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Intestinal TM7 bacterial phylogenies in active inflammatory bowel disease

Tanja Kuehbacher^1,, Ateequr Rehman^2,, Patricia Lepage², Stephan Hellmig¹, Ulrich R. Fölsch¹, Stefan Schreiber^1,2 and Stephan J. Ott^1,2

¹ Clinic for General Internal Medicine, I. Medical Department, University Hospital Schleswig-Holstein (UKSH), Campus Kiel, Brunswiker Str. 10, D-24105 Kiel, Germany

² Institute for Clinical Molecular Biology (IKMB), Christian-Albrechts-Universität (CAU) Kiel, Schittenhelmstr. 12, D-24105 Kiel, Germany

Correspondence
Stephan J. Ott
s.ott{at}mucosa.de

Received October 25, 2007
Accepted August 24, 2008

TM7 is a recently described subgroup of Gram-positive uncultivable bacteria originally found in natural environmental habitats. An association of the TM7 bacterial division with the inflammatory pathogenesis of periodontitis has been previously shown. This study investigated TM7 phylogenies in patients with inflammatory bowel diseases (IBDs). The mucosal microbiota of patients with active Crohn's disease (CD; n=42) and ulcerative colitis (UC; n=31) was compared with that of controls (n=33). TM7 consortia were examined using molecular techniques based on 16S rRNA genes, including clone libraries, sequencing and in situ hybridization. TM7 molecular signatures could be cloned from mucosal samples of both IBD patients and controls, but the composition of the clone libraries differed significantly. Taxonomic analysis of the sequences revealed a higher diversity of TM7 phylotypes in CD (23 different phylotypes) than in UC (10) and non-IBD controls (12). All clone libraries showed a high number of novel sequences (21 for controls, 34 for CD and 29 for UC). A highly atypical base substitution for bacterial 16S rRNA genes associated with antibiotic resistance was detected in almost all sequences from CD (97.3 %) and UC (100 %) patients compared to only 65.1 % in the controls. TM7 bacteria might play an important role in IBD similar to that previously described in oral inflammation. The alterations of TM7 bacteria and the genetically determined antibiotic resistance of TM7 species in IBD could be a relevant part of a more general alteration of bacterial microbiota in IBD as recently found, e.g. as a promoter of inflammation at early stages of disease.

Abbreviations: CD, Crohn's disease; IBD, inflammatory bowel disease; OTUs, operational taxonomic units; UC, ulcerative colitis.

These authors contributed equally to this work.

The GenBank/EMBL/DDBJ accession numbers for the TM7 clone sequences are EU056368–EU056522 and EU056524–EU056533.