A comparison of immunomagnetic separation and direct culture for the isolation of verocytotoxin-producing Escherichia coli O157 from bovine faeces

J Med Microbiol. 1994 Jun;40(6):424-7. doi: 10.1099/00222615-40-6-424.


Enrichment culture (EC) in modified buffered peptone water followed by immunomagnetic separation (IMS) with magnetic beads coated with an antibody against Escherichia coli O157 (Dynabeads anti-E. coli O157; Dynal, Oslo) was compared with direct culture on cefixime rhamnose sorbitol MacConkey agar (CR-SMAC) and cefixime tellurite sorbitol MacConkey agar (CT-SMAC) for the isolation of E. coli O157 from bovine faeces. When used to examine bovine faecal suspensions inoculated with 12 different strains of E. coli O157, EC-IMS was c. 100-fold more sensitive for detection of the organism than direct culture on either medium. During monitoring of a dairy herd, E. coli O157 was isolated from 84 (8.2%) of 1024 rectal swabs taken from cattle over a 4-month period; 23 (27.4% of the 84 strains were isolated by both direct culture and IMS (15 of the 23 were isolated on both media, five on CT-SMAC only and three on CR-SMAC only), whereas 61 (72.6%) strains were isolated by IMS only. IMS is a sensitive and simple technique for the isolation of E. coli O157 from bovine faecal samples and should prove useful in elucidating further the epidemiology of this organism.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Bacterial Toxins / biosynthesis*
  • Cattle
  • Cattle Diseases / microbiology
  • Cytotoxins / biosynthesis*
  • Enterotoxins / biosynthesis*
  • Escherichia coli / isolation & purification*
  • Escherichia coli / metabolism
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / veterinary
  • Feces / microbiology*
  • Female
  • Immunomagnetic Separation
  • Shiga Toxin 1


  • Bacterial Toxins
  • Cytotoxins
  • Enterotoxins
  • Shiga Toxin 1