Decreased susceptibility to azithromycin and erythromycin mediated by a novel mtr(R) promoter mutation in Neisseria gonorrhoeae

J Antimicrob Chemother. 2001 May;47(5):651-4. doi: 10.1093/jac/47.5.651.


During a screen of Neisseria gonorrhoeae clinical isolates obtained in Uruguay for susceptibility to azithromycin, we noticed that approximately 10% of the strains examined displayed decreased susceptibility to azithromycin and erythromycin due to the mtr(CDE)-encoded efflux pump system, but remained susceptible to Triton X-100. We now report that the mtr(R) promoter region of one of these isolates contains a dinucleotide insertion (TT) that mediates this resistance phenotype.

Publication types

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

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Azithromycin / pharmacology
  • Bacterial Proteins*
  • DNA, Bacterial / analysis
  • Drug Resistance, Microbial / genetics
  • Drug Resistance, Multiple / genetics*
  • Erythromycin / pharmacology
  • Ferredoxin-NADP Reductase*
  • Gene Expression
  • Humans
  • Male
  • Mutation
  • Neisseria gonorrhoeae / drug effects
  • Neisseria gonorrhoeae / genetics*
  • Promoter Regions, Genetic / genetics*
  • Repressor Proteins / genetics*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • DNA, Bacterial
  • Repressor Proteins
  • mtrR protein, Neisseria gonorrhoeae
  • Erythromycin
  • Azithromycin
  • methionine synthase reductase
  • Ferredoxin-NADP Reductase