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Gut Online First, published on February 13, 2015 as 10.1136/gutjnl-2014-308937 Commentary
Bowel preparation for colonoscopy: relevant for the gut’s microbiota? Volker Mai,1 O Colin Stine2 Potential contributions of the hostassociated gut microbiota to human physiology continue to receive extensive research interest. While various lines of evidence support a role of the microbiota in maintaining human health, perturbations in normal microbiota composition have been correlated with various dietary changes and disease states,1 particularly diarrhoea.2 We have long known that close interactions between microbiota and the host’s immune system occur in the distal small intestine and that microbes are highly metabolically active in the proximal large intestine. Recent global efforts have accumulated a wealth of data on the diversity of human gut-associated microbiota. These studies confirmed that even in healthy individuals a large degree of intraindividual as well as interindividual variation in microbiota composition and although to a lesser degree, microbial activities occur. However, what represents ‘normal’ gut microbiota is still not fully understood, which is largely due to the observed variation within and among individuals. While recent work based on phylogenetic analysis of both the small subunit (16S) of ribosomal RNA as well as metagenomic datasets suggests the existence of distinct enterotypes,3 other studies suggest more of a continuous spectrum of microbiota composition.4 5 Although large efforts over the last decade have advanced our understanding of microbiota composition and its unique metabolic functions, our insight into microbiota dynamics, especially when associated with life events prone to distort its composition, such as changes in transit time, nutrient availability or exposure to antibiotics, remains poorly defined. In this issue Jalanka et al6 report on a study that determined the effects of two colon cleansing regimens, commonly used as a preparation for colonoscopy-based colorectal cancer screening, on faecal microbiota composition. While limited
1
Department of Epidemiology, Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA; 2 Department of Epidemiology and Public Health, University of Maryland, Baltimore, Maryland, USA Correspondence to Dr O Colin Stine, Department of Epidemiology and Public Health, University of Maryland, 585 Howard Hall, 660 W. Redwood Street, Baltimore, MD 21201 USA; [email protected]
data on the reestablishment of gut microbiota after a colonoscopy procedure,7–9 this is the first study that compared administration of a bowel preparation solution (Moviprep), when administered in one or two doses. The authors report distinct differences of the two regimens; while the split dose decreased microbiota concentration in faeces more effectively than the single dose, indicative of a more efficient cleaning of the gut, it was associated with less distortions of microbiota composition during the recovery period. A total of 23 individuals participated in this study, providing more statistical power for comparing microbiota compositions than the smaller previous studies. Consistent with the widely accepted hypothesis that individuals harbour distinct microbiota, samples generally clustered by individual rather than by time point. The exceptions were the samples collected immediately after lavage from five subjects. Even in those five individuals the microbiota returned to cluster with the individuals by day 14, suggesting that long-term microbiota changes were not associated with either cleansing regimen in the healthy young participants (mean age
Gut Online First, published on February 13, 2015 as 10.1136/gutjnl-2014-308937 Commentary
Bowel preparation for colonoscopy: relevant for the gut’s microbiota? Volker Mai,1 O Colin Stine2 Potential contributions of the hostassociated gut microbiota to human physiology continue to receive extensive research interest. While various lines of evidence support a role of the microbiota in maintaining human health, perturbations in normal microbiota composition have been correlated with various dietary changes and disease states,1 particularly diarrhoea.2 We have long known that close interactions between microbiota and the host’s immune system occur in the distal small intestine and that microbes are highly metabolically active in the proximal large intestine. Recent global efforts have accumulated a wealth of data on the diversity of human gut-associated microbiota. These studies confirmed that even in healthy individuals a large degree of intraindividual as well as interindividual variation in microbiota composition and although to a lesser degree, microbial activities occur. However, what represents ‘normal’ gut microbiota is still not fully understood, which is largely due to the observed variation within and among individuals. While recent work based on phylogenetic analysis of both the small subunit (16S) of ribosomal RNA as well as metagenomic datasets suggests the existence of distinct enterotypes,3 other studies suggest more of a continuous spectrum of microbiota composition.4 5 Although large efforts over the last decade have advanced our understanding of microbiota composition and its unique metabolic functions, our insight into microbiota dynamics, especially when associated with life events prone to distort its composition, such as changes in transit time, nutrient availability or exposure to antibiotics, remains poorly defined. In this issue Jalanka et al6 report on a study that determined the effects of two colon cleansing regimens, commonly used as a preparation for colonoscopy-based colorectal cancer screening, on faecal microbiota composition. While limited
1
Department of Epidemiology, Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA; 2 Department of Epidemiology and Public Health, University of Maryland, Baltimore, Maryland, USA Correspondence to Dr O Colin Stine, Department of Epidemiology and Public Health, University of Maryland, 585 Howard Hall, 660 W. Redwood Street, Baltimore, MD 21201 USA; [email protected]
data on the reestablishment of gut microbiota after a colonoscopy procedure,7–9 this is the first study that compared administration of a bowel preparation solution (Moviprep), when administered in one or two doses. The authors report distinct differences of the two regimens; while the split dose decreased microbiota concentration in faeces more effectively than the single dose, indicative of a more efficient cleaning of the gut, it was associated with less distortions of microbiota composition during the recovery period. A total of 23 individuals participated in this study, providing more statistical power for comparing microbiota compositions than the smaller previous studies. Consistent with the widely accepted hypothesis that individuals harbour distinct microbiota, samples generally clustered by individual rather than by time point. The exceptions were the samples collected immediately after lavage from five subjects. Even in those five individuals the microbiota returned to cluster with the individuals by day 14, suggesting that long-term microbiota changes were not associated with either cleansing regimen in the healthy young participants (mean age
