Mechanisms of malabsorption in the "Contaminated Small-Bowel syndrome"

The mucosa of the upper small intestine in humans is repeatedly exposed to potentially harmful environmental influences: infective, toxic and antigenic. One of the most significant manifestations of the control over environmental risks is how the upper intestinal milieu is kept relatively sterile and pathogen-free despite constant exposure to a potentially hostile and pathogen-ridden environment. This control is lost in the so-called "Contaminated Small-Bowel Syndrome" when profuse numbers of bacteria contaminate the contents of the upper bowel. This can occur in a vast array of clinical situations ranging from infancy to old age. The consequences of upper intestinal bacterial overgrowth are very diverse. The mechanisms causing diarrhoea and malabsorption in this syndrome illustrate facets of pathophysiology of many inter-relating processes of intestinal digestion and absorption.