Listeria monocytogenes in Smoked Salmon and Other Smoked Fish at Retail in Italy: Frequency of Contamination and Strain Characterization in Products from Different Manufacturers

2017 ◽  
Vol 80 (2) ◽  
pp. 271-278 ◽  
Author(s):  
Vicdalia Aniela Acciari ◽  
Marina Torresi ◽  
Luigi Iannetti ◽  
Silvia Scattolini ◽  
Francesco Pomilio ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Confidence Interval ◽  
Maximum Level ◽  
Restriction Enzymes ◽  
Pulsed Field Gel Electrophoresis ◽  
Strain Characterization ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Italian Market ◽  
Different Levels

ABSTRACT Seven hundred seventy-eight samples of packaged smoked fish (774 smoked salmon and 4 smoked swordfish) on sale in Italy, from 50 different manufacturers located in 12 European Union countries, were purchased from the Italian market between May and December 2011. The surface temperatures of the samples on sale ranged from 0 to 13°C (3.4 ± 1.5°C, mean ± SD). Six hundred eighty (87.4%) of 778 samples were stored at ≤4°C. One hundred fifty-seven samples (20.2%, 95% confidence interval 17.5 to 23.1%) were contaminated by Listeria monocytogenes, with 26 samples (3.3%, 95% confidence interval 2.3 to 4.8%) at levels >100 CFU/g. The maximum level of contamination was 1.3 ×106 CFU/g. The differences in the level of contamination of smoked fish between countries (χ2 = 91.54, P < 0.05) and manufacturers (χ2 = 193.22, P < 0.05) were significant. The frequency of detection for products from different manufacturing premises ranged from 0 to 76.9%. Serotyping by serological agglutination revealed that the main serotypes detected were 1/2a (65.3%) and 1/2b (22.4%). Pulsed-field gel electrophoresis typing with restriction enzymes AscI and ApaI yielded 36 pulsotypes from 144 isolates, clustering into 17 groups. Eight main pulsotypes accounted for 70.8% of the isolates. Three of the main pulsotypes were exclusively from products of a single manufacturer. In general, products from the same manufacturer showed genetic homogeneity, with one strongly prevalent pulsotype. Different manufacturers usually showed very different levels of contamination of the final product, confirming the importance of the management of process hygiene for controlling L. monocytogenes contamination.

Inactivation of Listeria monocytogenes on Hot-smoked Salmon by the Interaction of Heat and Smoke or Liquid Smoke†

1997 ◽  
Vol 60 (6) ◽  
pp. 649-654 ◽  
Author(s):  
FRANK T. POYSKY ◽  
ROHINEE N. PARANJPYE ◽  
MARK E. PETERSON ◽  
GRETCHEN A. PELROY ◽  
ANNE E. GUTTMAN ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Minimum Temperature ◽  
Soluble Fraction ◽  
Internal Temperature ◽  
Lethal Temperature ◽  
Entire Process ◽  
Smoked Fish ◽  
Liquid Smoke ◽  
Full Strength ◽  
Smoked Salmon

L. monocytogenes was inoculated onto the surface of brined salmon steaks and heat processed in a commercial smokehouse to simulate a hot process for preparing smoked fish. The minimum temperature required for inactivation of L. monocytogenes was 153°F (67.2°C) when generated smoke was applied throughout the entire process. When generated smoke was added only during the last half of the process, L. monocytogenes was recovered from steaks heated to temperatures as high as 176°F (80.0°C). When smoke was not applied during the process, L. monocytogenes survived on steaks heated to internal temperatures between 131°F and 181°F (55.0 to 82.8°C) but was not isolated from steaks heated above 181°F (82.8°C). When liquid smoke CharSol C-l0 was applied as a full-strength (100%) dip before processing, L. monocytogenes was inactivated in samples processed at temperatures as low as 138°F (58.9°C). When liquid smoke l0-Poly or CharSol C-l0 was applied at a concentration of 50%, the lethal temperature was increased to the range of 145 to 150°F (62.8 to 65.6°C). With further dilution of C-l0 to 25% and 10% the inactivation temperatures increased to 156°F (68.9°C) and 163°F (72.8°C). A full-strength dip of CharOil, the oil-soluble fraction of CharSol C-l0, was less effective, and L. monocytogenes survived in salmon steaks processed to an internal temperature of 166°F (74.4°C), the highest temperature tested with this liquid smoke. This study provides evidence that heat alone is not reliable for inactivation of L. monocytogenes during the hot-smoking process. The proper stage and duration of smoke application or proper composition and concentration of liquid smoke in combination with heat are critical for inactivation of the organism.

