Contamination Patterns of Listeria monocytogenes in Cold-Smoked Pork Processing

2010 ◽  
Vol 73 (11) ◽  
pp. 2103-2109 ◽  
Author(s):  
AIVARS BĒRZIŅŠ ◽  
SANNA HELLSTRÖM ◽  
INDULIS SILIŅŠ ◽  
HANNU KORKEALA
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Meat Products ◽  
Pulsed Field Gel Electrophoresis ◽  
Processing Plant ◽  
Environmental Sampling ◽  
Meat Processing ◽  
Pork Products ◽  
Plant Environment ◽  
Pork Samples

Contamination patterns of Listeria monocytogenes were studied in a cold-smoked pork processing plant to identify the sources and possible reasons for the contamination. Environmental sampling combined with pulsed-field gel electrophoresis (PFGE) subtyping and serotyping were applied to investigate the genetic diversity of L. monocytogenes in the plant environment and ready-to-eat (RTE) cold-smoked pork products. A total of 183 samples were collected for contamination analyses, including samples of the product at different stages during manufacture (n = 136) and environmental samples (n = 47) in 2009. L. monocytogenes isolates, previously recovered from 73 RTE cold-smoked pork samples and collected from the same meat processing plant in 2004, were included in this study. The brining machine and personnel working with brining procedures were the most contaminated places with L. monocytogenes. The overall prevalence of L. monocytogenes in raw pork (18%) increased to 60% after the brining injections. The brining machine harbored six different PFGE types belonging to serotypes 1/2a, 1/2c, 4b, and 4d, which were found on the feeding teeth, smooth surfaces, and spaces of the machine, thus potentially facilitating dissemination of L. monocytogenes contamination. Two PFGE types (2 and 8) belonging to serotypes 1/2a and 1/2c were recovered from RTE cold-smoked pork collected in 2004, and from surfaces of the brining machine sampled in 2009, and may indicate the presence of persistent L. monocytogenes strains in the plant. Due to poor hygiene design, removal of the brining machine from the production of cold-smoked meat products should be considered to reduce L. monocytogenes contamination in the finished products.

Prevalence and Genetic Diversity of Listeria monocytogenes in Vacuum-Packaged Ready-to-Eat Meat Products at Retail Markets in Latvia

2009 ◽  
Vol 72 (6) ◽  
pp. 1283-1287 ◽  
Author(s):  
AIVARS BĒRZIŅŠ ◽  
MARGARITA TERENTJEVA ◽  
HANNU KORKEALA
Keyword(s):  
Listeria Monocytogenes ◽  
Shelf Life ◽  
Meat Products ◽  
Processing Plant ◽  
Meat Processing ◽  
Pork Products ◽  
Beef Products ◽  
Processing Plants ◽  
Serotype 1 ◽  
Packaged Beef

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.

Molecular Ecology of Listeria monocytogenes and Other Listeria Species in Small and Very Small Ready-to-Eat Meat Processing Plants

2011 ◽  
Vol 74 (1) ◽  
pp. 63-77 ◽  
Author(s):  
SHANNA K. WILLIAMS ◽  
SHERRY ROOF ◽  
ELIZABETH A. BOYLE ◽  
DENNIS BURSON ◽  
HARSHAVARDHAN THIPPAREDDI ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Environmental Samples ◽  
Molecular Ecology ◽  
Meat Products ◽  
Positive Sample ◽  
Pulsed Field Gel Electrophoresis ◽  
Meat Processing ◽  
Molecular Serotyping ◽  
Processing Plants ◽  
Allelic Type

