Ciprofloxacin or metronidazole for the treatment of perianal fistulas in patients with Crohn's disease: a randomized, double-blind, placebo-controlled pilot study

Inflamm Bowel Dis. 2009 Jan;15(1):17-24. doi: 10.1002/ibd.20608.


Background: Although metronidazole and ciprofloxacin are used to treat perianal Crohn's disease (CD), no placebo-controlled trials have been performed.

Methods: We performed a placebo-controlled pilot trial to evaluate the efficacy and safety of metronidazole and ciprofloxacin in patients with perianal CD. Twenty-five patients with CD and actively draining perianal fistulas were randomized to receive ciprofloxacin 500 mg, metronidazole 500 mg, or placebo twice daily for 10 weeks. Remission and response of perianal fistulas were defined as closure of all fistulas and closure of at least 50% of fistulas that were draining at baseline, respectively. The primary endpoint was remission at 10 weeks.

Results: Ten patients were randomized to ciprofloxacin, 7 to metronidazole, and 8 to placebo. Remission at week 10 occurred in 3 patients (30%) treated with ciprofloxacin, no patients (0%) treated with metronidazole, and 1 patient (12.5%) treated with placebo (P = 0.41). Response at week 10 occurred in 4 patients (40%) treated with ciprofloxacin, 1 patient (14.3%) treated with metronidazole, and 1 patient (12.5%) treated with placebo (P = 0.43). Termination of the trial prior to week 10 occurred in 1 patient (10%) treated with ciprofloxacin, 5 patients (71.4%) treated with metronidazole, and 1 patient (12.5%) treated with placebo (P < 0.02). No serious adverse events occurred.

Conclusion: Remission and response occurred more frequently in patients treated with ciprofloxacin but the differences were not significant in this pilot study. Ciprofloxacin was well tolerated.

Publication types

  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-Infective Agents / therapeutic use*
  • Ciprofloxacin / therapeutic use*
  • Crohn Disease / drug therapy*
  • Double-Blind Method
  • Female
  • Humans
  • Male
  • Metronidazole / therapeutic use*
  • Middle Aged
  • Placebos
  • Rectal Fistula / drug therapy*
  • Treatment Outcome


  • Anti-Infective Agents
  • Placebos
  • Metronidazole
  • Ciprofloxacin