Gold-immunochromatography assay for Escherichia coli O157

Objective The present study was conducted to establish a sensitive,rapid,and convenient gold immunochromatography assay (GICA) by using monoclonal anti-E.coli O157 for the detection of E.coli O157. Methods The trisodium citrate reduction method was used to prepare colloidal golds,which were coupled with monoclonal anti-E.coli O157. These antibodies were immobilized on nitrocellulose (N.C) membrane to prepare a GICA card device. The gold-antibodies (Au-Ab) conjugates reacted with E.coli 0157 in the samples and migrated up the N.C membrane to produce a optical red strip. Results The sensitivity of GICA was 105 cfu/ml. 1750 different food and stool samples were detected by GICA for E.coli 0157 and 43 samples were found to be GICA positive. E.coli O157 were isolated from 29 of the 43 positive samples with 12 C.freundii identified in the remaining 14 positive samples. Conclusion GICA is a specific,rapid and simple assay for the detection of E.coli O157,applicable to performing the tests in centers for disease control and prevention and clinical laboratories at various levels.