In 2015, scientists from BIOTEC and Queen’s University Belfast reported the development of immunobead array method to simultaneously detect three important foodborne pathogens, Campylobacter jejuni, Listeria monocytogenes, and Salmonella spp., for application in routine food testing. While the sensitivities of detection of this technique were better than a sandwich ELISA method when using the same sets of antibodies, the limits of detection were not low enough to detect the pathogens at the concentrations required by food safety regulations. To make this developed technique applicable for food safety testing, enrichment steps to increase bacterial numbers are required and validation with actual food samples must be undertaken.
Scientists evaluated commercial enrichment culture media to ensure sufficient numbers of pathogens were present at time of testing and validated the immunobead array by testing chicken products. The findings showed that the immunobead array method was capable of detecting as low as 1 CFU of the pathogens spiked in the culture media after being cultured for 24 h for all three pathogens. The immunobead array method was evaluated for its pathogen detection capabilities in ready-to-eat (RTE) and ready-to-cook (RTC) chicken samples and proven to be able to detect as low as 1 CFU of the pathogens spiked in the food samples after being cultured for 24 h in the case of Salmonella spp., and L. monocytogenes and 48 h in the case of C. jejuni. The method was subsequently validated with three types of chicken products -- RTE, RTC and raw chicken -- and was found to give the same results as the conventional plating method. These findings demonstrated that the previously developed immunobead array method could be used for actual food testing with minimal enrichment period of only 52 h, whereas the conventional ISO protocols for the same pathogens take 90–144 h. The technique is an inexpensive, rapid and simple method for the food testing.
Ref: Charlermroj, R., Makornwattana, M.,Grant, I.R., Elliott, C.T. and Karoonuthaisiri, N. (2016). Validation of a high-throughput immunobead array technique for multiplex detection of three foodborne pathogens in chicken products. International Journal of Food Microbiology, 224, 47-54.
Posted on 23 March 2016.