We compared the diagnostic accuracy of microscopical examination of multiple faecal specimens with duodenal juice examination in the diagnosis of giardiasis. Of 292 patients who had stool microscopy and duodenal aspirate, Giardia were identified in either stools or duodenal fluid from 73 patients (25%). Giardiasis was diagnosed in 62 (73%) with the first faecal specimen, but examination of 3 specimens increased the diagnostic yield to 85%. Giardia, however, were found in only 32 of 73 duodenal aspirates examined (44%). This finding is contrary to the widely held belief that duodenal fluid examination is superior to stool microscopy for the diagnosis of giardiasis. The 2 approaches are complementary, however, since Giardia was found in duodenal fluid, only, from 15% of patients.
D-Xylose transport in the human jejunum was studied in vivo using a standard intestinal perfusion technique, and also in vitro in human jejunal brush border membrane vesicles. Initial D-xylose concentrations were linearly related to D-xylose absorption rates, a finding consistent with passive diffusion. Perfusion of D-xylose with varying D-glucose concentrations were aimed at examining D-xylose-D-glucose jejunal cotransport. D-Xylose absorption rates from a 30 mM D-xylose perfusate did not change significantly when 10, 30, or 60 mM glucose were added (-3.0 +/- 0.62 vs -3.34 +/- 0.71, -3.82 +/- 0.81, and -4.56 +/- 0.72 mM/30 cm/hr, respectively; minus indicates net absorption) suggesting an absence of a cotransport system. In brush border membrane vesicles, xylose uptake was partially inhibited by D-glucose and phlorizin. These data suggest that jejunal D-xylose absorption, at concentrations used clinically, is by passive diffusion, which process completely overrides a minor D-glucose cotransport component. The D-xylose tolerance test, therefore, reflects jejunal mucosal surface area and mucosal permeability to D-xylose and not nutrient carbohydrate absorption.
Faecal microscopical diagnosis of Strongyloides and hookworm infections is insensitive. We have therefore compared duodenal fluid and faecal microscopy for detection of these parasites in a group of 292 patients being investigated for gastrointestinal symptoms who were examined by both techniques. Thirty-three of these patients (8%) were infected with Strongyloides stercoralis and 88 (30%) had hookworm infections. Microscopical examination of up to 3 faecal specimens detected only 33% and 65% of patients with Strongyloides and hookworm infections, respectively. Microscopical examination of a single specimen of duodenal fluid was more sensitive for detection of strongyloidiasis, identifying 76% of patients; the parasite was found exclusively in duodenal fluid (and not in faeces) in 67% of patients. For hookworm, the diagnostic sensitivity was similar with both techniques but duodenal fluid microscopy detected some patients (35%) who had not been identified by faecal microscopy. This study confirms previous work indicating the insensitivity of faecal microscopy in these infections and emphasizes the need to consider routine examination of duodenal fluid to exclude chronic strongyloidiasis. This may have particular relevance for south-east Asian war veterans and immunocompromised patients.
Bicarbonate, citrate, or acetate are commonly included in oral rehydration solutions to correct acidosis and possibly because of their ability to promote water and sodium absorption. We have investigated the effect of these anions on water and sodium transport in normal and also in secreting (cholera toxin-treated) rat small intestine using a single-pass perfusion technique. In normal jejunum bicarbonate and acetate produced net absorption, and citrate net secretion of both water and sodium. In normal ileum all anions produced net absorption of water and sodium. In the secreting jejunum, however, bicarbonate had no effect on water and sodium secretion, whereas acetate and citrate actually enhanced the secretory state for both water and sodium. None of these anions had any effect on water and sodium secretion in the ileum. These observations suggest that normal and secreting intestine are qualitatively different with regard to handling of these organic anions. The addition, therefore, of bicarbonate, acetate, or citrate to oral rehydration solutions may have no beneficial effect with regard to the promotion of water and sodium absorption in the secreting intestine during acute diarrhoeal states and could actually be deleterious.
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