Effects of lactulose on intestinal bacterial flora and fecal organic acids in patients with liver cirrhosis

To evaluate the effects of oral lactulose on fecal bacterial flora, we measured fecal bacterial counts and organic acid concentration before and 2 weeks after lactulose administration in patients with liver cirrhosis. Lactulose administration resulted in increases in the total anaerobic bacterial count and in the proportion of Bifidobacterium, and a decrease in that of Bacteroides in the flora. Fecal concentrations of organic acids remained unaltered following lactulose administration. These results suggest that lactulose administration suppresses the proportion of urease-forming bacteria independent of fecal organic acid levels. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.