Alterations of Small Intestinal Microflora after Chronic Alcohol Abuse

Background:Functional and morphological changes of small intestinal mucosa are well recognized following chronic alcohol abuse,but the changes of intraluminal environment and microflora are not yet clear.Aims:To investigate the alterations of the small intestinal microflora after chronic alcohol abuse.Methods:Thirt y-two Wistar rats were divided randomly into 4 groups:control,chronic alcohol,chronic alcohol withdrawal and acute alcohol groups(each group composed of 8 rats).The rats in chronic alcohol group drank 25% alcohol for 6 months;the rats in chronic alcohol withdrawal group were given 25% alcohol for 6 months,then withdrew for another 6 months;the rats of acute alcohol group received 7.5 g alcohol/kg per day by intragastric administration of 25% alcohol for 3 days.Intestinal mucosal samples were used for aerobic and anaerobic culture.Bacteria in the mucosa were isolated and quantified.Results:Aerobic bacteria in the intestinal mucosa in chronic alcohol group increased to 10 folds higher than that in the control group,predominantly the enterococcus,streptococcus and staphylococcus epidermis,with a decrease in the absolute number of lactobacillus.The ratio of lactobacillus to aerobic bacteria declined 38%.Lactobacillus in chronic alcohol withdrawal group increased to several thousand folds when compared with that in the chronic alcohol group,and the ratio of lactobacillus to aerobic bacteria returned to the value of control group.Inflammatory lesions including bleeding and erosion in chronic alcohol group were milder than those in the acute alcohol group,and these lesions recovered after withdrawal of alcohol.Conclusions:Overgrowth of aerobic bacteria with decrease in lactobacillus in small intestine was observed in rats treated with long-term alcohol ingestion,and the decrease of lactobacillus may enhance the pathogenicity of intestinal bacteria.