Persistence of colonization of human colonic mucosa by a probiotic strain, Lactobacillus rhamnosus GG, after oral consumption

Abstract

Lactobacillus rhamnosus GG is one of the most thoroughly studied probiotic strains. Its advantages in the treatment of gastrointestinal disorders are well documented. The aim of the present study was to demonstrate with colonic biopsies the attachment of strain GG to human intestinal mucosae and the persistence of the attachment after discontinuation of GG administration. A whey drink fermented with strain GG was fed to human volunteers for 12 days. Fecal samples were collected before, during, and after consumption. L. rhamnosus GG-like colonies were detected in both fecal and colonic biopsy samples. Strain GG was identified by its characteristic colony morphology, a lactose fermentation test, and PCR. This study showed that strain GG was able to attach in vivo to colonic mucosae and, although the attachment was temporary, to remain for more than a week after discontinuation of GG administration. The results demonstrate that the study of fecal samples alone is not sufficient in evaluating colonization by a probiotic strain.

FIG. 1

Fecal counts of lactic acid bacteria (■) and L. rhamnosus GG-like colonies (▵). The solid line shows the mean counts of lactic acid bacteria, and the dashed line shows the mean counts of strain GG. In this context, lactic acid bacteria are defined as colonies growing on MRS agar without further taxonomic characterization, with the exception of GG-like colonies. The end of L. rhamnosus GG administration is marked by a vertical arrow below the horizontal axis.

FIG. 2

Detection of L. rhamnosus by PCR coupled with gel electrophoresis. Lanes: 1, molecular weight marker; 2 through 19, strain GG-like findings from fecal samples; 20, positive control (L. rhamnosus GG VTT E-96666); 21, control reaction with no template DNA.