A longitudinal study was conducted to track Listeria contamination patterns in ready-to-eat meats from six small or very small meat processing plants located in three states over 1 year. A total of 688 environmental sponge samples were collected from nonfood contact surfaces during bimonthly visits to each plant. Overall, L. monocytogenes was isolated from 42 (6.1%) environmental samples, and its prevalence ranged from 1.7 to 10.8% across different plants. Listeria spp., other than L. monocytogenes, were isolated from 9.5% of samples overall, with the prevalence ranging from 1.5 to 18.3% across different plants. The prevalence of L. monocytogenes correlated well with that of other Listeria spp. for some but not all plants. One L. monocytogenes isolate representing each positive sample was characterized by molecular serotyping, EcoRI ribotyping, and pulsed-field gel electrophoresis typing. Seven sample sites tested positive for L. monocytogenes on more than one occasion, and the same ribotype was detected more than once at five of these sites. Partial sigB sequencing was used to speciate other Listeria spp. isolates and assign an allelic type to each isolate. Other Listeria spp. were isolated more than once from 14 sample sites, and the same sigB allelic type was recovered at least twice from seven of these sites. One plant was colonized by an atypical hemolytic L. innocua strain. Our findings indicate that small and very small meat processing plants that produce ready-to-eat meat products are characterized by a varied prevalence of Listeria, inconsistent correlation between contamination by L. monocytogenes and other Listeria spp., and a unique Listeria molecular ecology.

Analysis of Listeria monocytogenes Strain Distribution in a Pork Slaughter and Cutting Plant in the Province of Quebec

2014 ◽  
Vol 77 (12) ◽  
pp. 2121-2128 ◽  
Author(s):  
GUILLAUME LARIVIÉRE-GAUTHIER ◽  
ANN LETELLIER ◽  
ANNAËLLE KÉROUANTON ◽  
SADJIA BEKAL ◽  
SYLVAIN QUESSY ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Food Production ◽  
Control Strategies ◽  
Meat Products ◽  
Pulsed Field Gel Electrophoresis ◽  
Public Health Perspective ◽  
Pulsed Field ◽  
Plant Environment ◽  
Production Stages

Following the 2008 Canadian listeriosis outbreak associated with ready-to-eat (RTE) meat products, regulations on the presence of Listeria monocytogenes in RTE food production facilities were modified by Health Canada, confirming the need to control this pathogen, not only in the final product but also in the plant environment. Information on the occurrence of this microorganism during the early steps of production, such as the slaughtering process and in the cutting area, is scarce in Canada. In this study, we sampled different production steps in a slaughtering and cutting plant in the province of Quebec over a 2-year period. The lairage pens, representative areas of the slaughter line, and cutting zones were targeted after their respective cleaning procedures. A total of 874 samples were analyzed for the presence of L. monocytogenes. Characterization was done by first genoserogrouping the isolates using multiplex PCR and then using a pulsed-field gel electrophoresis approach. L. monocytogenes was detected throughout all production stages. The 108 positive samples found were analyzed further, and we established that there were 4 different serogroups, with serogroup IIb being the most prevalent. The results of pulsed-field gel electrophoresis analysis showed a significant decrease in the diversity of strains from the first areas of the plant to the cutting room (10 pulsotypes in 13 positive samples in lairage and 9 in 86 positive samples in cutting) and also showed the overrepresentation of a single predominant strain in the cutting room environment (type 1, representing 96.1% of the isolates). Biofilm formation analysis of the strains cannot exclusively explain the transitions we observed. A strong genotypic similarity between strains isolated in the early production areas and some strains in the cutting room was shown. These results support the need for better surveillance of L. monocytogenes prior to RTE food production in order to design control strategies that are better adapted from a public health perspective.

Monitoring Hygiene On- and At-Line Is Critical for Controlling Listeria monocytogenes during Produce Processing

2008 ◽  
Vol 71 (4) ◽  
pp. 735-741 ◽  
Author(s):  
KRYSTYNA PAPPELBAUM ◽  
KATHARINA GRIF ◽  
INGRID HELLER ◽  
REINHARD WÜRZNER ◽  
INGEBORG HEIN ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Control Point ◽  
Daily Basis ◽  
Pulsed Field Gel Electrophoresis ◽  
Contamination Level ◽  
Processing Plant ◽  
Pulsed Field ◽  
Critical Control Point ◽  
Plant Environment

