Adhesion of bacteria to the human small-intestinal mucosa. A scanning electron microscopic study

During the period 1 January 1980 to 30 June 1986, a total of 543 small-intestinal biopsy specimens from adults with gastrointestinal symptoms were available for routine analysis with correlated scanning electron microscopy and light microscopy. Adhesion of microorganisms was found in 77 biopsy specimens. Microorganisms in 64 specimens were classified as bacteria, in 10 as microfungi and in 4 as protozoa, including 1 specimen with both bacteria and microfungi. The structural types of bacteria found were morphologically cocciform, 8; short rod-shaped, 14; and long rod-shaped, 43. One specimen demonstrated adhesion of two structural types of bacteria. Bacteria were found in specimens from all age groups in roughly equal frequency. There was no difference in villus structure when comparing specimens from the groups with and without adhering bacteria, whereas ultrastructural alteration--that is, thinning of glycocalyx layer--was significantly more frequent in the group with bacteria. Moreover, within the group of specimens with bacteria the presence of long rod-shaped bacteria was associated with both damage of villus structure and deviation of cell surface ultrastructure. An increased amount of neutrophil granulocytes as an indicator of acute inflammation was found in 6 of 51 specimens with bacterial adhesion but in none of a matched reference material. In contrast, the amount of plasma cells and lymphocytes in the lamina propria and the amount of intraepithelial lymphocytes did not differ.