Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2014
Publication Date: 5/1/2015
Publication URL: https://handle.nal.usda.gov/10113/60988
Citation: He, Y., Reed, S.A., Bhunia, A.K., Gehring, A.G., Nguyen, L.T., Irwin, P.L. 2015. Rapid identification and classification of Campylobacter spp. using laser optical scattering technology. Food Microbiology. 47:28-35.
Interpretive Summary: A harmful bacterium known as Campylobacter (mainly Campylobacter jejuni and Campylobacter coli), is a frequent contaminant of poultry products and sometimes unpasteurized milk, produce, and water. It is the third most frequent cause of bacterial foodborne illness in the United States. To prevent food-related illnesses and improve food safety, rapid and reliable detection of Campylobacter in food is required. Through a collaboration with scientists at Purdue University, we have developed a novel biosensor-based method called BARDOT (BActerial Rapid Detection using Optical scattering Technology) for high-throughput detection of Campylobacter in food. Many strains of Campylobacter were tested using the BARDOT instrument, and thus a laser-scattering image library was created. Equipped with the image library, BARDOT was able to automatically scan and classify a large number of C. jejuni and C. coli colonies on agar plates, and therefore differentiate them from other major foodborne pathogens including Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes. Application of BARDOT in real food samples was also demonstrated after using a filtration method to overcome the interferences from the food matrix and to help in isolating pure Campylobacter colonies on solid growth medium. Use of the BARDOT system will improve the ability to detect Campylobacter, and thus enhance food safety.
Technical Abstract: Campylobacter jejuni and C. coli are the two important species responsible for most of the Campylobacter infections in humans. Reliable isolation and detection of Campylobacter spp. from food samples are challenging due to the interferences from complex food substances and the fastidious growth requirements of this organism. In this study, a novel biosensor-based detection called BARDOT (BActerial Rapid Detection using Optical scattering Technology) was developed for high-throughput screening of Campylobacter colonies grown on an agar plate without disrupting the intact colonies. Image pattern characterization and principle component analysis (PCA) of 6900 bacterial colonies showed that the light scatter patterns of C. jejuni and C. coli were strikingly different from those of Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. Examination of a mixed culture of these microorganisms revealed 97.5% accuracy in differentiating Campylobacter from the other three major foodborne pathogens based on the similarity to the scatter patterns in an established library. The application of BARDOT in real food has been addressed through the analysis of Campylobacter spiked ground chicken and naturally contaminated fresh chicken pieces. Combined with real-time PCR verification, BARDOT was able to effectively isolate and detect C. jejuni and C. coli from chicken samples. Moreover, applying passive filtration instead of directly plating food samples facilitated the isolation of pure Campylobacter colonies from food, and therefore overcoming the interference of the food matrix on BARDOT analysis.