The prevalence of Listeria monocytogenes in different types of produce and on processing plant environments was investigated over a 4-year period in a large produce processing plant in Poland. Prevalence of L. monocytogenes was 46% in frozen vegetables and 41.3% in swab samples taken from the plant environment. Survival studies using artificial inocula demonstrated that the number of Listeria in frozen produce stored for 100 days did not significantly decrease in relation to the initial contamination level. A subset of 129 L. monocytogenes isolates originating from produce and the plant environment were typed by pulsed-field gel electrophoresis. Seventy-six of these isolates were retyped by ribo- and serotyping. Thirteen pulsotypes and 18 ribotypes were distinguished. Persistent Listeria isolates were found even when cleansing and sanitization was applied on a daily basis. Nine (69.2%) of 13 pulsotypes were recovered during a period of more than 2 years. L. monocytogenes of the same pulsotype was isolated from broccoli sampled directly before and after blanching, thus suggesting that blanching at 92 to 95°C for 4 to 8 min did not result in a Listeria-free product, most likely due to massive recontamination. This finding is of importance since blanching is the only critical control point in produce processing. Cross-contamination between the two lines was demonstrated through isolating L. monocytogenes strains indistinguishable by pulsed-field gel electrophoresis from contaminated gloves and floor surfaces.

scholarly journals Genetic Listeria monocytogenes Types in the Pork Processing Plant Environment: From Occasional Introduction to Plausible Persistence in Harborage Sites

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 717
Author(s):  
Niels Demaître ◽  
Geertrui Rasschaert ◽  
Lieven De Zutter ◽  
Annemie Geeraerd ◽  
Koen De Reu
Keyword(s):  
Genetic Diversity ◽  
Environmental Samples ◽  
Genetic Characterization ◽  
Processing Plant ◽  
Pfge Analysis ◽  
Food Contact ◽  
Plant Environment ◽  
Food Contact Surfaces ◽  
Contact Surfaces ◽  
Cleaning And Disinfection

The purpose of this study was to investigate the L. monocytogenes occurrence and genetic diversity in three Belgian pork cutting plants. We specifically aim to identify harborage sites and niche locations where this pathogen might occur. A total of 868 samples were taken from a large diversity of food and non-food contact surfaces after cleaning and disinfection (C&D) and during processing. A total of 13% (110/868) of environmental samples tested positive for L. monocytogenes. When looking in more detail, zone 3 non-food contact surfaces were contaminated more often (26%; 72/278) at typical harborage sites, such as floors, drains, and cleaning materials. Food contact surfaces (zone 1) were less frequently contaminated (6%; 25/436), also after C&D. PFGE analysis exhibited low genetic heterogeneity, revealing 11 assigned clonal complexes (CC), four of which (CC8, CC9, CC31, and CC121) were predominant and widespread. Our data suggest (i) the occasional introduction and repeated contamination and/or (ii) the establishment of some persistent meat-adapted clones in all cutting plants. Further, we highlight the importance of well-designed extensive sampling programs combined with genetic characterization to help these facilities take corrective actions to prevent transfer of this pathogen from the environment to the meat.

scholarly journals Identification and Characterization of Pathogenic Yersinia enterocolitica Isolates by PCR and Pulsed-Field Gel Electrophoresis

2005 ◽  
Vol 71 (7) ◽  
pp. 3674-3681 ◽  
Author(s):  
S. Thisted Lambertz ◽  
M.-L. Danielsson-Tham
Keyword(s):  
Multiplex Pcr ◽  
Yersinia Enterocolitica ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Virulence Plasmid ◽  
Pork Meat ◽  
Pulsed Field ◽  
Pork Products ◽  
Food Borne ◽  
Pork Samples

