Fluoroquinolone resistance associated with specific gyrase mutations in clinical isolates of multidrug-resistant Mycobacterium tuberculosis

J Infect Dis. 1996 Nov;174(5):1127-30. doi: 10.1093/infdis/174.5.1127.


Fluoroquinolones are potent antibacterial agents being used clinically against multidrug-resistant tuberculosis. Treatment failure is thought to arise from acquisition of fluoroquinolone resistance by Mycobacterium tuberculosis. A collection of 13 resistant clinical isolates of M. tuberculosis was examined for ciprofloxacin sensitivity relative to controls exhibiting the same IS6110 DNA type. Specific alleles were associated with distinct levels of drug susceptibility for 11 isolates that contained nucleotide changes expected to alter the amino acid sequence of the A subunit of DNA gyrase. Five different gyrA (ciprofloxacin resistance) alleles were present among 7 isolates having the W DNA subtype. These isolates, which are representative of an outbreak strain, constitute a panel of organisms that can be used to evaluate contributions of gyrase and DNA topoisomerase IV to resistance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anti-Infective Agents / pharmacology*
  • Ciprofloxacin / pharmacology*
  • DNA Topoisomerases, Type II / genetics*
  • DNA Topoisomerases, Type II / physiology
  • Drug Resistance, Multiple
  • Humans
  • Mutation
  • Mycobacterium tuberculosis / drug effects*
  • Mycobacterium tuberculosis / enzymology


  • Anti-Infective Agents
  • Ciprofloxacin
  • DNA Topoisomerases, Type II