Background: A major limitation in studying the proximal human colonic flora is the lack of suitable sampling methods. The aim of this study was (1) to describe a prototype technique, pyxigraphy, which uses swallowed capsules containing a mechanism allowing the remote control of sampling the gastrointestinal tract contents, and (2) to use this sampling method to examine the distribution of methanogens in the colon of methane (CH4) excretors and non-CH4 excretors.
Methods: In six CH4 excretors and four non-CH4 excretors, samples of the right colonic contents were obtained by means of the pyxigraphic sampling method. Methanogens and total anaerobes were enumerated in both the right colonic and fecal contents.
Results: In CH4 excretors, the concentration of methanogens was higher in the feces than in the right colonic contents, representing 12% and 0.003%, respectively, of the total anacrobes (P < 0.02). In non-CH4 excretors, no difference was observed, methanogens representing < 0.003% of the total anaerobes in both the right colonic and fecal contents.
Conclusions: Pyxigraphy is a noninvasive, simple, and safe sampling method that allows to study the microbial populations of the proximal colon. The results obtained showed that methanogens preferentially colonize the distal part of the colon in CH4 excretors.