MLVA subtyping of Listeria monocytogenes isolates from meat products and meat processing plants

Nine groups of different retail ready-to-eat vacuum-packaged meat products from 10 Baltic meat processing plants were analyzed for presence and numbers of Listeria monocytogenes at the end of shelf life. A total of 38 (18%) of 211 samples tested positive for L. monocytogenes serotype 1/2a (88%) or 1/2c (12%). The prevalence of L. monocytogenes in cold-smoked, sliced, vacuum-packaged beef and pork products (42%) was significantly higher than in cooked, sliced, vacuum-packaged meat products (0.8%) (P < 0.001). Enumeration of L. monocytogenes showed that 84% of the positive samples contained <100 CFU/g upon expiry of product shelf life. The numbers of L. monocytogenes exceeded 100 CFU/g only in cold-smoked, sliced, vacuum-packaged beef products. Identical pulsed-field gel electrophoresis types were recovered from different production lots of cold-smoked vacuum-packaged beef and pork products produced by the same meat processing plant, demonstrating L. monocytogenes contamination as a recurrent problem within one meat processing plant.

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Complete Genome Sequences of Six Listeria monocytogenes Sequence Type 9 Isolates from Meat Processing Plants in Norway

Genome Announcements ◽

10.1128/genomea.00016-18 ◽

2018 ◽

Vol 6 (7) ◽

Cited By ~ 3

Author(s):

Annette Fagerlund ◽

Solveig Langsrud ◽

Birgitte Moen ◽

Even Heir ◽

Trond Møretrø

Keyword(s):

Listeria Monocytogenes ◽

Complete Genome ◽

Foodborne Pathogen ◽

Sequence Type ◽

Nanopore Sequencing ◽

Meat Processing ◽

Sequencing Data ◽

Genome Sequences ◽

Fatal Disease ◽

Processing Plants

ABSTRACT Listeria monocytogenes is a foodborne pathogen that causes the often-fatal disease listeriosis. We present here the complete genome sequences of six L. monocytogenes isolates of sequence type 9 (ST9) collected from two different meat processing facilities in Norway. The genomes were assembled using Illumina and Nanopore sequencing data.

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Microplate Fluorescence Assay for Measurement of the Ability of Strains of Listeria monocytogenes from Meat and Meat-Processing Plants To Adhere to Abiotic Surfaces

Applied and Environmental Microbiology ◽

10.1128/aem.00114-07 ◽

2007 ◽

Vol 73 (16) ◽

pp. 5235-5244 ◽

Cited By ~ 37

Author(s):

Rachel Gamble ◽

Peter M. Muriana

Keyword(s):

Listeria Monocytogenes ◽

Molecular Mechanisms ◽

Meat Processing ◽

Abiotic Surfaces ◽

Food Borne ◽

Environmental Surfaces ◽

Processing Plants ◽

Plate Counts ◽

Microplate Fluorescence Assay ◽

High Level

ABSTRACT Listeria monocytogenes is a significant food-borne pathogen that is capable of adhering to and producing biofilms on processing equipment, making it difficult to eliminate from meat-processing environments and allowing potential contamination of ready-to-eat (RTE) products. We devised a fluorescence-based microplate method for screening isolates of L. monocytogenes for the ability to adhere to abiotic surfaces. Strains of L. monocytogenes were incubated for 2 days at 30°C in 96-well microplates, and the plates were washed in a plate washer. The retained cells were incubated for 15 min at 25°C with 5,6-carboxyfluorescein diacetate and washed again, and then the fluorescence was read with a plate reader. Several enzymatic treatments (protease, lipase, and cellulase) were effective in releasing adherent cells from the microplates, and this process was used for quantitation on microbiological media. Strongly adherent strains of L. monocytogenes were identified that had 15,000-fold-higher levels of fluorescence and 100,000-fold-higher plate counts in attachment assays than weakly adherent strains. Strongly adherent strains of L. monocytogenes adhered equally well to four different substrates (glass, plastic, rubber, and stainless steel); showed high-level attachment on microplates at 10, 20, 30, and 40°C; and showed significant differences from weakly adherent strains when examined by scanning electron microscopy. A greater incidence of strong adherence was observed for strains isolated from RTE meats than for those isolated from environmental surfaces. Analysis of surface adherence among Listeria isolates from processing environments may provide a better understanding of the molecular mechanisms involved in attachment and suggest solutions to eliminate them from food-processing environments.

