![]() Clostridium difficile infection can often be identified endoscopically and histologically by its characteristic pseudomembrane formation ( Figure 4). ![]() The diagnosis can be confirmed by the detection of C difficile toxin in stool, and a subset of patients undergo sigmoidoscopy or colonoscopy with biopsy. The diagnosis should be suspected in anyone who develops diarrhea during a course of antibiotics or within 6–8 weeks of completing treatment. Clostridium difficile infection is a good example of the latter mechanism, as the toxins produced by the bacteria cause direct tissue damage. Although some pathogens damage the bowel through direct mucosal invasion, others produce toxins, which in turn cause tissue injury and symptoms. It remains elusive why individuals residing in the southern parts of the United States harbor greater numbers of eosinophils in their lamina propria.īacterial infections may affect the colon in a number of ways. ![]() 2 This review of 256 mucosal biopsies from patients without symptoms found that the mean number of eosinophils per intercryptal space was highest in the southern United States, a 35-fold difference between the mean eosinophil concentrations of patients in New Orleans compared with Boston. Another study examined the variability in colonic eosinophils depending upon where in the United States patients lived. One can conclude that intramucosal eosinophils are more numerous normally in the proximal colon, but show only mild fluctuations with ambient allergen exposure. Interestingly, mucosal eosinophils were slightly more numerous in samples obtained in April and May, corresponding to periods of highest pollen counts, but this relationship did not attain statistically significance. Lamina propria eosinophils were, on average, 3 times more numerous in the ascending relative to the descending colon. 1 Fifty-five percent of biopsies from the ascending colon contained eosinophils in the crypt epithelium, compared with only 5% of biopsy specimens from the descending colon. One study quantified the number of mucosal eosinophils regarded as a normal finding in the right and left colon in 198 colon mucosal biopsies from those with normal endoscopic exams. Eosinophils are a normal constituent in the lamina propria, and their quantity and distribution have been the source of several investigations.
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