The human gut microbiota is a complex bacterial community that is relatively stable over time. Disruption of the microbiota can increase the risk for several health complications, including loss of colonization resistance against bacterial pathogens and predisposition to autoimmune and allergic diseases. Altered gut microbiota has also been linked to serious gastrointestinal disorders, including irritable bowel syndrome.
This study used barcoded 454-pyrosequencing of the 16S rRNA gene to determine the microbiota diversity of human patients with Norovirus infection. The results demonstrate that some Norovirus-infected patients exhibit an altered intestinal microbiota, which may put them at elevated risk for health problems.
Disruption of the Human Gut Microbiota following Norovirus Infection. (2012) PLoS ONE 7(10): e48224. doi:10.1371/journal.pone.0048224
The gut microbiota, the collection of all bacterial members in the intestinal tract, plays a key role in health. Disruption of the indigenous microbiota by a variety of stressors, including antibiotic therapy and intestinal infections, is associated with multiple health problems. We sought to determine if infection with Norovirus disrupts the gut microbiota. Barcoded pyrosequencing of the 16S rRNA-encoding gene was used to characterize the stool microbiota in Norovirus-infected human patients (n = 38). While the microbiota in most infected patients (n = 31) resembled that seen in uninfected healthy controls, a minority of patients (n = 7) possessed a significantly altered microbiota characterized by reduced relative numbers of Bacteriodetes and a corresponding increase in Proteobacteria. In these patients, the increase in Proteobacteria was due to a single operational taxonomic unit (OTU) of Escherichia coli. We cultured E. coli from Norovirus-infected patients and characterized them using PCR-ribotyping and virulence factor analysis. Multiple ribotypes were encountered, but none possessed typical virulence factors commonly carried by enteropathogenic E. coli strains. Microbiota disruption and elevated Proteobacteria were not significantly correlated to patient age, gender, sampling time following illness onset, or overall gut inflammation. These results demonstrate that some patients have a disrupted microbiota following Norovirus infection, and therefore may be at elevated risk for long-term health complications.