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Growth Temperatures of Ropy Slime-Producing Lactic Acid Bacteria

Journal of Food Protection ◽

10.4315/0362-028x-53.9.793 ◽

1990 ◽

Vol 53 (9) ◽

pp. 793-794 ◽

Cited By ~ 16

Author(s):

HANNU J. KORKEALA ◽

PIA M. MÄKELÄ ◽

HANNU L. SUOMINEN

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Growth Temperature ◽

Meat Products ◽

Maximum Growth ◽

Meat Processing ◽

Continuous Growth ◽

Maximum Growth Temperature ◽

Processing Plants ◽

Cooked Meat

The minimum, optimum, and maximum growth temperatures of ropy slime-producing lactic acid bacteria able to spoil vacuum-packed cooked meat products were determined on MRS-agar with temperature-gradient incubator GradiplateR W10. The minimum growth temperatures of slime-producing lactobacilli and Leuconostoc mesenteroides strain D1 were below −1°C and 4°C, respectively. The low minimum growth temperature allows these bacteria to compete with other bacteria in meat processing plants and in meat products causing ropiness problems. The maximum growth temperatures varied between 36.6–39.8°C. The maximum growth temperature of lactobacilli seemed to be an unstable character. Single lactobacilli colonies were able to grow above the actual maximum growth temperature, which is determined as the edge of continuous growth of the bacteria. The significance of this phenomenon needs further study.

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Preliminary results on prevalence and persistence of Listeria monocytogenes in different dairy and meat processing plants in Central Italy

International Journal of Infectious Diseases ◽

10.1016/j.ijid.2018.11.199 ◽

2019 ◽

Vol 79 ◽

pp. 78-79

Author(s):

S. Antoci ◽

V.A. Acciari ◽

V. Di Marzio ◽

I. Del Matto ◽

G. Centorotola ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Central Italy ◽

Meat Processing ◽

Preliminary Results ◽

Processing Plants

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Biofilms and Meat Safety: A Mini-Review

Journal of Food Protection ◽

10.4315/0362-028x.jfp-18-311 ◽

2018 ◽

Vol 82 (1) ◽

pp. 120-127 ◽

Cited By ~ 9

Author(s):

RONG WANG

Keyword(s):

Foodborne Pathogens ◽

Biofilm Formation ◽

Meat Products ◽

Meat Industry ◽

Meat Processing ◽

Complex Interactions ◽

Meat Safety ◽

Processing Plants ◽

High Event ◽

Multiple Species

ABSTRACT Biofilms are surface-attached microbial communities with distinct properties, which have a tremendous impact on public health and food safety. In the meat industry, biofilms remain a serious concern because many foodborne pathogens can form biofilms in areas at meat plants that are difficult to sanitize properly, and biofilm cells are more tolerant to sanitization than their planktonic counterparts. Furthermore, nearly all biofilms in commercial environments consist of multiple species of microorganisms, and the complex interactions within the community significantly influence the architecture, activity, and sanitizer tolerance of the biofilm society. This review focuses on the effect of microbial coexistence on mixed biofilm formation with foodborne pathogens of major concern in the fresh meat industry and their resultant sanitizer tolerance. The factors that would affect biofilm cell transfer from contact surfaces to meat products, one of the most common transmission routes that could lead to product contamination, are discussed as well. Available results from recent studies relevant to the meat industry, implying the potential role of bacterial persistence and biofilm formation in meat contamination, are reviewed in response to the pressing need to understand the mechanisms that cause “high event period” contamination at commercial meat processing plants. A better understanding of these events would help the industry to enhance strategies to prevent contamination and improve meat safety.

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Hygiene and Safety in the Meat Processing Environment from Butcher Shops: Microbiological Contamination and Listeria monocytogenes

Journal of Food Protection ◽

10.4315/0362-028x.jfp-15-482 ◽

2016 ◽

Vol 79 (4) ◽

pp. 628-634 ◽

Cited By ~ 5

Author(s):

DANILO AUGUSTO LOPES da SILVA ◽

MARIANE REZENDE DIAS ◽

MARCUS VINÍCIUS COUTINHO COSSI ◽

NATÁLIA PARMA AUGUSTO de CASTILHO ◽

ANDERSON CARLOS CAMARGO ◽

...

Keyword(s):

