Print to detect: a rapid and ultrasensitive phage-based dipstick assay for foodborne pathogens
Citation
Anany, H., Brovko, L., El Dougdoug, N.K., Sohar, J., Fenn, H., Alasiri, N., Jabrane, T., Mangin, P., Monsur Ali, M., Kannan, B., Filipe, C.D.M., Griffiths, M.W. (2018). Print to detect: a rapid and ultrasensitive phage-based dipstick assay for foodborne pathogens. Analytical and Bioanalytical Chemistry, [online] 410(4), 1217-1230. http://dx.doi.org/10.1007/s00216-017-0597-y
Plain language summary
The availability of a rapid, sensitive and specific detection method of foodborne pathogens is vital to ensure a safe and secure food supply. Bacteriophages (bacteria eaters) would be a promising detection and biocontrol tool of foodborne pathogens due to their ability to infect and kill bacteria in a strain-specific manor. This research investigated a phage-based biosensor for the detection of various foodborne pathogens in food matrices. Bioactive paper with bacteriophages applied by coating or printing was produced. Conditions such as paper type and bio-ink composition were optimized to preserve biological activity (infectivity) of bacteriophages. The phage-based bioactive papers actively lysed their target bacteria and retained this antibacterial activity for up to 1 month when stored at room temperature and 80% relative humidity. Strips of bioactive phage dipsticks were used to capture and infect E. coli O157:H7, E. coli O45:H2 and Salmonella Newport in spinach, ground beef and chicken homogenates, respectively. The assay detected 10 - 50 colony forming units per gram in 8 hours, which is the duration of a typical work shift in an industrial setting. This detection method is rapid, cost-effective and can be applied to a broad range of bacterial foodborne pathogens.
Abstract
Foodborne pathogens are a burden to the economy and a constant threat to public health. The ability to rapidly detect the presence of foodborne pathogens is a vital component of any strategy towards establishing a safe and secure food supply chain. Bacteriophages (phages) are viruses capable of infecting and replicating within bacteria in a strain-specific manner. The ubiquitous and selective nature of phages makes them ideal for the detection and biocontrol of bacteria. Therefore, the objective of this research was to develop and test a phage-based paper dipstick biosensor for the detection of various foodborne pathogens in food matrices. The first step was to identify the best method for immobilizing phages on paper such that their biological activity (infectivity) was preserved. It was found that piezoelectric inkjet printing resulted in lower loss of phage infectivity when compared with other printing methods (namely gravure and blade coating) and that ColorLok paper was ideally suited to create functional sensors. The phage-based bioactive papers developed with use of piezoelectric inkjet printing actively lysed their target bacteria and retained this antibacterial activity for up to 1 week when stored at room temperature and 80% relative humidity. These bioactive paper strips in combination with quantitative real-time PCR were used for quantitative determination of target bacteria in broth and food matrices. A phage dipstick was used to capture and infect Escherichia coli O157:H7, E. coli O45:H2, and Salmonella Newport in spinach, ground beef and chicken homogenates, respectively, and quantitative real-time PCR was used to detect the progeny phages. A detection limit of 10–50 colony-forming units per millilitre was demonstrated with a total assay time of 8 h, which was the duration of a typical work shift in an industrial setting. This detection method is rapid and cost-effective, and may potentially be applied to a broad range of bacterial foodborne pathogens. [Figure not available: see fulltext.].