Developmental evaluation of a Listeria-specific magnetic-separation method (CBD-MS) and a combined CBD-MS/MDA approach for sequencing Listeria monocytogenes in food

Funding period: 2021-2024
Lead: Calvin Lau
Total GRDI funding: $125,000

Listeria monocytogenes is a significant foodborne pathogen and the primary causative agent of listeriosis. To mitigate this food safety hazard, CFIA relies on robust and sensitive microbiological testing methods to carry out routine inspection/monitoring in high-risk food samples. At present, the majority of the Health Canada-endorsed reference methods for L. monocytogenes require lengthy enrichment culturing step(s). With the goal of developing tools that can be easily employed by frontline laboratory analysts as a parallel/alternative strategy to expedite the identification and characterization of L. monocytogenes, this project aims at exploring a "target-centric" approach to more efficiently recover this foodborne microorganism and its genomic content. It aims to establish and evaluate an alternative, non-antibody based magnetic separation method, namely, CBD-MS to selectively capture L. monocytogenes cells from food samples that undergo the MFHPB-30 culture enrichment procedures. An innovative workflow that combines (i) culture-based selective enrichment, (ii) high-affinity target-immobilization and capturing via CBD-MS, and (iii) single-tube genome amplification through isothermal multiple-displacement amplification (MDA) will also be devised. Such workflow should generate sufficient genomic material of the L. monocytogenes target from partially-/fully- enriched samples to allow for high-throughput sequencing and PCR/qPCR-based rapid screening. This will facilitate quicker turnaround time for strain identification and matching against outbreak and/or clinical isolates.