Impact of rufloxacin and ciprofloxacin on the intestinal microflora in a germ-free mice model.

The impact of rufloxacin and ciprofloxacin on faecal microflora was investigated in an experimental germ-free mice model into which human gastrointestinal flora was introduced and stabilized. Animals received oral doses of 10, 40 or 80 mg rufloxacin/kg, 30 or 60 mg ciprofloxacin/kg once daily for 10 days, or no treatment. Microflora was studied before, during and 1 week after treatment. No significant effect ( < 2 log reduction, p > 0.05) on aerobic microflora was observed after rufloxacin as compared to controls, except for a marked decrease in enterobacteria and a slight decrease in enterococci, staphylococci and anaerobes at the highest dose. Both doses of ciprofloxacin significantly reduced enterobacteria and clostridia, while the lower dose slightly reduced peptococci, bifidobacteria and eubacteria. The depression of the intestinal ecosystem was reversible, except for enterobacteria at the higher ciprofloxacin dose. No bacterial resistance was detected after either treatment.