A novel lateral flow immunoassay for the rapid detection of Escherichia coli O157

Research Assistant
Department of Veterinary and Biomedical Sciences
Penn State University
204 Wartek Lab, University Park, PA 16802 USA

Jinliang Wang 1,2, Robab Katani1, Lingling Li1, Vivek Kapur1, Chitrita DebRoy1

Escherichia coli O157:H7 (E. coli O157) was first identified as etiological agent of bloody diarrhea in the early 1980s and has since been recognized worldwide as a cause of food- and waterborne infectious diseases. The infection may lead to the development of hemolytic uremic syndrome (HUS), an infection sequelae characterized by hemolysis and renal failure, which can lead to long-term kidney damage or fatal outcome. We have developed a novel rapid lateral flow immunoassay (LFI) one-step strip test based on the nano colloidal gold-conjugated "lipid A" polyclonal antibody to specifically detect E.coli O157. The test is rapid, accurate and simple and does not require sophisticated equipment or trained personnel for detecting the pathogen. The detected maximum absorbent wavelength for the gold nanoparticles (diameter of 13nm) was found to be 518nm scanned using a DU-800 spectrophotometer. Compared to ELISA testing, LFI showed higher sensitivity at 104 CFU/ml, and high specificity, when compared with tested non-O157 strains. The optimal concentration for the development of LFI of gold-labeled lipid A polyclonal antibody was found to be 12 μg/ml. The LFI test may be used for screening E. coli O157 in food, water, and the environment. The assay provides a conceptual framework that can be adapted for the development of similar tests for the rapid detection of other serogroups of E.coli that are considered as adulterant in meat by Food Safety and Inspections Services of USDA.

1Department of Veterinary and Biomedical Sciences, The Pennsylvania State University,
University Park, PA

2Shandong Binzhou Animal Science&Veterinary Medicine Academy, Binzhou 256600, China