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. 2022 Mar 20;11(6):886.
doi: 10.3390/foods11060886.

Evaluation of the Persistence and Characterization of Listeria monocytogenes in Foodservice Operations

Magaly Toro  1 , Jessica Williams-Vergara  1 , Camila Solar  1 , Ana María Quesille-Villalobos  1 , Hee Jin Kwon  2   3 , Paola Navarrete  1 , Jianghong Meng  2   3 , Yi Chen  4 , Angélica Reyes-Jara  1
Affiliations

Evaluation of the Persistence and Characterization of Listeria monocytogenes in Foodservice Operations

Magaly Toro et al. Foods. .

Abstract

Listeria monocytogenes is a major foodborne pathogen that can contaminate food products and colonize food-producing facilities. Foodservice operations (FSOp) are frequently responsible for foodborne outbreaks due to food safety practices failures. We investigated the presence of and characterized L. monocytogenes from two FSOp (cafeterias) distributing ready-to-eat meals and verified FSOp's compliance with good manufacturing practices (GMP). Two facilities (FSOp-A and FSOp-B) were visited three times each over 5 months. We sampled foods, ingredients, and surfaces for microbiological analysis, and L. monocytogenes isolates were characterized by phylogenetic analyses and phenotypic characteristics. GMP audits were performed in the first and third visits. A ready-to-eat salad (FSOp-A) and a frozen ingredient (FSOp-B) were contaminated with L. monocytogenes, which was also detected on Zone 3 surfaces (floor, drains, and a boot cover). The phylogenetic analysis demonstrated that FSOp-B had persistent L. monocytogenes strains, but environmental isolates were not closely related to food or ingredient isolates. GMP audits showed that both operations worked under "fair" conditions, and "facilities and equipment" was the section with the least compliances. The presence of L. monocytogenes in the environment and GMP failures could promote food contamination with this pathogen, presenting a risk to consumers.

Keywords: GMP; Listeria monocytogenes; biofilm; foodservice operations; genomic analysis; quaternary ammonium resistance.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Visits scheme to FSOp-A and FSOp-B.
Figure 2
Figure 2
Neighbor-joining phylogeny of isolates based on SNP of L. monocytogenes by serogroup (a) IVb and (b) IIb. The circle color indicates isolation source: Red = drain; green = food; black = floor; and blue = boot cover.
Figure 3
Figure 3
L. monocytogenes biofilm formation. Grey bars represent FSOp-A isolates, and black bars are FSOp-B isolates. L. monocytogenes EGD-e strain (serotype 1/2a) was used as a control.
Figure 4
Figure 4
Audit results. Percent of compliant for each section analyzed. FSOp-A: (a) first audit (visit 1) and (b) second audit (visit 3). FSOp-B: (c) first audit (visit 1) and (d) second audit (visit 3).
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