Disinfection of Foodborne Bacteria using the Contamination Sanitization Inspection and Disinfection (CSI-D) Device

Foodborne pathogens, including Escherichia coli, Salmonella enterica, and Listeria monocytogenes, are major causes of gastrointestinal disease globally. The Contamination Sanitization Inspection and Disinfection (CSI-D) device is a new handheld fluorescence-based imaging system designed to disinfect food contact surfaces contaminated with microorganisms using ultraviolet-C (UVC) illumination. This study aimed to determine the optimal parameters for the disinfection of foodborne bacteria using the CSI-D device. The following bacterial strains were tested: generic E. coli; enterohemorrhagic E. coli (EHEC) O157:H7; enterotoxigenic E. coli (ETEC) O78:H11; S. enterica serotypes Enteritidis, Newport, Typhimurium, and Javiana; and L. monocytogenes serotypes 1/2a, 1/2b, and 4b. Each bacterial strain was spread-plated on non-selective agar and exposed to high-intensity (10 mW/cm2) or low-intensity (5 mW/cm2) UVC for 1 s, 3 s, or 5 s or were not exposed to UVC (control). The plates were then incubated overnight at 37℃ and the resulting colonies were counted. Three trials for each bacterial strain were conducted on separate days. The average of the trials showed that exposure time of 3-5 s at either intensity (high: 10 mW/cm2 or low: 5 mW/cm2) resulted in effective and consistent inhibition of E. col, S. enterica, and L. monocytogenes growth. The minimum reduction at 3 s and 5 s exposure for both intensities was 99.95-100% for E. coli, 98.36-100% for S. enterica, and 99.24-100% for L. monocytogenes. The 1 s exposure time resulted in lower efficiency in reducing bacterial growth, with survival rates of 0.48-6.95% for E. coli, 0.29-17.40% for S. enterica, and 1.95-31.8% for L. monocytogenes. The results of this study show that, in pure culture conditions, exposure to UVC with the CSI-D device for at least 3 s is required to achieve 98-100% reduction of E. coli, S. enterica, and L. monocytogenes