Current status of bacterial translocation as a cause of surgical sepsis

In recent years it has been increasingly recognized that the gastrointestinal tract has functions other than simply the digestion and excretion of foodstuffs. The gut is also a metabolic and immunological organ that serves as a barrier against living organisms and antigens within its lumen. This role is termed ‘gut barrier function’. The fact that luminal contents in the caecum have a bacterial concentration of the order of 10 organisms per millilitre of faeces, whilst portal blood and mesenteric lymph nodes are usually sterile, dramatically illustrates the efficacy of this barrier function. The idea that the alimentary tract, teeming with its own bacterial flora, could represent a source of sepsis under certain conditions has interested clinicians for many years. This theory, usually referred to as the ‘gut origin of sepsis’ hypothesis, is not new. In the late nineteenth century, the idea developed that peritonitis could result from the passage of bacteria from organs adjacent to the peritoneal cavity. In Germany this was referred to as durchwanderungs-peritonitis, literally translated as ‘wandering through peritonitis’. In 1891 and 1895, two separate investigators hypothesized that viable bacteria could pass through the intact gut wall in vivo. These findings were confirmed after the Second World War by Fine and colleagues who were able to detect viable bacteria in the peritoneal cavity of dogs in a haemorrhagic shock model. Schatten et al. demonstrated that bacteria could migrate from the gastrointestinal tract into the portal circulation in the absence of an infective process in humans. Subsequently it has become clear that, in addition to Gram-negative bacteria, endotoxin, Gram-positive bacteria and fungi can pass through the mucosal barrier. In 1979, Berg and Garlington defined this phenomenon as ‘bacterial translocation’. The term ‘bacterial translocation’ is used to describe the passage of viable resident bacteria from the gastrointestinal tract to normally sterile tissues such as the mesenteric lymph nodes and other internal organs. The term also applies to the passage of inert particles and other macromolecules, such as lipopolysaccharide endotoxin, across the intestinal mucosal barrier. Accepted: November 1, 2004