Listeria Monocytogenes ◽

Meat Products ◽

Meat Production ◽

Human Consumption ◽

Quality And Safety ◽

Meat Processing ◽

Microbiological Contamination ◽

Production Chain ◽

Indicator Microorganisms ◽

Butcher Shops

ABSTRACT The quality and safety of meat products can be estimated by assessing their contamination by hygiene indicator microorganisms and some foodborne pathogens, with Listeria monocytogenes as a major concern. To identify the main sources of microbiological contamination in the processing environment of three butcher shops, surface samples were obtained from the hands of employees, tables, knives, inside butcher displays, grinders, and meat tenderizers (24 samples per point). All samples were subjected to enumeration of hygiene indicator microorganisms and detection of L. monocytogenes, and the obtained isolates were characterized by their serogroups and virulence genes. The results demonstrated the absence of relevant differences in the levels of microbiological contamination among butcher shops; samples with counts higher than reference values indicated inefficiency in adopted hygiene procedures. A total of 87 samples were positive for Listeria spp. (60.4%): 22 from tables, 20 from grinders, 16 from knives, 13 from hands, 9 from meat tenderizers, and 7 from butcher shop displays. Thirty-one samples (21.5%) were positive for L. monocytogenes, indicating the presence of the pathogen in meat processing environments. Seventy-four L. monocytogenes isolates were identified, with 52 from serogroups 1/2c or 3c and 22 from serogroups 4b, 4d, 4a, or 4c. All 74 isolates were positive for hlyA, iap, plcA, actA, and internalins (inlA, inlB, inlC, and inlJ). The establishment of appropriate procedures to reduce microbial counts and control the spread of L. monocytogenes in the final steps of the meat production chain is of utmost importance, with obvious effects on the quality and safety of meat products for human consumption.

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Control of Listeria monocytogenes with Combined Antimicrobials on Beef Franks Stored at 4°C

Journal of Food Protection ◽

10.4315/0362-028x-67.10.2296 ◽

2004 ◽

Vol 67 (10) ◽

pp. 2296-2301 ◽

Cited By ~ 39

Author(s):

MILAGROS UHART ◽

SADHANA RAVISHANKAR ◽

NICOLE D. MAKS

Keyword(s):

Listeria Monocytogenes ◽

Safety Issue ◽

Meat Products ◽

Sodium Lactate ◽

Meat Processing ◽

Bacterial Strains ◽

Log Reduction ◽

Sodium Diacetate ◽

Packaged Beef ◽

Antimicrobial Treatments

Contamination of ready-to-eat meat products such as beef franks with Listeria monocytogenes has become a major concern for the meat processing industry and an important food safety issue. The objective of this study was to determine the effectiveness of combinations of antimicrobials as aqueous dipping solutions to control L. monocytogenes on vacuum-packaged beef franks stored at 4°C for 3 weeks. Commercial beef franks were dipped for 5 min in three antimicrobial solutions: pediocin (6,000 AU), 3% sodium diacetate and 6% sodium lactate combined, and a combination of the three antimicrobials. Samples were then inoculated with 107 CFU/g of either four L. monocytogenes strains individually or a cocktail of the four strains, vacuum packaged, and stored at 4°C for 3 weeks. Sampling was carried out at day 0 and after 2 and 3 weeks of storage. Individual strains, as well as the cocktail, exhibited different responses to the antimicrobial treatments. After 2 and 3 weeks of storage at 4°C, pediocin-treated beef franks showed a less than 1-log reduction for all bacterial strains. Samples treated with the sodium diacetate–sodium lactate combination showed about a 1-log reduction after 2 weeks of storage for all strains and between a 1- and 2-log reduction after 3 weeks of storage, depending on the bacterial strain. When the three antimicrobials were combined, reductions ranged between 1 and 1.5 log units and 1.5 to 2.5 log units after 2 and 3 weeks of storage, respectively, at 4°C. These results indicate that the use of combined antimicrobial solutions for dipping treatments is more effective at inhibiting L. monocytogenes than treatments using antimicrobials such as pediocin separately.

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Effect of a Short Cold Storage on Frequency of Spoilage in Pasteurized (Perishable) Canned Meat Products Subjected to the Incubation Test

Journal of Food Protection ◽

10.4315/0362-028x-50.1.56 ◽

1987 ◽

Vol 50 (1) ◽

pp. 56-58

Author(s):

S. KAFEL ◽

E. JOZWIK

Keyword(s):

Cold Storage ◽

Meat Products ◽

Storage Period ◽

Meat Processing ◽

Processing Plants ◽

Canned Meat

Investigations were carried out in 6 meat processing plants in Poland on the effect of a short storage period on the results of the incubation test of various canned pasteurized meat products. From the daily consignments, 1% of the cans was reserved within 1–3 d of production and incubated at 37°C for 3 d. The remaining cans of the consignments were stored at around 8°C. When spoilage resulted in one or more of the incubated cans from any consignment, about 2% of other cans from that consignment were taken, and the incubation test was repeated. These later incubation tests were initiated 7–10 d after the date of production. From among 4,322 cans subjected to first incubation test 980 (22.67%) produced swells but in the repeated incubation carried out on 8,290 cans only 347 (4.18%) became swollen. It is concluded that the bacteria responsible for spoilage of canned pasteurized meat products may disappear or lose their ability to spoil these products during the storage under refrigeration.

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