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Original article
Effects of bowel cleansing on the intestinal microbiota
  1. Jonna Jalanka1,
  2. Anne Salonen2,
  3. Jarkko Salojärvi1,
  4. Jarmo Ritari1,
  5. Outi Immonen1,
  6. Luca Marciani3,
  7. Penny Gowland4,
  8. Caroline Hoad4,
  9. Klara Garsed3,
  10. Ching Lam3,
  11. Airi Palva1,
  12. Robin C Spiller3,
  13. Willem M de Vos1,2,5
  1. 1Department of Veterinary Biosciences, Microbiology, University of Helsinki, Helsinki, Finland
  2. 2Immune Biology Research Program, Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland
  3. 3NIHR Biomedical Research Unit, Nottingham Digestive Diseases Centre, University Hospital, Nottingham, UK
  4. 4Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, UK
  5. 5Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
  1. Correspondence to Jonna Jalanka, Department of Veterinary Biosciences, University of Helsinki P.O. Box 66, Helsinki FI-00014, Finland; Jonna.Jalanka{at}


Objective An adequate bowel cleansing is essential for a successful colonoscopy. Although purgative consumption is safe for the patient, there is little consensus on how the intestinal microbiota is affected by the procedure, especially regarding the potential long-term consequences.

Design 23 healthy subjects were randomised into two study groups consuming a bowel preparation (Moviprep), either in two separate doses of 1 L or as a single 2-L dose. Participants donated faecal samples at the baseline, after bowel cleansing, 14 and 28 days after the treatment. The intestinal microbiota composition was determined with phylogenetic microarray as well as quantitative PCR analysis and correlated with the previously quantified faecal serine proteases.

Results The lavage introduced an instant and substantial change to the intestinal microbiota. The total microbial load was decreased by 31-fold and 22% of the participants lost the subject-specificity of their microbiota. While the bacterial levels and community composition were essentially restored within 14 days, the rate of recovery was dose dependent: consumption of the purgative in a single dose had a more severe effect on the microbiota composition than that of a double dose, and notably increased the levels of Proteobacteria, Fusobacteria and bacteria related to Dorea formicigenerans. The abundance of the latter also correlated with the amount of faecal serine proteases that were increased after purging.

Conclusions Our results suggest that the bowel cleansing using two separate dosages introduces fewer alterations to the intestinal microbiota than a single dose and hence may be preferred in clinical practice.


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