Antilisterial Activity of a Carnobacterium piscicola Isolated from Brazilian Smoked Fish (Surubim [Pseudoplatystoma sp.]) and Its Activity against a Persistent Strain of Listeria monocytogenes Isolated from Surubim

2005 ◽  
Vol 68 (10) ◽  
pp. 2068-2077 ◽  
Author(s):  
VIRGÍNIA F. ALVES ◽  
ELAINE C. P. DE MARTINIS ◽  
MARIA TERESA DESTRO ◽  
BIRTE FONNESBECH VOGEL ◽  
LONE GRAM
Keyword(s):  
Listeria Monocytogenes ◽  
Freshwater Fish ◽  
Random Amplified Polymorphic Dna ◽  
Model Systems ◽  
Fish Products ◽  
Tropical Regions ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Carnobacterium Piscicola

Data on the prevalence and growth of Listeria monocytogenes in lightly preserved fish products from subtropical and tropical regions are very scarce. Our research describes L. monocytogenes that was detected in 5% of the packages of cold-smoked surubim, a native Brazilian freshwater fish that we analyzed, and shows that the strains isolated were of the same random amplified polymorphic DNA subtype as the strains that were isolated from the same factory 4 years earlier. A bacteriocinogenic strain of Carnobacterium piscicola (strain C2), isolated from vacuum-packed cold-smoked surubim, and two C. piscicola strains, isolated from vacuum-packed, cold-smoked salmon, were capable of limiting or completely inhibiting the growth of an L. monocytogenes (strain V2) isolated from surubim in fish peptone model systems incubated at 10°C. Mono-cultures of L. monocytogenes reached 108 CFU/ml (g), whereas the growth of L. monocytogenes was completely inhibited by C. piscicola C2. The bacteriocinogenic C. piscicola A9b+ and its nonbacteriocinogenic mutant A9b− reduced maximum Listeria levels by 2 to 3 log units. Both bacteriocinogenic C. piscicola strains prevented listerial growth in cold-smoked fish juices (surubim and salmon). Although the carnobacteria grew poorly on cold-smoked surubim at 10°C, the strains were able to reduce maximum Listeria counts by 1 to 3 log units in an artificially inoculated product (surubim). We conclude that Brazilian smoked fish products harbor L. monocytogenes and should be stabilized against the growth of the organism. C. piscicola C2 has the potential for use as a bioprotective culture in surubim and other lightly preserved fish, but further studies are required to optimize its effect.

Comparison of Selective Direct Plating Media for Enumeration and Recovery of L. monocytogenes from Cold-process (smoked) Fish

1992 ◽  
Vol 55 (11) ◽  
pp. 905-909 ◽  
Author(s):  
ROHINEE N. PARANJPYE ◽  
GRETCHEN A. PELROY ◽  
MARK E. PETERSON ◽  
FRANK T. POYSKY ◽  
PAUL J. HOLLAND ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Lithium Chloride ◽  
Indicator System ◽  
Water Phase ◽  
Direct Plating ◽  
Selective Media ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Selective Agar ◽  
Added Salt

Three selective media were evaluated for direct plating recovery and enumeration of Listeria monocytogenes in the presence of high levels of a variety of microorganisms occurring on cold-process (smoked) salmon products. Sliced salmon was brined to contain either no added salt, 3, or 5% water-phase NaCl, or 3 or 5% NaCl plus 140 ppm NaNO2. The slices were packaged in oxygen-permeable film or sealed under vacuum in oxygen-impermeable film, and stored at 10°C or 5°C until total microbial loads reached 106 to 109 CFU/g. Oxford formulation of Listeria selective agar and Lee's modification of Listeria selective agar achieved quantitative recovery of 102 cells per ml of L. monocytogenes strain Scott A in the presence of diluted slurries of these fish containing 104 to 108 CFU/ml of background organisms. A modification of lithium chloride-phenylethanol-moxalactam agar containing an iron-esculin indicator system sometimes failed because of interfering growth by the background microflora.

