Rapid enumeration of Escherichia coli in oysters by a quantitative PCR-ELISA

Direct enumeration of Escherichia coli from oysters was achieved using a po lymerase chain reaction (PCR) amplification of the lamB gene coupled with a n enzyme-linked immunosorbent assay (ELISA). Amplified PCR products generat ed using a digoxigenin-labelled primer were heat denatured before being qua ntified by an ELISA. A biotinylated probe immobilized onto streptavidin-coa ted microplates was used to capture the digoxigenin-labelled fragments that were detected with a peroxidase antidigoxigenin conjugate. Subsequent enzy mic conversion of substrate gave distinct absorbance differences when assay ing oyster samples containing E. coli in the range 10-10(5) cfu g(-1).