Objectives: Bacterial imbalance may be involved in the pathogenesis of diversion colitis, via diminished production of short chain fatty acids. The aim of the study was to evaluate the effectiveness of short chain fatty acids on microbial flora of patients with diversion colitis and to compare this flora to the microbial flora of controls.
Methods: We prospectively evaluated the effectiveness of short chain fatty acids irrigation on bacterial flora of the excluded colon in 13 patients (8 males, 5 females; mean age: 43.7 years). The causes of diversion were inflammatory bowel disease (n = 4) colonic cancer (n = 2) sigmoid diverticulitis with perforation (n = 3) ischio-rectal abscess (n = 2) and miscellaneous (n = 2). Patients were given, twice a day for 14 days in a double blind manner, a 60 mL enema containing either short chain fatty acids (acetate: 60 mmol/L; propionate: 30 mmol/L; and n-butyrate: 40 mmol/L) (group 1; n = 7) or isotonic NaCl (group 2; n = 6). Bacteriological studies were carried on before starting the trial (D1) and 14 days later (D14).
Results: Before and after treatment, there was no difference between group 1 and group 2 concerning bacterial counts and species. Bacterial flora of patients with diversion colitis was characterized by: a) an increase of the count of aerobic bacteria; b) an increase of aerobic and aeroanaerobic species; c) the presence of black pigmented Gram negative anaerobic rods such as Prevotella intermedia and Porphyromonas asaccharolytica which were not found in rectal flora of the control group (16 volunteers, mean age: 27 years).
Conclusions: These data suggest that: a) enema with short chain fatty acids does not induce significant changes in the composition of the microbial flora in patients with diversion colitis; b) bacterial dysbiosis may be involved in pathogenesis of diversion colitis without involving the action of short chain fatty acids.