Human isolates ofListeria monocytogenesin Sweden during half a century (1958–2010)

2014 ◽  
Vol 142 (11) ◽  
pp. 2251-2260 ◽  
Author(s):  
G. LOPEZ-VALLADARES ◽  
W. THAM ◽  
V. SINGH PARIHAR ◽  
S. HELMERSSON ◽  
B. ANDERSSON ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Pfge Type ◽  
Pulsed Field ◽  
Smoked Salmon ◽  
Soft Cheese ◽  
Cheese Production

SUMMARYIsolates ofListeria monocytogenes(n = 932) isolated in Sweden during 1958–2010 from human patients with invasive listeriosis were characterized by serotyping and pulsed-field gel electrophoresis (PFGE) (AscI). Of the 932 isolates, 183 different PFGE types were identified, of which 83 were each represented by only one isolate. In all, 483 serovar 1/2a isolates were distributed over 114 PFGE types; 90 serovar 1/2b isolates gave 32 PFGE types; 21 serovar 1/2c isolates gave nine PFGE types; three serovar 3b isolates gave one PFGE type; and, 335 serovar 4b isolates gave 31 PFGE types. During the 1980s in Sweden, several serovar 4b cases were associated with the consumption of European raw soft cheese. However, as cheese-production hygiene has improved, the number of 4b cases has decreased. Since 1996, serovar 1/2a has been the dominantL. monocytogenesserovar in human listeriosis in Sweden. Therefore, based on current serovars and PFGE types, an association between human cases of listeriosis and the consumption of vacuum-packed gravad and cold-smoked salmon is suggested.

Examination of Listeria monocytogenes in Seafood Processing Facilities and Smoked Salmon in the Republic of Ireland

2015 ◽  
Vol 78 (12) ◽  
pp. 2184-2190 ◽  
Author(s):  
DARA LEONG ◽  
AVELINO ALVAREZ-ORDÓÑEZ ◽  
SARAH ZAOUALI ◽  
KIERAN JORDAN
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Benzalkonium Chloride ◽  
Food Samples ◽  
Pulsed Field Gel Electrophoresis ◽  
Pulsed Field ◽  
Republic Of Ireland ◽  
Smoked Salmon ◽  
The Republic ◽  
Seafood Processing

Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a relatively rare but life-threatening disease primarily affecting immunocompromised individuals. The aim of this study was to determine the prevalence of L. monocytogenes in the seafood processing industry in the Republic of Ireland. The occurrence of L. monocytogenes was determined by regular sampling of both food samples and processing environment swabs at eight seafood processing facilities over two calendar years. All samples were analyzed by the International Organization for Standardization 11290-1 standard method, and the isolates were characterized by PCR, pulsed-field gel electrophoresis, serotyping, and the occurrence of some genes related to survival under stress (SSI-1, Tn6188, and bcrABC). A prevalence of 2.5% in 508 samples (433 environmental swabs and 75 food samples) was found. From the isolates obtained, eight different pulsed-field gel electrophoresis profiles were identified, two occurring in more than one facility and one occurring in food and the environment. Five of the eight pulsotypes identified contained at least one of the three stress survival–related genes tested. The tolerance of the isolates to benzalkonium chloride, a representative quaternary ammonium compound, was also examined and ranged from 5.5 ± 0.5 to 8.5 ± 0.5 ppm of benzalkonium chloride. To evaluate the ability of smoked salmon to support the growth of L. monocytogenes, including the T4 widespread pulsotype that was isolated, a challenge test was performed on cold-smoked salmon obtained from two separate producers. The results showed clearly that both types of smoked salmon supported the growth of L. monocytogenes. Although occurrence of L. monocytogenes on seafood was low, this study showed that the smoked salmon used in this study can support the growth of L. monocytogenes; therefore, vigilance is required in the processing facilities to reduce the associated risk.

scholarly journals Identification and serotyping of Listeria monocytogenes, isolated from various salmon products, sold in retail market in Lithuania

2021 ◽  
Vol 10 (3) ◽  
Author(s):  
Ineta Simonavičienė ◽  
Gintarė Zakariene ◽  
Aušra Lozoraitytė ◽  
Gintarė Zaborskienė ◽  
Gediminas Gerulis ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Multiplex Pcr ◽  
Local Market ◽  
Microbiological Analysis ◽  
Retail Market ◽  
Fish Products ◽  
Smoked Fish ◽  
Smoked Salmon ◽  
Study Results ◽  
Fish Product

Cold smoked salmon products (belly flaps, pieces, fillet, and loin) obtained from the retail market in Lithuania were tested for the presence of L. monocytogenes. It was found that contamination of the cold smoked fish products with Listeria spp. depends on the type of the product. Contamination with listeria in salmon belly flaps was 7.5 times higher than in the loin (P<0.05), 1.8 times higher than in the pieces (P<0.05) and 30 times higher than in the fillet (P<0.05). Microbiological analysis showed that 32.5% (P<0.05) of the fish product samples were infected with L. monocytogenes, while multiplex PCR confirmed 31.25% positive samples (P<0.01). According to the study results, L. monocytogenes strains were divided into two serotypes: 4b (94.6%) and 1/2a (5.4%). High contamination of the products with Listeria spp. showed that cold smoked salmon products, sold in local market, can be a reason of human listeriosis in Lithuania.

