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Proposed mechanisms for the translocation of intestinal bacteria
C L Wells1, M A Maddaus, R L Simmons
1Department of Surgery, University of Minnesota, Minneapolis 55455.
Abstract:
Members of the endogenous flora have become recognized as major pathogens in nosocomial infections, and the intestinal tract has become recognized as a major portal of entry for these pathogens. The English-language literature on this topic has been summarized and a working hypothesis devised describing a mechanism whereby intestinal bacteria can escape and cause systemic disease. It is postulated that the motile phagocyte ingests intestinal bacteria, transports them to extraintestinal sites, fails to accomplish intracellular killing, and then liberates the bacteria in the extraintestinal site. This hypothesis is consistent with many observations found in the literature: (1) The intestinal bacteria that most readily translocate out of the intestinal tract are classified as facultative intracellular pathogens. (2) Intestinal particles with no intrinsic motility (e.g., yeast, ferritin, starch) can translocate out of the intestinal lumen within hours after their ingestion. (3) The rate of translocation of intestinal bacteria can be altered with agents that modulate immune (including phagocytic) function. In the context of the mechanisms involved in intestinal immune responses, bacterial translocation appears to be a part of the normal antigen-sampling process of gut-associated lymphoid tissue. Systemic disease caused by translocating intestinal bacteria could be due to a maladaptation of the antigen-sampling process that has been designed to regulate the immune response to intestinal antigens.
Insights
Intestinal bacteria can cause systemic infections when immune cells transport them to other body sites. This bacterial translocation may stem from a malfunction in the gut
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Endogenous flora are increasingly recognized as significant pathogens in hospital-acquired infections.
- The intestinal tract serves as a primary entry point for these pathogens into the body.
- Understanding the mechanisms of bacterial translocation is crucial for preventing nosocomial infections.
Purpose of the Study:
- To propose a working hypothesis for the mechanism of bacterial translocation from the intestinal tract.
- To explain how intestinal bacteria can escape the gut and cause systemic disease.
- To correlate bacterial translocation with immune function and antigen sampling.
Main Methods:
- Literature review and synthesis of English-language studies on bacterial translocation.
- Development of a hypothesis based on existing observations.
- Analysis of factors influencing bacterial translocation, including immune modulation.
Main Results:
- Facultative intracellular pathogens are the most common bacteria to translocate from the gut.
- Non-motile intestinal particles can also translocate rapidly after ingestion.
- Immune function modulation affects the rate of bacterial translocation.
Conclusions:
- Bacterial translocation is potentially linked to the normal antigen-sampling process of gut-associated lymphoid tissue.
- Systemic infections may arise from a maladaptation of this immune surveillance mechanism.
- The hypothesis provides a framework for understanding how gut bacteria can lead to extraintestinal infections.