Characterization of inducible stx2-positive Escherichia coli O157:H7/H7- strains isolated from cattle in France.
Résumé
AIMS: To quantify the variability of the Shiga toxin 2 (Stx2) production by a panel of stx2-positive Escherichia coli O157:H7/H7- isolates from healthy cattle before and after induction with enrofloxacin. METHODS AND RESULTS: ProSpecT ELISA was used to quantify the Stx2 production by stx2-positive E. coli O157:H7/H7- isolates in native conditions (basal level) or after induction with enrofloxacin. Whereas only 15.2% of the E. coli O157:H7/H7- strains studied displayed significant amounts of detectable Stx2 without induction, most of them were shown to be inducible, and at various levels, in presence of subinhibitory concentrations of enrofloxacin. CONCLUSIONS: We demonstrated the capability of a highly elevated proportion of stx2-positive, but constitutively Stx2-negative, E. coli O157:H7/H7- isolates from healthy cattle to produce significant levels of Shiga toxin Stx2 in presence of subtherapeutic concentrations of enrofloxacin, an antibiotic of the fluoroquinolones family only licensed for veterinary use. SIGNIFICANCE AND IMPACT OF THE STUDY: This study documents the risk that bovine-associated Shiga toxin producing E. coli isolates may become more frequently pathogenic to humans as a side-effect of the increasing use of veterinary fluoroquinolones in the oral treatment of food animals like cattle or poultry.
Mots clés
1UVIROLOGIE HAFSSA AUTRE Animals Antibodies
Viral/blood *Biolistics Epidermis/virology Female Genes
env/*genetics/immunology Genes
gag/*genetics/immunology Immunization Male Pneumonia
Progressive Interstitial
of Sheep/*prevention & control/virology Proviruses/isolation & purification Sheep T-Lymphocytes/immunology *Vaccines
DNA/administration & dosage/genetics/immunology Vaccinia virus/*genetics/immunology Viral Vaccines/administration & dosage/genetics/immunology Virion/genetics/immunology Visna-maedi virusenrofloxacin
Escherichia coli
fluoroquinolones
O157:H7
Shiga toxin
STEC