Digestive tolerance of inulin-type fructans: a double-blind, placebo-controlled, cross-over, dose-ranging, randomized study in healthy volunteers.

BACKGROUND: Similar to other indigestible carbohydrates or dietary fibres, a consumption of too large quantities of inulin-type fructans may cause some digestive problems. AIM: To compare the digestive tolerance of inulin-type fructans, administered during 2 weeks, at different doses. METHODS: Eighty-four healthy volunteers (aged 18-45 years, mean body mass index 25.1 kg/m2 and mean total fibre consumption 12 g) were included in a double-blind, placebo-controlled, randomized, cross-over study comparing Fibrulose F97 (5 and 20 g/day), Fibruline Instant (5, 10 and 20 g/day) and Fibruline XL (10 g/day) (degrees of polymerization respectively equal to 2-20, 2-60 with an average of 10, and 2-60 with an average >20) to placebo. The study was decomposed into five 2-week periods: placebo run-in, treatment 1, placebo washout, treatment 2, placebo run-out. The following symptoms were assessed using visual analogue scales: flatulence, rumbling, bloating, abdominal pain, abdominal cramps, nausea, stool frequency and stool consistency. The primary variable was the mean difference between treatment and placebo in terms of tolerance (sum of the eight visual analogue scales). RESULTS: The three products tended to increase digestive symptoms whatever the dose but the change was mild (maximum, +19 mm on the 800-mm scale) and significant (P<0.001) for Fibruline Instant at 20 g/day only. At 20 g/day, a statistically significant difference between Fibruline Instant and Fibrulose F97 was demonstrated (P=0.011). There was a dose-effect relationship both for Fibrulose F97 (P>0.05) and Fibruline Instant (P=0.042). All the other tendencies were non-significant. CONCLUSIONS: The three different inulin-type fructans were very well tolerated.

Toxin A detection on Clostridium difficile colonies from 24-h cultures.

OBJECTIVE: Performance of a combined approach for the detection of toxigenic strains in patients suspected of having Clostridium difficile-associated disease was evaluated. METHODS: In this approach, stools were cultured for 24 h on a selective medium supplemented with sodium taurocholate (TCCFA), in anaerobic conditions created with the Martreg Anoxomat system, and toxin A detection was performed directly on C. difficile colonies, by enzyme immunoassay (EIA). This method was compared with three others: cytotoxigenic culture consisting of a 48-h culture on selective medium followed by detection of in vitro cytotoxin production on cell monolayers, fecal cytotoxin detection and fecal toxin A detection by EIA. RESULTS: From 548 stools, 108 yielded a positive culture by at least one of the methods, and 81 isolates were cytotoxin producers. Cultures for 24 h on TCCFA were positive in 106 cases and EIA performed on colonies gave 73 positive results, giving a sensitivity of 90.1% and a specificity of 100%. By comparison, the sensitivity and specificity of cytotoxigenic culture, stool cytotoxin and stool toxin A were respectively 96.2% and 100%, 61.7% and 100%, and 66.7% and 95.9%. CONCLUSIONS: Performing EIA on colonies recovered after 24 h culture allows us to improve the detection of toxigenic strains in patients suspected of having C. difficile-associated disease.