Chloramphenicol- and tetracycline-resistant uropathogenic Escherichia coli (UPEC) exhibit reduced virulence potential

Int J Antimicrob Agents. 2007 Nov;30(5):436-42. doi: 10.1016/j.ijantimicag.2007.06.025. Epub 2007 Aug 24.


It is well documented that uropathogenic Escherichia coli (UPEC) isolates resistant to nalidixic acid have reduced virulence potential. Our goal was to assess whether UPEC isolates resistant to chloramphenicol, tetracycline and streptomycin also exhibit reduced virulence potential. Among 110 human UPEC isolates, the prevalences of the virulence factors fimH, papC, papGII, papGIII, sfa/focDE, afa, hlyA, cnf1, usp, ibeA, fyuA, iroN, iucD, ireA, and K1 and K5 capsules as well as of pathotypes, phylogenetic groups, O antigens and a pathogenicity island (PAI) marker were compared between chloramphenicol-, tetracycline-, streptomycin- and, as a control, nalidixic acid-resistant and -susceptible strains. Our findings show that among human UPEC isolates, not only nalidixic acid-resistant but also chloramphenicol- and tetracycline-resistant isolates have reduced virulence potential compared with susceptible strains. To our knowledge, this is the first report of a statistically significant reduction in virulence traits among chloramphenicol- and tetracycline-resistant isolates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Chloramphenicol Resistance*
  • Escherichia coli / drug effects*
  • Escherichia coli / growth & development*
  • Escherichia coli / pathogenicity
  • Escherichia coli Infections / microbiology*
  • Genomic Islands / genetics
  • Humans
  • Nalidixic Acid / pharmacology
  • O Antigens / analysis
  • Streptomycin / pharmacology
  • Tetracycline Resistance*
  • Urinary Tract Infections / microbiology*
  • Virulence
  • Virulence Factors / genetics


  • Anti-Bacterial Agents
  • O Antigens
  • Virulence Factors
  • Nalidixic Acid
  • Streptomycin