The short-term effects of different doses of dexamethasone on the numbers of some bacteria in the ileum.

Glucocorticoids are known to affect intestinal biota both directly or indirectly. The aim of the study reported here was to determine the short-term effects of different doses of dexamethasone on the numbers of various ileal bacteria populations. Rats were randomly put into groups, and each group was administered a single-dose injection of dexamethasone at either 0.1, 0.5, 1, 2.5, 5, or 10 mg/kg body weight. At 48-h post-injection, the numbers of total aerobe, anaerobe, lactobacilli and coliform bacteria in the ileum were determined. The numbers of total aerobes and lactobacilli were higher in the groups receiving 5 and 10 mg/kg dexamethasone than in the control and other dose groups (P < 0.01 and P < 0.001, respectively). The number of ileal anaerobic bacteria was higher in group receiving 5 mg/kg than in the other groups (P < 0.01). There were more coliform bacteria in the group receiving 0.1 mg/kg than in the groups receiving 0.5, 1 and 10 mg/kg (P < 0.05). In light of these results, the effects of dose-dependent increases in the number of different bacterial groups affecting gut functions have still to be determined in future studies.