Assessment of Sanitation Practices for the Control of Listeria monocytogenes at Small and Very Small Ready-to-Eat Meat and Poultry Processors

Listeria spp., Listeria monocytogenes

Listeriosis is a disease caused by L. monocytogenes, a relevant microorganism as a causative agent of foodborne diseases - FBD. This study aimed to evaluate the distribution of Listeria spp., and L. monocytogenes in different production areas in two small plants (A and B) and two micro-food processing plants (C and D) producing meat derivatives, located in different cities of Colombia. The methodology implemented was i. The analysis of sampling points is based on a harmonised tool. ii. Four samplings in each production plant between 2019 and 2020. iii. Isolation and identification of microorganisms through conventional microbiology, a semi-automated system, molecular serotyping and clonal characterisation by ERIC-PCR. L. monocytogenes frequency in the production plants belonging to the study ranged between 5.9 and 28.6 %; for Listeria spp., plants A and D had isolated, plant A had the highest proportion, while for L. monocytogenes geno-serotypes found were: 1/2a, 1/2c, 4a-4c, 4b, 4d - 4e, with geno-serotype 4b as the most frequent. Furthermore, possible persistent isolates were detected in plant C as the feasible sources of contamination, based on failures in flow management, raw material contaminated with L. monocytogenes, lack of standardised cooking processes and transfer of the microorganism through equipment and surfaces. Finally, in three of the four production plants assayed, L. monocytogenes or Listeria spp. were present in the packaging area in some of the samples taken during the study, which calls for increased and frequent monitoring, as well as constant technical support for the control of L. monocytogenes in micro and small-scale production plants.

Intensive Environmental Sampling and Whole Genome Sequence-based Characterization of Listeria in Small- and Medium-sized Dairy Facilities Reveal Opportunities for Simplified and Size-appropriate Environmental Monitoring Strategies

Small- and medium-sized dairy processing facilities (SMDFs) may face unique challenges with respect to controlling Listeria in their processing environments, e.g., due to limited resources. The aim of this study was to implement and evaluate environmental monitoring programs (EMPs) for Listeria control in eight SMDFs in a ∼1-year longitudinal study; this included a comparison of pre-operation (i.e., after cleaning and sanitation and prior to production) and mid-operation (i.e., at least 4 h into production) sampling strategies. Among 2,072 environmental sponge samples collected across all facilities, 272 (13%) were positive for Listeria. Listeria prevalence among pre- and mid-operation samples (15% and 17%, respectively), was not significantly different. Whole genome sequencing (WGS) performed on select isolates to characterize Listeria persistence patterns revealed repeated isolation of closely related Listeria isolates (i.e., ≤20 high-quality single nucleotide polymorphism [hqSNP] differences) in 5/8 facilities over >6 months, suggesting Listeria persistence and/or reintroduction was relatively common among the SMDFs evaluated here. WGS furthermore showed that for 41 sites where samples collected pre- and mid-operation were positive for Listeria, Listeria isolates obtained were highly related (i.e., ≤10 hqSNP differences), suggesting that pre-operation sampling alone may be sufficient and more effective for detecting sites of Listeria persistence. Importantly, our data also showed that only 1/8 of facilities showed a significant decrease in Listeria prevalence over 1 year, indicating continued challenges with Listeria control in at least some SMDFs. We conclude that options for simplified Listeria EMPs (e.g., with a focus on pre-operation sampling, which allows for more rapid identification of likely persistence sites) may be valuable for improved Listeria control in SMDFs.

Effect of Sodium Nitrite, Nisin and Lactic Acid on the Prevalence and Antibiotic Resistance Patterns of Listeria monocytogenes Naturally Present in Poultry

The impact of treating minced chicken meat with sodium nitrite (SN, 100 ppm), nisin (Ni, 10 ppm) and lactic acid (LA, 3000 ppm) on the levels of some microbial groups indicating hygiene quality were investigated. Specifically, aerobic plate counts and culture-based counts of psychrotrophic microorganisms and enterobacteria were obtained. Additionally, the prevalence of Listeria monocytogenes and the resistance of 245 isolates from this bacterium to 15 antibiotics were documented. L. monocytogenes was isolated using the ISO 11290-1:2017 method and confirmed with polymerase chain reaction using the lmo1030 gene. Antibiotic resistance was established using the disc diffusion technique (EUCAST and CLSI criteria). Twenty-four hours after treatment, the microbial load (log10 cfu/g) was reduced (p < 0.05) relative to controls in those samples treated with LA, with counts of 5.51 ± 1.05 (LA-treated samples) vs. 7.53 ± 1.02 (control) for APC, 5.59 ± 1.14 (LA) vs. 7.13 ± 1.07 (control) for psychrotrophic microorganisms and 2.33 ± 0.51 (LA) vs. 4.23 ± 0.88 (control) for enterobacteria. L. monocytogenes was detected in 70% (control samples), 60% (samples receiving SN), 65% (Ni) and 50% (LA) (p > 0.05) of samples. All strains showed resistance to multiple antimicrobials (between 3 and 12). In all, 225 isolates (91.8%) showed a multi-drug resistant (MDR) phenotype, and one isolate (0.4%) showed an extensively drug-resistant (XDR) phenotype. The mean number of resistances per strain was lower (p < 0.01) in the control samples, at 5.77 ± 1.22, than in those receiving treatment, at 6.39 ± 1.51. It is suggested that the use of food additives might increase the prevalence of resistance to antibiotics in L. monocytogenes, although additional studies would be necessary to verify this finding by analyzing a higher number of samples and different foodstuffs and by increasing the number of antimicrobial compounds and concentrations to be tested.

Review and Analysis of Tuna Recalls in the United States, 2002 through 2020

ABSTRACT

This review covers 18 years of voluntary recalls of tuna sold commercially in the United States. Recall information is a valuable indicator of failure to implement procedures for food safety. The voluntary recalls involve tuna that was fresh, frozen, processed, hermetically sealed, retorted in a shelf-stable pack (i.e., canned), and formulated into other tuna products. U.S. Food and Drug Administration regulations address the capture, processing, transportation, and sale of raw and processed seafood. These regulations include current good manufacturing practices, the Food Modernization Act, emergency permit controls, and guidelines for low-acid canned foods, seafood hazard analysis and critical control points, food labeling, and sanitary food transportation. Traceability and the food safety culture are important for successfully preventing or implementing recalls. The recalls themselves were separated into product treatment groups: uncooked products, canned shelf-stable products, and products in which tuna was used as an ingredient. The recalls were further categorized and summarized by reason or cause, such as biological and chemical contamination, undeclared ingredients, underprocessing, and foreign materials. The primary causes of recalls of the reviewed tuna products were (in order) Listeria monocytogenes, undeclared allergens, elevated histamine concentrations, and underprocessing of retorted tuna products. The recalls for elevated histamine concentrations primarily affected uncooked (raw) tuna. Recalls for Listeria contamination and the presence of undeclared allergens were primarily class I recalls, and recalls for elevated histamine concentrations and underprocessing were almost always assigned to the less serious recall class II.

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