scholarly journals Characterization and Pathogenic Potential of Listeria monocytogenes Isolates from the Smoked Fish Industry

2001 ◽  
Vol 67 (2) ◽  
pp. 646-653 ◽  
Author(s):  
Dawn M. Norton ◽  
Janet M. Scarlett ◽  
Kelly Horton ◽  
David Sue ◽  
Joanne Thimothe ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Mammalian Cells ◽  
Raw Materials ◽  
Plaque Assay ◽  
Fish Processing ◽  
Pathogenic Potential ◽  
Genetic Lineages ◽  
Smoked Fish ◽  
Fish Industry

ABSTRACT This study was designed to evaluate the hypothesis that some of theListeria monocytogenes subtypes associated with foods, specifically smoked fish, may have an attenuated ability to cause human disease. We tested this hypothesis by using two different approaches: (i) comparison of molecular subtypes found among 117 isolates from smoked fish, raw materials, fish in process, and processing environments with subtypes found among a collection of 275 human clinical isolates and (ii) the evaluation of the cytopathogenicity of industrial isolates. Ribotyping and PCR-restriction fragment length polymorphism typing of the hlyA and actA genes differentiated 23 subtypes among the industrial isolates and allowed classification of the isolates into three genetic lineages. A significantly higher proportion of human isolates (69.1%) than industrial isolates (36.8%) were classified as lineage I, which contains human sporadic isolates and all epidemic isolates. All other industrial isolates (63.2%) were classified as lineage II, which contains only human sporadic isolates. Lineage I ribotypes DUP-1038B and DUP-1042B represented a significantly higher proportion of the human isolates than industrial isolates (5.1%). Lineage II ribotypes DUP-1039C, DUP-1042C, and DUP-1045, shown previously to persist in the smoked fish processing environment, represented nearly 50% of the industrial isolates, compared to 7.6% of the human isolates. Representatives of each subtype were evaluated with a tissue culture plaque assay. Lineage I isolates formed plaques that were significantly larger than those formed by lineage II isolates. Isolates from the smoked fish industry representing three ribotypes formed no plaques or small plaques, indicating that they had an impaired ability to infect mammalian cells. While L. monocytogenes clonal groups linked to human listeriosis cases and outbreaks were isolated, our data also suggest that at least some L. monocytogenes subtypes present in ready-to-eat foods may have limited human-pathogenic potential.

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.

scholarly journals Molecular Studies on the Ecology of Listeria monocytogenes in the Smoked Fish Processing Industry

2001 ◽  
Vol 67 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Dawn M. Norton ◽  
Meghan A. McCamey ◽  
Kenneth L. Gall ◽  
Janet M. Scarlett ◽  
Kathryn J. Boor ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Environmental Samples ◽  
Raw Materials ◽  
Raw Material ◽  
Fish Processing ◽  
Culture Methods ◽  
Smoked Fish ◽  
Molecular Approaches ◽  
Automated Ribotyping

ABSTRACT We have applied molecular approaches, including PCR-based detection strategies and DNA fingerprinting methods, to study the ecology ofListeria monocytogenes in food processing environments. A total of 531 samples, including raw fish, fish during the cold-smoking process, finished product, and environmental samples, were collected from three smoked fish processing facilities during five visits to each facility. A total of 95 (17.9%) of the samples tested positive forL. monocytogenes using a commercial PCR system (BAX for Screening/Listeria monocytogenes), including 57 (27.7%) environmental samples (n = 206), 8 (7.8%) raw material samples (n = 102), 23 (18.1%) samples from fish in various stages of processing(n = 127), and 7 (7.3%) finished product samples (n= 96). L. monocytogenes was isolated from 85 samples (16.0%) using culture methods. Used in conjunction with a 48-h enrichment in Listeria Enrichment Broth, the PCR system had a sensitivity of 91.8% and a specificity of 96.2%. To track the origin and spread of L. monocytogenes, isolates were fingerprinted by automated ribotyping. Fifteen different ribotypes were identified among 85 isolates tested. Ribotyping data established possible contamination patterns, implicating raw materials and the processing environment as potential sources of finished product contamination. Analysis of the distribution of ribotypes revealed that each processing facility had a unique contamination pattern and that specific ribotypes persisted in the environments of two facilities over time (P ≤ 0.0006). We conclude that application of molecular approaches can provide critical information on the ecology of different L. monocytogenes strains in food processing environments. This information can be used to develop practical recommendations for improved control of this important food-borne pathogen in the food industry.

