荧光颗粒数量；(C)传统 通常无菌场所中活细菌的定量技术； 以及(D)转移颗粒的光学和电子显微镜。我们的 工作假说是肠道细菌通常被运输出去 吞噬细胞内的肠腔，吞噬细胞无法杀死它们 只有在局部或全身因素损害细胞免疫的情况下。未能做到 杀死被困住的微生物允许它们在局部传播到炎症 病灶或对体循环的影响。

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.