Title: Differentiation of big-six non-O157 shiga-toxin producing escherichia coli (STEC) on spread plates of mixed cultures using hyperspectral imaging
Authors: Yoon SC, Windham WR, Ladely SR, Heitschmidt GW, Lawrence KC, Park,B, Narang N, Cray Jr WC
Journal: J Food Meas Charact
Accepted date: 2013 Feb 22
Interpretive summary: Hyperspectral imaging is a non-destructive optical imaging technology that has been successfully used for solving many food safety problems such as foodborne pathogen and contaminant detection. The USDA ARS scientists have been developing hyperspectral imaging techniques for rapid screening of pathogenic colonies grown on agar plates. The “Big Six” non-O157 Shiga-toxin producing Escherichia coli (STEC) serogroups such as O26, O45, O103, O111, O121, and O145 are pathogenic bacteria causing foodborne disease and difficult to visually identify their colonies due to variability in STEC populations and/or the presence of background microflora. Considering the multi-day workflow of STEC detection and isolation, it is beneficial to reduce the time needed to identify presumptive-positive STEC colonies with a more objective and accurate tool. This study reports the results for hyperspectral image prediction models to identify the non-O157 STEC colonies when different STEC serogroups were mixed for plating. A total of six agar plates with mixed cultures and 12 plates with pure cultures as control were used for the study. The results showed 95% overall detection accuracy at pixel level and 97% at colony level. The developed technique was valid for predicting the colony identity from the mixed cultures. The results of this study confirmed the potential of the hyperspectral imaging technique to accurately identify the six non-O157 STEC serogroups when they grew together on the same agar plate.
Publication date: 2013 Jun
Related projects: Optical Detection of Food Safety and Food Defense Hazards