scholarly journals Listeria monocytogenes Isolates from Foods and Humans Form Distinct but Overlapping Populations

2004 ◽  
Vol 70 (10) ◽  
pp. 5833-5841 ◽  
Author(s):  
Michael J. Gray ◽  
Ruth N. Zadoks ◽  
Esther D. Fortes ◽  
Belgin Dogan ◽  
Steven Cai ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Plaque Assay ◽  
Virulence Gene ◽  
The United States ◽  
Polymorphism Analysis ◽  
Genetic Lineages ◽  
The Public ◽  
Cell Spread ◽  
Specific Food

ABSTRACT A total of 502 Listeria monocytogenes isolates from food and 492 from humans were subtyped by EcoRI ribotyping and PCR-restriction fragment length polymorphism analysis of the virulence gene hly. Isolates were further classified into genetic lineages based on subtyping results. Food isolates were obtained through a survey of selected ready-to-eat food products in Maryland and California in 2000 and 2001. Human isolates comprised 42 isolates from invasive listeriosis cases reported in Maryland and California during 2000 and 2001 as well as an additional 450 isolates from cases that had occurred throughout the United States, predominantly from 1997 to 2001. Assignment of isolates to lineages and to the majority of L. monocytogenes subtypes was significantly associated with the isolate source (food or human), although most subtypes and lineages included both human and food isolates. Some subtypes were also significantly associated with isolation from specific food types. Tissue culture plaque assay characterization of the 42 human isolates from Maryland and California and of 91 representative food isolates revealed significantly higher average infectivity and cell-to-cell spread for the human isolates, further supporting the hypothesis that food and human isolates form distinct populations. Combined analysis of subtype and cytopathogenicity data showed that strains classified into specific ribotypes previously linked to multiple human listeriosis outbreaks, as well as those classified into lineage I, are more common among human cases and generate larger plaques than other subtypes, suggesting that these subtypes may represent particularly virulent clonal groups. These data will provide a framework for prediction of the public health risk associated with specific L. monocytogenes subtypes.

Tracking of Listeria monocytogenes in Smoked Fish Processing Plants†

2004 ◽  
Vol 67 (2) ◽  
pp. 328-341 ◽  
Author(s):  
JOANNE THIMOTHE ◽  
KENDRA KERR NIGHTINGALE ◽  
KEN GALL ◽  
VIRGINIA N. SCOTT ◽  
MARTIN WIEDMANN
Keyword(s):  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Control Strategies ◽  
Fish Processing ◽  
Smoked Fish ◽  
Plant Environment ◽  
Fish Samples ◽  
Processing Plants ◽  
Raw Fish ◽  
Contact Surfaces

Four smoked fish processing plants were used as a model system to characterize Listeria monocytogenes contamination patterns in ready-to-eat food production environments. Each of the four plants was sampled monthly for approximately 1 year. At each sampling, four to six raw fish and four to six finished product samples were collected from corresponding lots. In addition, 12 to 14 environmental sponge samples were collected several hours after the start of production at sites selected as being likely contamination sources. A total of 234 raw fish, 233 finished products, and 553 environmental samples were tested. Presumptive Listeria spp. were isolated from 16.7% of the raw fish samples, 9.0% of the finished product samples, and 27.3% of the environmental samples. L. monocytogenes was isolated from 3.8% of the raw fish samples (0 to 10%, depending on the plant), 1.3% of the finished product samples (0 to 3.3%), and 12.8% of the environmental samples (0 to 29.8%). Among the environmental samples, L. monocytogenes was found in 23.7% of the samples taken from drains, 4.8% of the samples taken from food contact surfaces, 10.4% of the samples taken from employee contact surfaces (aprons, hands, and door handles), and 12.3% of the samples taken from other nonfood contact surfaces. Listeria spp. were isolated from environmental samples in each of the four plants, whereas L. monocytogenes was not found in any of the environmental samples from one plant. Overall, the L. monocytogenes prevalence in the plant environment showed a statistically significant (P < 0.0001) positive relationship with the prevalence of this organism in finished product samples. Automated EcoRI ribotyping differentiated 15 ribotypes among the 83 L. monocytogenes isolates. For each of the three plants with L. monocytogenes–positive environmental samples, one or two ribotypes seemed to persist in the plant environment during the study period. In one plant, a specific L. monocytogenes ribotype represented 44% of the L. monocytogenes–positive environmental samples and was also responsible for one of the two finished product positives found in this plant. In another plant, a specific L. monocytogenes ribotype persisted in the raw fish handling area. However, this ribotype was never isolated from the finished product area in this plant, indicating that this operation has achieved effective separation of raw and finished product areas. Molecular subtyping methods can help identify plant-specific L. monocytogenes contamination routes and thus provide the knowledge needed to implement improved L. monocytogenes control strategies.

