Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2019
Publication Date: 2/7/2020
Citation: Eady, M.B., Park, B., Hinton Jr, A. 2020. Rapid identification of Campylobacter species cultured under aerobic incubation using hyperspectral microscope imaging. Journal of Food Protection. https://doi.org/10.4315/0362-028X.JFP-19-311.
Interpretive Summary: Campylobacter is one of the world’s leading causes of foodborne illness and a federally regulated pathogenic organism in the poultry industry. During foodborne disease outbreaks, Campylobacter can be difficult to grow in a laboratory and requires an extended period of incubation. Hyperspectral microscope images (HMI) have been proposed for early and rapid detection of foodborne pathogens. Recently, a new aerobic growth media for Campylobacter has been developed for incubating the pathogen without a need for modified atmospheres. Here, the objective was to combine HMI technology with the novel aerobic growth media for Campylobacter for 24 h detection. Three Campylobacter species were grown (C. coli, C. fetus, and C. jejuni) on traditional Campylobacter agar with modified atmospheres for 48 h and on the novel growth media for 24 h and 48 h. Results showed that bacteria grown under the traditional method could differentiate between species at a 98% accuracy, while HMI data obtained from the 24 and 48 h aerobically grown bacteria had less than a 5% change in accuracy, suggesting that HMI paired with a novel aerobic growth media at 24 h can have similar classification results to the traditionally grown Campylobacter.
Technical Abstract: Campylobacter is an organism of concern for food safety, as it is one of the leading causes of foodborne bacterial gastroenteritis. The pathogen can be found in broiler chickens with the level of contamination of processed poultry regulated by federal agency guidelines. Traditional methods for detecting and isolating the bacterium from broiler chicken carcasses requires time, expensive reagents, and artificially generated microaerophilic atmospheres. Recently, a novel media that simplifies the procedure and reduces the expense of culturing Campylobacter has been described. Campylobacter can be grown in the medium in containers that are incubated aerobically. Furthermore, hyperspectral microscope imaging (HMI) has been proposed for early and rapid detection of pathogens at the cellular level. Here, the objective was to utilize HMI to characterize and compare differences in Campylobacter cultures grown under artificially produced microaerobic atmospheres and cultures grown in novel medium. HMI of three Campylobacter species were collected from bacteria cultured microaerophilically at 48 h and aerobically at 24 and 48 h, and a quadratic discriminant analysis was applied to characterize the bacteria. Microaerobically cultured bacteria were detected with a 98.7% accuracy, while cultures grown in novel medium resulted in a slight reduction in accuracy of -4.8% and -3.2% for 24 and 48 h, respectfully. The Mahalanobis distance, a multivariate distance metric was applied to quantify species variability at all three treatments, finding that across all species and treatments with very little cluster variation present, ranging from 4.22 to 4.42. Cultures incubated in the novel medium for 24 h showed similar species classification ability and spectral consistency to those cells grown for 48 h under microaerobic conditions.