Available data document that translocation of enteric microbes is a normal process, occurring at low background levels in normal humans and in laboratory animals, and increasing in certain clinical conditions. There is likely no one common mechanism facilitating systemic infection with enteric flora; rather, systemic infection depends on the extent to which the host experiences enteric overgrowth, increased intestinal permeability, and/or immunosuppression. Thus, systemic infection results from these three factors, acting alone or in concert, to overwhelm the host's ability to eliminate translocating microbes. Although the existence of microbial translocation is well documented in humans and experimental animals, the clinical significance of this phenomenon has been the subject of intense debate. Data from recent clinical studies support the hypothesis that the translocation of enteric flora is clinically significant and predisposes to infectious complications, possibly including multiple organ failure. (C) 2000 Lippincott Williams and Wilkins, Inc.