The mucosa-associated bacteria from the sigmoid colon of nine healthy 60 years old individuals, identified by bacterial 16S rDNA.

The bacterial flora of the gastro intestinal (GI) tract may be involved in chronic inflammation and colon cancer and affected by antibiotics, cytotoxic drugs and radiotherapy, trauma and intensive care therapy. It is important to map the mucosa-associated flora in healthy individuals to clarify the pathogenic risk under stressed conditions. The aim was to achieve an overview of the mucosa-associated bacterial flora in the sigmoid colon by direct 16S rDNA identification by sampling nine 60-years old volunteers, without clinical symptoms or medication. The bacterial flora was estimated by sequence analysis of cloned 16S rDNA as enriched by PCR from biopsies. 26% of the clones had ≥99% similarity to known species (36% had ≥98% similarity). The largest number of identified clones was related to Escherichia coli, Bacteroides vulgatus and Ruminicoccus torques. Most frequently distributed between the volunteers were Bacteroides uniformis and Bacteroides vulgatus (7 individuals). Bacteroides caccae, Bacteroides distasonis, Bacteroides putredinis, Bacteroides thetaiotaomicron and Ruminicoccus torques were found in 5 persons. Opportunistic pathogens found in more than one individual were Bacteroides fragilis, Escherichia coli and Bilophila wadsworthia. Acinetobacter baumannii, Brachyspira aalborgi, Cardiobacterium hominis, Clostridium perfringens, Klebsiella pneumoniae and Veillonella parvula were found in single individuals. A majority of the individuals had a heterogeneous flora but in one person, 91% of the clones were related to E. coli. The GI-flora differs between healthy individuals in respect to both composition and diversity, and it can include several opportunistic pathogens. (Less)