Rapid large-volume concentration for increased detection of Escherichia coli O157:H7 and Listeria monocytogenes in lettuce wash water generated at commercial facilities

Occurrence and Accumulation of Human Enteric Viruses and Phages in Process Water from the Fresh Produce Industry

“…The occurrence of potentially infectious enteric viruses in PW used by the fresh produce industry is likely possible, and thus, it must be closely examined. Several factors must be considered to address this issue: (i) Relatively low levels of enteric viruses introduced will be randomly distributed into large volumes of water and may not be detectable using protocols indicating small volume collection; (ii) sampling points in commercial facilities are critical for pathogen detection [11]; (iii) molecular-based methods, currently used for enteric virus detection in food [12] cannot discriminate between inactivated and potentially infectious enteric viruses; (iv) organic fresh produce market, limiting the use of sanitizers, has tremendously increased in the last years and the food safety perception of consumers must be assured.…”

Genomic analysis of high copy-number sequences for the targeted detection of Listeria species using a flow-through surveillance system

“…The specific binding in the capture column was achieved by the use of DNA aptamers (Suh et al 2014 ; Suh and Jaykus 2013 ), which are oligonucleotide molecules that bind to specific epitopes that are presented on the bacterial cell surface and have been proposed for pathogen capture as a low-cost alternative to antibodies (Teng et al 2016 ). The use of DNA aptamers enabled Listeria cell capturing without the need for small particle filtering, which can be subject to membrane fouling when isolating bacterial pathogens from food and environmental samples (Ferrari et al 2019 ; Kearns et al 2019 ; Li et al 2013 ; Zhang et al 2018 ). To improve the capturing of the Listeria cells with the DNA aptamer (Suh et al 2014 ; Suh and Jaykus 2013 ), additional sequences, a spacer sequence for aptamer extension and a tether sequence for aptamer surface attachment (see Material and Methods)(Quiñones et al 2020 ), were designed and added to the aptamer to enable binding to the capture column and prevent the aggregation of the aptamer for efficient release of the target bacterial cell from the aptamer (Medin et al 2020 ; Quiñones et al 2020 ).…”

“…To improve the detection of pathogens from samples, various reports have documented on using microfiltration to reduce large samples to a small volume (Li et al 2013 ). However, small particle filtering can be subject to membrane fouling when isolating bacterial pathogens from food and environmental samples, resulting in reduced levels of detection sensitivities (Kearns et al 2019 ; Li et al 2013 ; Zhang et al 2018 ). In the present study, the flow-through system did not use membrane filtration but instead used an adaptation of depth filtering, a processing stage previously used for preventing filter clogging (Murakami 2012 ), followed by the use of an aptamer-functionalized column for successfully capturing and concentrating the targeted Listeria cells from samples.…”

“…The findings from the present study indicated the flow-through system accurately detected Listeria cells at cell concentrations that were 15 times below the infectious dose. Due to the non-uniform distribution of microorganisms, current methods employing small sample sizes can result in undetected pathogens, and the lack of accurate detection of the tested foodborne pathogen can lead to subsequent outbreaks (Capobianco et al 2021 ; Kearns et al 2019 ). To continue to meet the needs of the food safety industry and regulators (Kaplan et al 2014 ; Kuiper and Paoletti 2015 ), further research is aimed at optimizing the high binding efficiency of the flow-through system, documented in the present study, to optimize the rapid, low-cost capture of Listeria species using increased sample size over a range of environmental and food samples.…”