Impact of prolonged treatment with high-dose ciprofloxacin on human gut flora: a case report

INTRODUCTION: Ciprofloxacin is a commonly marketed fluoroquinolone. It is not effective against obligate anaerobes, hence it is considered unlikely to have an impact on colonic microflora. We report the case of a patient who received prolonged treatment with high-dose ciprofloxacin for extensive pelvic osteomyelitis. We also report on the medication's effects on his bowel flora. To the best of our knowledge, this is the first report discussing the effects of prolonged administration of a quinolone on microbial flora. CASE PRESENTATION: A 62-year-old Caucasian man with diabetes presented with low back pain of four months' duration. A magnetic resonance imaging of his pelvis revealed sacroiliitis and extensive pelvic osteomyelitis. Pseudomonas aeruginosa, which is susceptible to ciprofloxacin, was noted as the offending pathogen. After seven weeks of intravenous treatment, he was prescribed with high-dose oral ciprofloxacin that he continued to take for the next 20 months. Quantitative stool cultures of our patient were obtained a month later as well as at the end of his treatment to record his corresponding sensitivities to the medication. The Gram-negative population of his bowel flora was restored fully upon the discontinuation of this medication. The Gram-negative population was shown to be fully sensitive to ciprofloxacin. His yeast levels were also found to be slightly increased, and no growth of resistant enterococci was noted. CONCLUSION: The findings of this case report suggest that long term and high dose ciprofloxacin administration might be safe in preventing the risk of colonization with resistant Gram negative pathogens, overgrowth of anaerobes and the development of resistant enterococci.