摘要:It is still uncertain whether upper gastrointestinal bacterial overgrowth in patients with permanent achlorhydria causes malassimilation in more than just the occasional case. In an attempt to clarify this, 19 patients with pernicious anaemia who had undergone a thorough investigation 6.6 y (mean) previously, were reinvestigated with clinical history, upper GI endoscopy including multiple duodenal biopsies, microbial cultures of gastric juice and duodenal mucosa, a xylose absorption test, and estimation of duodenal disaccharidase activity. At the present examination 58 per cent of the patients had mild abdominal symptoms. Mean Broca's index was 98.4 per cent. Eight of 19 patients had mild or moderate histological duodenitis. Faecal-type bacteria were found in gastric juice and/or duodenal mucosa in 10/19 cases. Xylose absorption was impaired in three patients. Low duodenal lactase activity was found in four patients, one of whom also showed low sucrase and maltase activities. No significant correlations were found among the variables: clinical symptoms, histological, microbiological and biochemical findings. In this consecutive group of patients with pernicious anaemia malassimilation of major clinical significance was rare despite frequent upper gastrointestinal colonisation with faecal-type bacteria.Keywords: Bacterial overgrowth; Disaccharidases; Malassimilation; Pernicious anaemia; Xylose absorption test.