Implementation of Statistical Tools To Support Identification and Management of Persistent Listeria monocytogenes Contamination in Smoked Fish Processing Plants

2013 ◽  
Vol 76 (5) ◽  
pp. 796-811 ◽  
Author(s):  
THOMAS J. V. MALLEY ◽  
MATTHEW J. STASIEWICZ ◽  
YRJÖ T. GRÖHN ◽  
SHERRY ROOF ◽  
STEVEN WARCHOCKI ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Food Processing ◽  
Adaptive Sampling ◽  
Poisson Model ◽  
Binomial Test ◽  
Sampling Strategies ◽  
Fish Processing ◽  
Smoked Fish ◽  
Processing Plants ◽  
Food Contact Surface

Listeria monocytogenes persistence in food processing plants is a key source of postprocessing contamination of ready-toeat foods. Thus, identification and elimination of sites where L. monocytogenes persists (niches) is critical. Two smoked fish processing plants were used as models to develop and implement environmental sampling plans (i) to identify persistent L. monocytogenes subtypes (EcoRI ribotypes) using two statistical approaches and (ii) to identify and eliminate likely L. monocytogenes niches. The first statistic, a binomial test based on ribotype frequencies, was used to evaluate L. monocytogenes ribotype recurrences relative to reference distributions extracted from a public database; the second statistic, a binomial test based on previous positives, was used to measure ribotype occurrences as a risk factor for subsequent isolation of the same ribotype. Both statistics revealed persistent ribotypes in both plants based on data from the initial 4 months of sampling. The statistic based on ribotype frequencies revealed persistence of particular ribotypes at specific sampling sites. Two adaptive sampling strategies guided plant interventions during the study: sampling multiple times before and during processing and vector swabbing (i.e., sampling of additional sites in different directions [vectors] relative to a given site). Among sites sampled for 12 months, a Poisson model regression revealed borderline significant monthly decreases in L. monocytogenes isolates at both plants (P = 0.026 and 0.076). Our data indicate elimination of an L. monocytogenes niche on a food contact surface; niches on nonfood contact surfaces were not eliminated. Although our data illustrate the challenge of identifying and eliminating L. monocytogenes niches, particularly at nonfood contact sites in small and medium plants, the methods for identification of persistence we describe here should broadly facilitate science-based identification of microbial persistence.

scholarly journals INDUSTRI PENGOLAHAN PERIKANAN DI KABUPATEN KONAWE SELATAN, SULAWESI TENGGARA

2020 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Ernawati Ernawati ◽  
Muhammad Rafiy ◽  
Surianti Surianti
Keyword(s):  
Raw Materials ◽  
Secondary Data ◽  
Raw Material ◽  
Primary Data ◽  
Small Scale ◽  
Local Market ◽  
Market Area ◽  
Fish Processing ◽  
Processing Industry ◽  
Smoked Fish

