Detection of Escherichia coli O157:H7 in heifers' faecal samples using an automated immunoconcentration system.
Pre-treatment of a 5-h enrichment culture with an automated immunoconcentration (ICE) system greatly improved the isolation of Escherichia coli O157:H7 from spiked heifer faecal samples. Enrichment samples plated directly onto sorbitol MacConkey agar (SMAC) and SMAC agar supplemented with cefixime and potassium tellurite (CT-SMAC) showed recovery rates of 8% and 56%, respectively. However, after ICE treatment, E. coli O157:H7 was recovered from 92% of the samples on SMAC and 100% on CT-SMAC. Immunoconcentration analysis of heifers' faecal samples collected from a slaughter-house in France, during March to June 1998, showed that 1% (three of 300) was positive for E. coli O157:H7. Phenotypic and genotypic analysis showed that all three isolates carried both the O157 and H7 antigens, did not ferment sorbitol or had beta-glucuronidase activity and carried trait virulence factors for E. coli O157:H7 (uidA allele, eaeA and pO157 plasmid). However, only one strain was toxigenic and this strain produced a single toxin, namely verotoxin 2.
Vernozy-Rozand
C
C
Unité de Microbiologie Alimentaire et Microbiologie Prévisionnelle, Ecole Nationale Vétérinaire de Lyon, Marcy l'Etoile, France. c.vernozy@vet-lyon.fr
Feng
P
P
Montet
M P
MP
Ray-Gueniot
S
S
Villard
L
L
Bavai
C
C
Meyrand
A
A
Mazuy
C
C
Atrache
V
V
D018829:Adhesins, Bacterial; D000483:Alleles; D000818:Animals; D000831:Animals, Newborn; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000032:analysis / Q000235:genetics; D002352:Carrier Proteins; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D003470:Culture Media; D004927:Escherichia coli Infections / Q000662:veterinary; D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification*; D029968:Escherichia coli Proteins; D005243:Feces / Q000382:microbiology*; D005966:Glucuronidase / Q000378:metabolism; D007158:Immunologic Techniques; D018189:Immunomagnetic Separation; D010957:Plasmids; D016133:Polymerase Chain Reaction; D022641:Shiga Toxin 2; D013012:Sorbitol / Q000378:metabolism
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001427:Bacterial Toxins; D002352:Carrier Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D022641:Shiga Toxin 2; C073819:eaeA protein, E coli; D013012:Sorbitol; D005966:Glucuronidase