ABSTRACT Approximately 550 to 600 yersiniosis patients are reported annually in Sweden. Although pigs are thought to be the main reservoir of food-borne pathogenic Yersinia enterocolitica, the role of pork meat as a vehicle for transmission to humans is still unclear. Pork meat collected from refrigerators and local shops frequented by yersiniosis patients (n = 48) were examined for the presence of pathogenic Yersinia spp. A combined culture and PCR method was used for detection, and a multiplex PCR was developed and evaluated as a tool for efficient identification of pathogenic food and patient isolates. The results obtained with the multiplex PCR were compared to phenotypic test results and confirmed by pulsed-field gel electrophoresis (PFGE). In all, 118 pork products (91 raw and 27 ready-to-eat) were collected. Pathogenic Yersinia spp. were detected by PCR in 10% (9 of 91) of the raw pork samples (loin of pork, fillet of pork, pork chop, ham, and minced meat) but in none of the ready-to-eat products. Isolates of Y. enterocolitica bioserotype 4/O:3 were recovered from six of the PCR-positive raw pork samples; all harbored the virulence plasmid. All isolates were recovered from food collected in shops and, thus, none were from the patients' home. When subjected to PFGE, the six isolates displayed four different NotI profiles. The same four NotI profiles were also present among isolates recovered from the yersiniosis patients. The application of a multiplex PCR was shown to be an efficient tool for identification of pathogenic Y. enterocolitica isolates in naturally contaminated raw pork.

scholarly journals Occurrence of Listeria monocytogenes in Ready-to-Eat Meat Products and Meat Processing Plants in Spain

Foods ◽  
2015 ◽  
Vol 4 (4) ◽  
pp. 271-282 ◽  
Author(s):  
Diego Gómez ◽  
Laura Iguácel ◽  
Mª Rota ◽  
Juan Carramiñana ◽  
Agustín Ariño ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Meat Products ◽  
Meat Processing ◽  
Processing Plants

scholarly journals Sources of Listeria monocytogenes Contamination in a Cold-Smoked Rainbow Trout Processing Plant Detected by Pulsed-Field Gel Electrophoresis Typing

1999 ◽  
Vol 65 (1) ◽  
pp. 150-155 ◽  
Author(s):  
Tiina Autio ◽  
Sebastian Hielm ◽  
Maria Miettinen ◽  
Anna-Maija Sjöberg ◽  
Kaarina Aarnisalo ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Hot Water ◽  
Processing Plant ◽  
Pulsed Field ◽  
Eradication Program ◽  
Fish Samples ◽  
Raw Fish

ABSTRACT Sites of Listeria monocytogenes contamination in a cold-smoked rainbow trout (Oncorhynchus mykiss) processing plant were detected by sampling the production line, environment, and fish at different production stages. Two lots were monitored. The frequency of raw fish samples containing L. monocytogenes was low. During processing, the frequency of fish contaminated with L. monocytogenes clearly rose after brining, and the most contaminated sites of the processing plant were the brining and postbrining areas. A total of 303 isolates from the raw fish, product, and the environment were characterized by pulsed-field gel electrophoresis (PFGE). PFGE yielded nine pulsotypes, which formed four clusters. The predominating L. monocytogenespulsotypes of the final product were associated with brining and slicing, whereas contaminants of raw fish were not detected in the final product. Air-mediated contamination in the plant could not be proved. In accordance with these results, an L. monocytogenes eradication program was planned. The use of hot steam, hot air, and hot water seemed to be useful in eliminatingL. monocytogenes. None of the control samples taken in the 5 months after the eradication program was implemented containedL. monocytogenes.

Listeria monocytogenes Contamination Patterns for the Smoked Fish Processing Environment and for Raw Fish

2003 ◽  
Vol 66 (1) ◽  
pp. 52-60 ◽  
Author(s):  
ADAM D. HOFFMAN ◽  
KENNETH L. GALL ◽  
DAWN M. NORTON ◽  
MARTIN WIEDMANN
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Contamination ◽  
West Coast ◽  
Environmental Samples ◽  
Raw Materials ◽  
Processing Plant ◽  
Fish Processing ◽  
Smoked Fish ◽  
Fish Samples ◽  
Raw Fish

