Hyperspectral Imaging for Detecting Pathogens Grown on Agar Plates

Authors: Yoon, Seung-Chul; Lawrence, Kurt; Siragusa, Gregory; Line, John; Park, Bosoon; Windham, William

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 8/17/2007
Publication Date: 9/25/2007
Citation: Yoon, S.C., Lawrence, K.C., Siragusa, G.R., Line, J.E., Park, B., Windham, W.R. 2007. Hyperspectral Imaging for Detecting Pathogens Grown on Agar Plates. Proceedings of SPIE 6761; 10-11 Sept. 2007, Boston MA.

Interpretive Summary: Campylobacter is the leading foodborne pathogen causing diarrhea illness in the US and worldwide. Detection and identification of Campylobacters obtained from food samples like chickens involve time-consuming or complicated laboratory tests such as culturing on agar plates and genetic tests. Direct culturing on agar plates has been known as an effective method to isolate and enumerate Campylobacters; however, distinguishing Campylobacters from non-Campylobacter contaminants that frequently grow on many existing agars is difficult. This research is about the development of an imaging technique using a hyperspectral camera to detect and identify Campylobacter and non-Campylobacter colonies grown on Petri dishes. A classification algorithm was developed to locate and identify Campylobacters, non-Campylobacter contaminants, and background agars with 99.29% accuracy. The fully developed imaging system is expected to automatically locate and identify organisms grown on Petri dishes and has a potential to be expanded to detect other pathogens like E-coli and Salmonella grown on agar media. This research may also contribute to build a spectral library of Campylobacter and non-Campylobacter organisms.

Technical Abstract: This paper is concerned with the development of a hyperspectral imaging technique for detecting and identifying one of the most common foodborne pathogens, Campylobacter. Direct plating using agars is an effective tool for laboratory tests and analyses of microorganisms. The morphology (size, growth pattern, color, etc.) of colonies grown on agar plates has been widely used to tentatively differentiate organisms. However, it is sometimes difficult to differentiate target organisms like Campylobacters from other contaminants grown together on the same agar plates. A hyperspectral imaging system operating at the visible and near infrared (VNIR) spectral region from 400 nm to 900 nm was set up to measure spectral signatures of 17 different Campylobacter and non-Campylobacter subspecies. Protocols for culturing, imaging samples and for calibrating measured data were developed. The VNIR spectral library of all 17 organisms commonly encountered in poultry was established from calibrated hyperspectral images. A classification algorithm was developed to locate and identify Campylobacters, non-Campylobacter contaminants, and background agars with 99.29% accuracy. This research has a potential to be expanded to detect other pathogens grown on agar media.