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MOLECULAR STUDY OF THE IMPACT OF ORAL PEG-ELECTROLYTE SOLUTION ON THE COLONIC MICROBIOTA IN HEALTHY PATIENTS UNDERGOING SCREENING COLONOSCOPY
PJ Belletrutti, J Kaufman, T Lynch, T Griffiths, KP Rioux
Gastrointestinal Research Group, Department of Medicine, University of Calgary, Calgary, Alberta
In preparation for colonoscopy, patients are required to ingest an oral cathartic solution to allow for adequate mucosal visualization. The effect of colonic cleansing on intestinal microbiota is poorly characterized.
METHODS: Healthy patients undergoing screening colonoscopy were studied. On the day prior to colonoscopy, patients ingested 4L of GoLYTELY™ and were otherwise on a clear fluid diet, fasting after midnight. In total, four stool samples were collected and stored immediately at –20°C: 1 week prior to colonoscopy, the first formed stool after colonoscopy, and at 1 week and 1 month post-procedure. Stool bacterial DNA was extracted using a commercially available kit modified to include a bead-beading step. PCR was then performed using GC-clamped primers targeting a hypervariable region of the bacterial 16S rRNA gene. Amplicons were then separated using denaturing gradient gel electrophoresis (DGGE), an established means of bacterial community fingerprinting where each band represents a dominant group of bacteria.
RESULTS: Our preliminary analysis included 7 patients (age range 48-70 years, mean age 60 years). As expected, the baseline fecal microbiota varied somewhat among the subjects at baseline. When pre- and post-colonoscopy DGGE profiles were analyzed within each subject, 5 patients were found to have noticeable changes in the microbiota of the first formed stool after colonoscopy. There was no common pattern as to which dominant groups of bacteria were affected among these subjects. These changes were transient, as the baseline microbiota was restored in all subjects by 1 week after the procedure. In the remaining 2 patients, there were no noticeable changes in the stool microbiota.
CONCLUSIONS: Transient changes in the stool microbiota are observed in healthy patients using oral PEG-electrolyte solution in preparation for screening colonoscopy. The changes in baseline microbiota are fully reconstituted by one week after the procedure.