Detection of Enterotoxigenic Escherichia coil in Foods by DNA Colony Hybridization

A DNA colony hybridization procedure was used to identify and enumerate a heat-labile toxin-producing strain of Escherichia coli (H10407) in various types of foods. Foods were seeded with H10407 cells and examined by DNA hybridization on nitrocellulose filters with 32P- labeled heat-labile toxin gene fragments. The number of cells recovered on plate count agar and eosine methylene blue agar was compared. With nitrocellulose filters, recoveries were about 81% on plate count agar and about 76% on eosine methylene blue agar. No significant differences in recovery were observed with ten different food types.