Quinolone-resistance mutations in the topoisomerase IV parC gene of Acinetobacter baumannii

J Antimicrob Chemother. 1997 Jun;39(6):757-62. doi: 10.1093/jac/39.6.757.


Mutations in the parC gene, which encodes a subunit of topoisomerase IV, were determined in 21 epidemiologically unrelated clinical isolates of Acinetobacter baumannii. Our studies highlight the conserved sequences in the quinolone-resistance-determining region of the parC gene from A. baumannii and other bacteria. Nine of ten isolates with MICs of ciprofloxacin of > or = 32 mg/L showed a change of Ser80 to Leu and one showed a change of Glu84 to Lys. These results suggest that ParC from A. baumannii is a secondary target for quinolones and that mutations at residues Ser80 and Glu84, when combined with mutations at Ser83 of GyrA, may render A. baumannii highly resistant to quinolones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter / drug effects
  • Acinetobacter / genetics*
  • Amino Acid Sequence
  • Anti-Infective Agents / pharmacology
  • Base Sequence
  • Ciprofloxacin / pharmacology
  • DNA Topoisomerase IV
  • DNA Topoisomerases, Type I / genetics*
  • DNA Topoisomerases, Type II / genetics*
  • Drug Resistance, Microbial / genetics
  • Genes, Bacterial / genetics*
  • Molecular Sequence Data
  • Point Mutation*
  • Sequence Homology, Amino Acid


  • Anti-Infective Agents
  • Ciprofloxacin
  • DNA Topoisomerase IV
  • DNA Topoisomerases, Type I
  • DNA Topoisomerases, Type II

Associated data

  • GENBANK/X95819