P3-123 Occurrence of Listeria spp. and Characterization of Listeria monocytogenes from a Fish Processing Facility in British Columbia, Canada

Wednesday, August 6, 2014
Exhibit Hall D (Indiana Convention Center)
Keely Johnston, University of British Columbia, Vancouver, Canada
Ewa Wałecka-Zacharska, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
Jessica Chen, University of British Columbia, Vancouver, Canada
Kevin Allen, University of British Columbia, Vancouver, Canada
Introduction: Listeria monocytogenes is a foodborne pathogen, which can cause a severe disease, listeriosis, in at-risk populations. A recent survey of ready-to-eat (RTE) foods and production environments in British Columbia (BC) detected L. monocytogenes in fish facilities and in RTE fish products destined for market. Given strict regulations pertaining to L. monocytogenes in RTE foods, L. monocytogenes contamination presents a challenge for BC RTE fish processors.

Purpose: To determine the occurrence of Listeria spp., including L. monocytogenes, in a BC RTE fish processing plant and characterize recovered L. monocytogenes genetically and phenotypically.

Methods: Environmental samples (n = 1748) were collected over a one-year period from a RTE fish processing plant in BC and were subjected to Health Canada standard procedures MFHPB-29 or MFHPB-30 for detection and isolation of Listeria spp. and L. monocytogenes. L. monocytogenes isolates (n = 14) were subsequently characterized by lineage-typing ASO-PCR, assessed for frequency of mutation by plating isolates on Brain Heart Infusion Agar with rifampicin (100μg/ml), and screened by PCR for genetic markers that may contribute to increased persistence (e.g., LGI1 and bcrABC).

Results: Listeria spp. and L. monocytogenes were recovered in 2.6% and 1.0% of samples, respectively. Cutting boards and raw fish surfaces yielded 93% of the samples positive for L. monocytogenes. Lineage-typing revealed that the majority of L. monocytogenes recovered belong to Lineage I (60%), with the remainder belonging to Lineage II. The frequency of mutations between lineages was not significantly different (P = 0.07) and LGI1 and bcrABC were absent in all screened isolates.

Significance: This research provides improved understanding of Listeria spp. and L. monocytogenes prevalence in a BC RTE fish processing facility coupled with details regarding genetic and phenotypic attributes of recovered L. monocytogenes. This knowledge will help processors tailor their L. monocytogenes control strategies to minimize contamination of products entering the food chain.