Pa. Chapman et al., A COMPARISON OF IMMUNOMAGNETIC SEPARATION AND DIRECT CULTURE FOR THE ISOLATION OF VEROCYTOTOXIN-PRODUCING ESCHERICHIA-COLI O157 FROM BOVINEFECES, Journal of Medical Microbiology, 40(6), 1994, pp. 424-427
Enhrichment culture (EC) in modified buffered peptone water followed b
y immunomagnetic separation (IMS) with magnetic beads coated with an a
ntibody against Escherichia coli O157 (Dynabeads anti-E. coli O157; Dy
nal, Oslo) was compared with direct culture on cefixime rhamnose sorbi
tol 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 diff
erent strains of E. coli O157, EC-IMS was c. 100-fold more sensitive f
or detection of the organism than direct culture on either medium. Dur
ing 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 I
MS (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 b
y 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.