Morphometric study of the small bowel mucosa in infants with diarrhea due to enteropathogenic Escherichia coli strains.

BACKGROUND/AIMS: Enteropathogenic Escherichia coli (EPEC) strains are the most important cause of gastroenteritis in infants under 1 year of age and may induce several patterns of villous atrophy in the intestinal mucosa. However, the interpretation of these abnormalities has usually been based on semiquantitative criteria, giving rise to considerably subjective results. We utilized the linear morphometry to analyze the morphological lesions of the small bowel mucosa induced by EPEC strains in infants with persistent diarrhea in comparison with those seen in infants with asymptomatic environmental enteropathy (AEE) and controls.

METHODOLOGY

Fifty nine specimens of small bowel mucosa were comparatively studied and divided in the following groups: 1. Group I: Thirty infants with persistent diarrhea due to EPEC strains, mean age 6.4 months; 2. Group II: Sixteen infants with AEE, mean age 6.5 months with no enteropathogenic bacteria in stools; 3. Group III: Thirteen children with short stature and no gastrointestinal complaints, mean age 15 months. Morphometric analysis of the small bowel mucosa was performed by using a x10 objective to a Zeiss light microscope, to which a measuring Zeiss ocular, t8x was adapted. The following measurements were carried out: Total mucosal thickness (TMT); Villous height (VH); Crypt length (CL); Intraepithelial lymphocyte (IEL) count.

RESULTS

Except for the IEL, there was a significant difference in all the parameters analyzed among the evaluated groups. Group I revealed the lowest values for total mucosal thickness, villous height, and the ratio villous height/crypt length in comparison with the two other groups. On the other hand, the crypt length measurements for Group II were larger than those for Groups I and III. The measurements of villous height and the ratio villous height/crypt length for Group III turned out to be greater than those for Group II.

CONCLUSIONS

The utilization of an accurate technique in the morphological study of the small bowel mucosa allowed us to detect severe abnormalities not only in infants with EPEC infection, but also in those counterparts who live in contaminated environments, and can therefore potentially acquire this type of intestinal infection.