Comparative study of bacterial groups within the human cecal and fecal microbiota

The composition of the human cecal microbiota is poorly known because of sa mpling difficulties. Samples of cecal fluid from eight subjects were collec ted via an intestinal tube. Feces were also collected. Total anaerobes, fac ultative anaerobes, bifidobacteria, and Bacteroides were enumerated by cult ure methods, and the predominant phylogenetic groups were quantified by mol ecular hybridization using a set of six rRNA-targeted probes. The numbers o f strict anaerobes, bifidobacteria, Bacteroides, and members of the Clostri dium coccoides group and Clostridium leptum subgroup were lower in the cecu m. Facultative anaerobes represented 25% of total bacteria in the cecum ver sus 1% in the feces.