Penelitian ini bertujuan untuk mengkaji ketersediaan bahan baku dan skala pemasaran industri pengolahan hasil perikanan di Kabupaten Konawe Selatan. Penelitian dilaksanakan pada tahun 2017 dan 2018 dengan menggunakan data primer dan sekunder. Data primer diperoleh melalui kuesioner yang didistribusikan kepada 21 responden pelaku usaha. Data sekunder diperoleh melalui publikasi Badan Pusat Statistik (BPS), Dinas Kelautan dan Perikanan, serta Dinas Perindustrian dan Perdagangan Kabupaten Konawe Selatan. Data diolah melalui analisis deskriptif dan SWOT. Hasil penelitian menunjukkan bahwa kekuatan industri pengolahan hasil perikanan di Kabupaten Konawe Selatan karena bahan baku bersumber dari potensi lokal, namun kelemahannya adalah bahan baku tersebut masih fluktuatif. Kendala bahan baku dialami khususnya oleh industri fermentasi, pengasapan, dan pengeringan ikan. Selain faktor musiman, ketersediaan bahan baku juga terkendala karena bahan baku sebagian besar berasal dari nelayan tradisional dengan struktur armada perikanan yang didominasi oleh nelayan skala kecil. Dengan demikian, pengembangan industri hasil perikanan mensyaratkan perbaikan di sektor hulu melalui sinergitas kebijakan penanganan keterbatasan bahan baku dari berbagai lembaga terkait. Sementara itu, temuan penelitian menunjukkan bahwa 24% unit usaha telah menembus pasar nasional. Ketersediaan bahan baku juga terkendala karena 28% telah menembus pasar regional, sisanya 48% hanya mampu memasarkan produknya di wilayah lokal. Kelompok industri yang hanya menjangkau skala lokal, yaitu industri pelumatan, pengasapan, dan pemindangan, serta beberapa usaha makanan olahan hasil perikanan. Bagi industri yang mengalami jangkauan pasar yang rendah akibat minimnya ketersediaan bahan baku, maka dapat menggunakan bahan baku pengganti namun tetap mempertahankan kualitas produk sesuai dengan selera pasar.Title: Fish Processing Industry in South Konawe Regency,  South East SulawesiThis study aimed to examine the availability of raw materials and the marketing scale of fish processing industry in South Konawe Regency. This research was conducted in 2017 and 2018 using primary and secondary data. Primary data were collected through questionnaires from 21 respondents. Secondary data were collected from Statistics Indonesia, Fisheries and Marine Affairs Office, and Industry and Trade Affairs of South Konawe Regency. Data were analyzed with descriptive analysis and SWOT analysis. The results found that raw material from local sources is the major force of fish processing industry. However, the fluctuating condition of its availability becomes the weakness. Fermentation, smoked fish, and dried fish processing industries suffer from this raw material problems. In addition, the availability of raw materials also largely depends on fishing results from small-scale traditional fishers. Therefore, the development of the fish industries need some specific improvement in the upstream section through the synergy on policies regarding raw material management from related institutions. Meanwhile, the research finding showed that 24% of business units have penetrated national market 28% have penetrated regional market, while the remaining 48% have only penetrated local market. The local industries were pulverized, smoked fish, fish brine, and some other fish processing industries. Those who could only reach small market area due to limited availability of raw materials are able to use substitute materials in a similar quality of market preferences.

scholarly journals Listeria monocytogenes: Knowledge Gained Through DNA Sequence-Based Subtyping, Implications, and Future Considerations

2010 ◽  
Vol 93 (4) ◽  
pp. 1275-1286 ◽  
Author(s):  
Kendra Nightingale
Keyword(s):  
Listeria Monocytogenes ◽  
Dna Sequence ◽  
Foodborne Pathogens ◽  
Sequence Data ◽  
Human Pathogens ◽  
Molecular Subtyping ◽  
Genetic Lineages ◽  
Dna Sequence Data ◽  
Cellular Components

Abstract The purpose of subtyping is to differentiate bacterial isolates beyond the classification of species or subspecies. Subtyping methods can be grouped into two broad categories based on the cellular components targeted: (1) phenotypic subtyping methods that differentiate isolates by the enzymes, proteins, or other metabolites expressed by the cell, and (2) molecular subtyping methods that discriminate isolates based on interrogation of nucleic acid sequences. The two major types of molecular subtyping methods include band-based methods based on fragment pattern data or DNA fingerprints, and methods that generate DNA sequence data. Molecular subtyping methods have shown that Listeria monocytogenes isolates can be classified into four genetic lineages or divisions. Although band-based molecular subtyping methods continue to serve as the gold standard for routine molecular subtyping of most clinically important foodborne pathogens, including L. monocytogenes, the explosion of recently completed and ongoing DNA sequencing projects, and thus available DNA sequence data, have stimulated efforts to develop highly discriminatory and high-throughput DNA sequence-based subtyping methods for L. monocytogenes. L. monocytogenes represents one of the most highly sequenced human pathogens; more than 20 genome sequences are currently available for this organism. This review provides an overview of the concepts behind subtyping and discusses the application of molecular subtyping methods, with an emphasis on DNA sequence-based subtyping methods to characterize L. monocytogenes.

