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Virulence genotype and nematode-killing properties of extra-intestinal Escherichia coli producing CTX-M

J-P Lavigne1, A-B Blanc-Potard, G Bourg

  • 1Laboratoire Universitaire d'Antibiologie, UFR de Médecine, Nîmes, France.

Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
|November 24, 2006
PubMed

Insights

Hospital-acquired Escherichia coli producing CTX-M beta-lactamases show reduced virulence. These extended-spectrum beta-lactamase (ESBL)-producing strains, common in urinary tract infections, possess fewer virulence factors and lower pathogenicity in vivo.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are a growing concern in healthcare settings.
  • CTX-M beta-lactamases are frequently identified in ESBL-producing E. coli, particularly in urinary tract infections.
  • Understanding the virulence potential of these antibiotic-resistant strains is crucial for infection control.

Purpose of the Study:

  • To evaluate the virulence potential of CTX-M beta-lactamase-producing Escherichia coli.
  • To compare the prevalence of virulence factors (VFs) in ESBL-producing E. coli with susceptible strains.
  • To assess the in vivo pathogenicity of CTX-M-producing E. coli using a novel nematode infection model.

Main Methods:

  • Isolates of extended-spectrum beta-lactamase (ESBL)-producing and susceptible Escherichia coli were collected from urinary tract infections.
  • Polymerase chain reaction (PCR) was used to investigate the prevalence of 14 major virulence factors (VFs).
  • Virulence was assessed in vivo using infection assays with the nematode Caenorhabditis elegans.

Main Results:

  • ESBL-producing E. coli isolates showed a lower prevalence of most virulence factors compared to susceptible strains.
  • CTX-M-producing isolates exhibited significantly fewer virulence factors than TEM-producing isolates.
  • In vivo assays demonstrated that CTX-M-producing E. coli had relatively low virulence, with nematode killing ability correlating with VF presence.

Conclusions:

  • Hospital-acquired CTX-M-producing E. coli, despite antibiotic resistance, possess a lower intrinsic virulence potential.
  • These strains appear adapted for survival in antibiotic-rich hospital environments rather than for high pathogenicity.
  • Further research into the evolutionary trade-offs between antibiotic resistance and virulence in E. coli is warranted.

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