American Journal of Clinical Nutrition, Vol 23, 1588-1594, Copyright © 1970 by The American Society for Clinical Nutrition, Inc.

Effects of Lactulose and Lactobacillus acidophilus on the Fecal Flora

¹ From the Departments of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut and the Veterans Administration Hospital, West Haven, Connecticut

Portal—systemic encephalopathy (PSE) is generally considered to be a consequence of bacterial enzymatic activity on nitrogenous substrates in the intestinal tract. The introduction of lactulose and of Lactobacillus acidophilus therapy was based on the assumption that replacement of proteolytic bacteria by fermentative organisms would improve PSE. Previous studies have shown that the fecal flora in cirrhotic patients with PSE is qualitatively and quantitatively similar to that of normal subjects and cirrhotic patients without PSE. The present studies demonstrate that lactulose did not significantly affect the fecal floral pattern in either normal subjects or cirrhotic patients. Furthermore, changes in the total number of lactobacilli in individual patients did not correlate with results of therapy. Similarly, there were no significant changes in the stool pattern after L. acidophilus therapy, except for a decrease in total anaerobic bacteria, and no apparent correlation with the clinical response.

The lack of change may indicate that current cultural methods are too insensitive to detect physiologically important alterations, that the fecal floral pattern does not accurately reflect the intestinal pattern, or that the quantitative stool bacterial pattern is not critical in the pathogenesis of PSE.