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Luminal bacteria and small-intestinal permeability
S M Riordan1, C J McIver, D H Thomas
1Dept. of Gastroenterology, Prince of Wales Hospital, Sydney, Australia.
Scandinavian Journal of Gastroenterology
|June 1, 1997
Summary
Small intestinal bacterial overgrowth (SIBO) with colonic-type bacteria increases small-intestinal permeability, independent of age or vitamin B12 levels. This functional disturbance is often missed by standard histology.
Area of Science:
- Gastroenterology
- Microbiology
- Human Physiology
Background:
- The impact of gut bacteria on small intestinal permeability is not fully understood.
- This study investigates the relationship between small intestinal bacterial overgrowth (SIBO) and small intestinal permeability.
Purpose of the Study:
- To assess the influence of luminal bacteria on small-intestinal permeability.
- To investigate the role of SIBO with colonic-type flora in altering small intestinal barrier function.
Main Methods:
- Investigated 34 subjects for SIBO using small intestinal aspirate culture.
- Performed lactulose/mannitol small intestinal permeability tests and assessed histology.
- Measured serum vitamin B12 and compared permeability in SIBO patients versus 34 controls.
Main Results:
- Increased urinary lactulose/mannitol ratios observed in SIBO patients with colonic-type flora (P < 0.0005).
- Elevated lactulose levels, not reduced mannitol, drove the increased permeability.
- Increased CD8+ intraepithelial lymphocytes noted, but not directly correlated with permeability severity.
Conclusions:
- Small intestinal permeability is elevated in SIBO with colonic-type bacteria, irrespective of age or vitamin B12 status.
- Increased CD8+ lymphocytes are present but unlikely to be the primary cause of permeability changes.
- Standard light microscopy may underestimate functional small intestinal disturbances in SIBO.