A team from Germany investigated the intestinal mucosal flora of patients with inflammatory bowel disease.
Washed colonoscopic biopsies of 305 patients with bowel inflammation and 40 controls were assessed.
Microbial cultures were validated by quantitative polymerase chain reaction, with subsequent cloning and sequencing, fluorescence in-situ hybridization, and electron microscopy.
The authors found high concentrations of mucosal bacteria in patients with bowel inflammation, but not in controls.
The concentrations of mucosal bacteria increased progressively with the severity of disease, both in inflamed and non-inflamed colon.
| Mucosal bacteria concentrations progressively increased with the severity of IBD.
| Gastroenterology |
In patients with > 10,000 cfu/µl, a thick bacterial band was attached to the intact mucosa without signs of translocation.
Patients with inflammatory bowel disease and concentrations of mucosal bacteria > 50,000 cfu/µl had characteristic inclusions of multiple polymorphic bacteria within solitary enterocytes, located next to the lamina propria, without having contact with the fecal stream.
The researchers found that the identified bacteria were of fecal origin.
Alexander Swidsinski, of the Charité Humboldt University, Berlin, said on behalf of his colleagues, "Our findings suggest that the changes in the mucosal flora in IBD are not secondary to inflammation, but a result of a specific host response."
"We hypothesize that the healthy mucosa is capable of holding back fecal bacteria and that this function is profoundly disturbed in patients with IBD," he concluded.