scholarly journals MUTU SENSORIK DAN NILAI–K IKAN CAKALANG (Katsuwonus pelamis. L) DARI INDUSTRI PENGOLAHAN IKAN ASAP DI MANADO

2012 ◽  
Vol 8 (3) ◽  
pp. 103
Author(s):  
Hens Onibala
Keyword(s):  
Raw Materials ◽  
Skipjack Tuna ◽  
Class Iii ◽  
Fish Processing ◽  
Katsuwonus Pelamis ◽  
Processing Industry ◽  
K Value ◽  
Organoleptic Quality ◽  
Smoked Fish ◽  
North Sulawesi

Penelitian ini bertujuan untuk mengetahui kajian mutu sensorik dan tingkat kesegaran awal dari ikan cakalang (Katsuwonus pelamis. L) yang digunakan sebagai bahan baku dalam pengolahan ikan asap di Manado. Ikan cakalang yang digunakan sebagai bahan baku memiliki nilai organoleptik rata–rata 7,79 dan nilai–K 37,08%. Hal ini berarti bahwa bahan baku ikan cakalang yang digunakan pada industri pe­ngolahan ikan asap tersebut pada umumnya menggunakan bahan baku ikan yang masuk dalam tingkatan mutu III. Kata kunci: cakalang, Katsuwonus pelamis. L, ikan asap, nilai–K, organoleptik.This objective of this research is to identifying the initial organoleptic quality and freshness level of skipjack tuna, Katsuwonus pelamis. L, used as raw materials for smoked fish in Manado, North Sulawesi. Results found that skipjack tuna used as raw materials for smoked fish has an average organoleptic value of 7.79 and K-value of 37.08%. It means that the raw materials of the skipjack used in the smoked fish processing industry come from the fish of class III quality. Keywords: skipjack tuna, Katsuwonus pelamis. L, smoked fish, K-value, organoleptic.

Note. Occurrence of Listeria spp. in salmon-trout (Onchorhyncus mykiss) and salmon (Salmo salar) / Nota. Presencia de Listeria spp. en trucha asalmonada (Onchorhyncus mykiss) y salmón (Salmo salar)

1998 ◽  
Vol 4 (2) ◽  
pp. 121-125 ◽  
Author(s):  
M. Vaz-Velho ◽  
G. Duarte ◽  
P. Gibbs
Keyword(s):  
Salmo Salar ◽  
Environmental Samples ◽  
Raw Materials ◽  
Raw Material ◽  
Smoked Fish ◽  
The North ◽  
Smoked Salmon ◽  
Trout Farms ◽  
Fish Industry ◽  
Sources Of Contamination

Salmon-trout ( Onchorhyncus mykiss) and salmon ( Salmo salar) are the main raw materials in the cold-smoked fish industry. It is important to prevent the contamination of these ready-to-eat products with Listeria monocytogenes and other ( Listeria spp.) because the temperature used in the cold-smoking process is not sufficient to inactivate these organisms. The presence of Listeria spp. and L. monocytogenes in the cold-smoked salmon and salmon-trout processing chains of three Portuguese factories examined was already confirmed in previous studies. Thus, it was important to ascertain the possible sources of contamination, the raw material being the most important one. All the Portuguese cold-smoking fish factories use fresh salmon-trout from two trout farms in the north of Portugal and Norwegian salmon which arrives by lorry every week under refrigeration, imported always by the same company; 88 samples of salmon and salmon-trout were analysed; 67 environmental samples from the two trout farms were also examined. The overall frequency ( n = 40) of Listeria spp. and L. monocytogenes in salmon was 12 and 0% respectively. The overall frequency (n = 48) of Listeria spp. and L. monocytogenes in salmon-trout was 6.3 and 2.1% respec tively. Listeria was not found in the environmental samples.

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