Fluoroquinolone resistance linked to GyrA, GyrB, and ParC mutations in Salmonella enterica typhimurium isolates in humans

Emerg Infect Dis. 2003 Nov;9(11):1455-7. doi: 10.3201/eid0911.030317.


We report two cases of infection with clonally unrelated, high-level ciprofloxacin-resistant, b-lactamase-producing strains of Salmonella enterica Typhimurium. Resistance was caused by four topoisomerase mutations, in GyrA, GyrB, and ParC and increased drug efflux. Ciprofloxacin treatment failed in one case. In the second case, reduced susceptibility to third-generation cephalosporins occurred after initial treatment with these drugs and may explain the treatment failure with ceftriaxone.

Publication types

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

MeSH terms

  • Aged
  • Anti-Infective Agents / therapeutic use*
  • Ciprofloxacin / therapeutic use*
  • DNA Gyrase / drug effects
  • DNA Gyrase / genetics*
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Fluoroquinolones / therapeutic use*
  • Humans
  • Infant
  • Male
  • Microbial Sensitivity Tests
  • Salmonella Infections / drug therapy*
  • Salmonella typhimurium / drug effects
  • Salmonella typhimurium / genetics*


  • Anti-Infective Agents
  • Fluoroquinolones
  • Ciprofloxacin
  • DNA Gyrase