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Studies of the small bowel surface by scanning electron microscopy in infants with persistent diarrhea
U Fagundes-Neto1, S De Martini-Costa, M Z Pedroso
1Divisão de Gastroenterologia Pediátrica, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
Insights
Persistent diarrhea in infants is linked to small bowel surface abnormalities and bacterial overgrowth. Scanning electron microscopy revealed villus stunting, enterocyte damage, and microvilli loss in all affected infants.
Area of Science:
- Pediatric Gastroenterology
- Microbiology
- Cell Biology
Background:
- Persistent diarrhea in infants is a significant clinical challenge.
- Understanding the underlying pathophysiology is crucial for effective treatment.
Purpose of the Study:
- To investigate the ultrastructural abnormalities of the small bowel surface in infants with persistent diarrhea.
- To correlate these findings with bacterial overgrowth and enteropathogenic agents.
Main Methods:
- Scanning electron microscopy (SEM) of small bowel biopsies from 16 infants.
- Analysis of jejunal secretions for bacterial overgrowth (colony counts > 10(4) colonies/ml).
- Stool cultures for enteropathogenic agents.
Main Results:
- All 16 infants exhibited morphological abnormalities in the small bowel mucosa, ranging from moderate to severe.
- SEM revealed villus stunting, subtotal villus atrophy, deranged enterocytes, decreased/absent microvilli, and mucus-fibrinoid pseudomembranes in half the patients.
- Bacterial overgrowth was present in 68.7% of patients, and enteropathogenic agents were identified in 50%.
Conclusions:
- Persistent diarrhea in infants is associated with significant small bowel mucosal damage.
- Ultrastructural changes, including villus atrophy and enterocyte alterations, are consistently observed.
- Bacterial overgrowth and enteropathogenic infections likely contribute to the observed pathology and persistent diarrhea.
Abstract:
We describe the ultrastructural abnormalities of the small bowel surface in 16 infants with persistent diarrhea. The age range of the patients was 2 to 10 months, mean 4.8 months. All patients had diarrhea lasting 14 or more days. Bacterial overgrowth of the colonic microflora in the jejunal secretion, at concentrations above 10(4) colonies/ml, was present in 11 (68.7%) patients. The stool culture was positive for an enteropathogenic agent in 8 (50.0%) patients: for EPEC O111 in 2, EPEC O119 in 1, EAEC in 1, and Shigella flexneri in 1; mixed infections due to EPEC O111 and EAEC in 1 patient, EPEC O119 and EAEC in 1 and EPEC O55, EPEC O111, EAEC and Shigella sonnei in 1. Morphological abnormalities in the small bowel mucosa were observed in all 16 patients, varying in intensity from moderate 9 (56.3%) to severe 7 (43.7%). The scanning electron microscopic study of small bowel biopsies from these subjects showed several surface abnormalities. At low magnification (100X) most of the villi showed mild to moderate stunting, but on several occasions there was subtotal villus atrophy. At higher magnification (7,500X) photomicrographs showed derangement of the enterocytes; on several occasions the cell borders were not clearly defined and very often microvilli were decreased in number and height; in some areas there was a total disappearance of the microvilli. In half of the patients a mucus-fibrinoid pseudomembrane was seen partially coating the enterocytes, a finding that provides additional information on the pathophysiology of persistent diarrhea.