Reliable data on the sources of Listeria monocytogenes contamination in cold-smoked fish processing are crucial in designing effective intervention strategies. Environmental samples (n = 512) and raw fish samples (n = 315) from two smoked fish processing facilities were screened for L. monocytogenes, and all isolates were subtyped by automated ribotyping to examine the relationship between L. monocytogenes contamination from raw materials and that from environmental sites. Samples were collected over two 8-week periods in early spring and summer. The five types of raw fish tested included lake whitefish, sablefish, farm-raised Norwegian salmon, farm-raised Chilean salmon, and feral (wild-caught) salmon from the U.S. West Coast. One hundred fifteen environmental samples and 46 raw fish samples tested positive for L. monocytogenes. Prevalence values for environmental samples varied significantly (P < 0.0001) between the two plants; plant A had a prevalence value of 43.8% (112 of 256 samples), and plant B had a value of 1.2% (3 of 256 samples). For plant A, 62.5% of drain samples tested positive for L. monocytogenes, compared with 32.3% of samples collected from other environmental sites and 3.1% of samples collected from food contact surfaces. Ribotyping identified 11 subtypes present in the plant environments. Multiple subtypes, including four subtypes not found on any raw fish, were found to persist in plant A throughout the study. Contamination prevalence values for raw fish varied from 3.6% (sablefish) to 29.5% (U.S. West Coast salmon), with an average overall prevalence of 14.6%. Sixteen separate L. monocytogenes subtypes were present on raw fish, including nine that were not found in the plant environment. Our results indicate a disparity between the subtypes found on raw fish and those found in the processing environment. We thus conclude that environmental contamination is largely separate from that of incoming raw materials and includes strains persisting, possibly for years, within the plant. Operational and sanitation procedures appear to have a significant impact on environmental contamination, with both plants having similar prevalence values for raw materials but disparate contamination prevalence values for the environmental sites. We also conclude that regular L. monocytogenes testing of drains, combined with molecular subtyping of the isolates obtained, allows for efficient monitoring of persistent L. monocytogenes contamination in a processing plant.

Traceback Identification of an Ingredient (Pork Dewlap) as the Possible Source of Listeria monocytogenes Serotype 4b Contamination in Raw Chicken Products

2007 ◽  
Vol 70 (6) ◽  
pp. 1513-1517 ◽  
Author(s):  
VICTORIA LÓPEZ ◽  
SAGRARIO ORTIZ ◽  
ALFREDO CORUJO ◽  
PILAR LÓPEZ ◽  
JAIME NAVAS ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Restriction Analysis ◽  
Virulence Gene ◽  
Pulsed Field Gel Electrophoresis ◽  
Processing Plant ◽  
Poultry Processing ◽  
Serotype 4B ◽  
Fresh Products ◽  
Allelic Analysis

In surveys conducted on finished product samples from a single poultry processing plant in Spain, Listeria monocytogenes was found in 14 different uncooked products. To track contamination patterns, 77 L. monocytogenes isolates were characterized by PCR-based serotyping, pulsed-field gel electrophoresis (PFGE) restriction analysis, and PCR-based allelic analysis of the virulence gene actA. Serotyping revealed that 12 isolates (15.6%) were of the L. monocytogenes serotype 4b complex (serotype 4b or the closely related serotypes 4d and 4e). A combination of endonucleases AscI and ApaI PFGE patterns yielded 15 different pulsotypes among all 77 tested isolates. All the serotype 4b isolates belonged to one pulsotype. Sequencing of the actA gene confirmed that all serotype 4b isolates corresponded to the same allelic subtype. The subtype was recovered from five product types, but its presence was not correlated with the production line or the date of isolation, suggesting a possible association of this strain with a common ingredient. This traceback investigation established that pork dewlap, an ingredient common to all the products contaminated with this strain, was the most probable source of L. monocytogenes 4b. The same 4b strain was isolated from four samples of pork dewlap from one specific supplier. After replacement of this contaminated ingredient in the fresh products, this strain of L. monocytogenes serotype 4b was not detected. This study confirms the effectiveness of molecular subtyping to control contamination by specific strains of L. monocytogenes and the importance of testing the different ingredients added to the food products.

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