Influence of ofloxacin on the faecal flora.

In a continuing, Norwegian-Swedish collaborative study, the effects of several antimicrobials upon intestinal biochemical microflora-associated characteristics are being investigated. In the present study, 7 healthy volunteers were given ofloxacin 200mg bid for 6 days. Faecal sampling was performed twice before, on days 3 and 6 during treatment, and weekly to monthly afterwards. Blood sampling was performed on day 6 during treatment. The concentrations of ofloxacin were measured in faeces and serum on day 6. Additionally, the following microflora-associated characteristics were studied in all the faecal samples: presence of short chain fatty acids, absence of beta-aspartylglycine, production of coprostanol, formation of urobilinogen, inactivation of tryptic activity and breakdown of mucin. The mean concentrations of ofloxacin in faeces and serum were 44.0 mg/kg and 2.1 mg/L, respectively. In contrast to most of the other antimicrobials so far tested, ofloxacin exerted almost no influence upon the microflora-associated characteristics investigated.