Long-term persistence of ciprofloxacin-resistant Haemophilus influenzae in patients with cystic fibrosis

J Infect Dis. 1996 Dec;174(6):1345-7. doi: 10.1093/infdis/174.6.1345.


Ciprofloxacin has been a major advance in the treatment of chronic respiratory infections. Three patients with cystic fibrosis and colonized by 5 nontypeable Haemophilus influenzae strains exhibiting low- (MIC, 2 microg/mL) and high-level ciprofloxacin resistance (MICs, 16-32 microg/mL) are described. The patients had received several courses of ciprofloxacin. These MICs represent a decrease in ciprofloxacin susceptibility of 200-3200 times. Molecular epidemiologic methods demonstrated that 2 patients were chronically colonized by their own ciprofloxacin-resistant strains for > or = 15-17 months. Three strains showed simultaneous resistance to ampicillin and chloramphenicol by enzyme inactivation, and 2 had ampicillin resistance without beta-lactamase activity. These data suggest that the emergence and long-term persistence of ciprofloxacin-resistant H. influenzae in patients with cystic fibrosis can be a consequence of antibiotic treatment.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ampicillin Resistance
  • Anti-Infective Agents / therapeutic use*
  • Chloramphenicol Resistance
  • Ciprofloxacin / therapeutic use*
  • Cystic Fibrosis / microbiology*
  • Drug Resistance, Microbial
  • Electrophoresis, Gel, Pulsed-Field
  • Female
  • Haemophilus Infections / drug therapy*
  • Haemophilus influenzae / drug effects
  • Haemophilus influenzae / growth & development
  • Humans
  • Male
  • Microbial Sensitivity Tests
  • Molecular Epidemiology
  • Polymorphism, Restriction Fragment Length
  • beta-Lactamases / metabolism


  • Anti-Infective Agents
  • Ciprofloxacin
  • beta-Lactamases