Automated Multistep Lateral Flow Immunoassay Using a Smartphone for the Quantification of Foodborne Bacteria from Fresh Lettuce

Foodborne illnesses are one of the most severe and prevalent health problems in the world. Thus, achieving the rapid and accurate identification of foodborne pathogens is important. This study presents an automatic device to perform a multistep immunoassay on a lateral flow immunoassay strip to detect foodborne pathogens from fresh lettuce. The device is automatically operated using a smartphone application that we developed, which allows users to quantify the detection results. In this study, we characterize the device's limit of detection and demonstrate the detection and quantification of Escherichia coli O157:H7 from contaminated lettuce. We then compare the quantified result to that calculated by counting colonies from agar plates. The device is capable of detecting contamination in lettuces that have as low as 5 x 10(4) Escherichia coli O157:H7 per 10 g.