title: A comparison of immunomagnetic separation and direct culture for the isolation of verocytotoxin-producing Escherichia coli O157 from bovine faeces.
abstract: 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.
authors.affiliation: Public Health Labortory, Sheffield.
authors.forename: P A
authors.initials: PA
authors.lastname: Chapman
authors.forename: D J
authors.initials: DJ
authors.lastname: Wright
authors.forename: C A
authors.initials: CA
authors.lastname: Siddons
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis*; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D003603:Cytotoxins / Q000096:biosynthesis*; D004768:Enterotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000302:isolation & purification* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D005243:Feces / Q000382:microbiology*; D005260:Female; D018189:Immunomagnetic Separation; D022622:Shiga Toxin 1
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D004768:Enterotoxins; D022622:Shiga Toxin 1