Impact of oral ciprofloxacin on the faecal flora of healthy volunteers.

The intestinal flora was studied in 12 volunteers after the administration of 400 mg ciprofloxacin b.i.d. over seven days. Stool samples were taken prior to and several times after the initiation of therapy, and qualitative and quantitative analyses of microorganisms were performed. Escherichia coli was eliminated in all volunteers after two days of treatment. A selection of resistant enterobacteria could not be observed. A higher incidence of Streptococcus faecium was seen, mainly after the end of drug application. The number of cfu of Bacteroides and Bifidus species remained unchanged during the trial. There was no selection of Clostridium difficile. Based on this pattern of activity on the stool flora we suggest that ciprofloxacin could represent an appropriate drug for the therapy of bacterial intestinal infections as well as for selective decontamination in immunosuppressed patients.