Title: Hyperspectral imaging for differentiating colonies of non-O157 shiga-toxin producing echerichia coli (STEC) serogroups on spread plates of pure cultures
Authors: Yoon SC, Windham WR, Ladely SR, Heitschmidt GW, Lawrence KC, Park B, Narang N, Cray Jr WC
Journal: J Near Infrared Spectrosc
Accepted date: 2013 Feb 20
Interpretive summary: Direct plating of microorganisms on solid agar media has been widely used for screening foodborne pathogens although it is laborious and time-consuming because directing plating involves manual selection of presumptive-positive colonies one-by-one for further confirmatory testing. The USDA ARS scientists have been developing new non-contact optical imaging technology, called hyperspectral imaging, for rapid presumptive positive screening of colonies grown on agar plates. This study reports research results involving model development for discriminating colonies of the “Big Six” non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups such as O26, O111, O45, O121, O103, and O145 on Rainbow agar plates using hyperspectral imaging. A set of prediction models were developed from 1,421 colonies on 24 hyperspectral images obtained from spread plates individually inoculated with pure non-O157 STEC cultures. The best overall mean classification accuracy of 95.06% was achieved by a prediction model that adopted a k-nearest neighbor classifier of principal component scores. The study showed the potential of hyperspectral imaging for objective, rapid and accurate screening of non-O157 STEC colonies.
Publication date: 2013 Mar
Related projects: Optical Detection of Food Safety and Food Defense Hazards