Adsorption of endogenous polyphenols relieves the inhibition by fruit juices and fresh produce of immuno-PCR detection of Escherichia coli O157 : H7

The immuno-polymerase chain reaction (PCR) approaches facilitate rapid (8 h ) detection of Escherichia coli O157:H7 in contaminated dairy products and ground beef samples with detection sensitivities approaching 1 colony formi ng unit (cfu) g(-1) ml(-1). However, no PCR products were obtained when the method was applied to identify E. coli O157.1-17 in tainted apple juice. E nzyme-linked immune-assay (ELISA) results suggested non-specific binding of endogenous polyphenols (ubiquitous in plant products) to antibodies presen t on the surface of the immunobeads, making the latter unavailable for capt uring the target bacteria. Treatment of the test sample, prior to IMS, with a synthetic fining agent, polyvinylpyrrolidone, restored the full function and sensitivity of the immuno-PCR. The study demonstrates the suitability of the improved method as a generic strategy for rapid screening of fruit j uices and plant produce for E. coli O157:H7. (C) 1999 Federation of Europea n Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.