Control of Growth and Survival of Listeria monocytogenes on Smoked Salmon by Combined Potassium Lactate and Sodium Diacetate and Freezing Stress during Refrigeration and Frozen Storage

2004 ◽  
Vol 67 (11) ◽  
pp. 2465-2471 ◽  
Author(s):  
K. S. YOON ◽  
C. N. BURNETTE ◽  
K. A. ABOU-ZEID ◽  
R. C. WHITING
Keyword(s):  
Listeria Monocytogenes ◽  
Frozen Storage ◽  
Storage Period ◽  
Freezing Stress ◽  
Growth And Survival ◽  
Smoked Salmon ◽  
Potassium Lactate ◽  
Sodium Diacetate ◽  
Kinetics Of ◽  
Different Levels

In this study, we evaluated the antimicrobial effects of different levels of a potassium lactate (PL) plus sodium diacetate (SDA) mixture against the growth and survival of Listeria monocytogenes Scott A inoculated onto smoked salmon stored at 4, 10, and −20°C. The effect of freezing stress on the growth kinetics of L. monocytogenes Scott A on smoked salmon at 4 and 10°C was also investigated. The use of PL+SDA at all tested levels (1.5, 3.3, and 5% of a 60% commercial solution of PURASAL P Opti.Form 4) completely inhibited the growth of L. monocytogenes Scott A on smoked salmon stored at 4°C during 32 days of storage. It also delayed the growth of L. monocytogenes Scott A on smoked salmon stored at 10°C for up to 11 days, but a listeriostatic effect was observed only with 5% PURASAL P Opti.Form 4 at 10°C after 11 days. Addition of PL+SDA at all tested levels decreased the surviving populations of L. monocytogenes Scott A on smoked salmon during 10 months of frozen storage at −20°C. Freezing stress significantly (P &lt; 0.001) extended the lag time and delayed the growth of L. monocytogenes Scott A at both 4 and 10°C. However, the effect of freezing stress was more significant at 4°C than at 10°C, indicating the importance of temperature control of smoked salmon during the retail storage period.

Tracing Listeria monocytogenes isolates from cold-smoked salmon and its processing environment in Iceland using pulsed-field gel electrophoresis

2005 ◽  
Vol 101 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Sigrún Gudmundsdóttir ◽  
Birna Gudbjörnsdóttir ◽  
Hélène L. Lauzon ◽  
Hjörleifur Einarsson ◽  
Karl G. Kristinsson ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Pulsed Field ◽  
Smoked Salmon

Parameters for Control of Listeria monocytogenes in Smoked Fishery Products: Sodium Chloride and Packaging Method

1993 ◽  
Vol 56 (11) ◽  
pp. 938-943 ◽  
Author(s):  
MARK E. PETERSON ◽  
GRETCHEN A. PELROY ◽  
ROHINEE N. PARANJPYE ◽  
FRANK T. POYSKY ◽  
JAMIE S. ALMOND ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Vacuum Packaging ◽  
Water Phase ◽  
Smoked Fish ◽  
Rate Of Growth ◽  
A Cells ◽  
Smoked Salmon ◽  
Nacl Concentration ◽  
Fishery Products

The behavior of Listeria monocytogenes (10 Scott A cells per g) in cold-process (smoked) salmon containing 3, 5, or 6% water-phase NaCl was evaluated during 30 to 40 d storage at 5 or 10°C in either oxygen-permeable film or vacuum-sealed impermeable film. At 10°C, L. monocytogenes grew to 106 to 108 CFU/g by the second week, with no differences attributed to NaCl concentration except for an initial lag in the 6% NaCl samples. Vacuum packaging suppressed growth of L. monocytogenes by 10- to 100-fold in samples with 3 or 5% NaCl. Inhibition related to NaCl concentration was most apparent at 5°C and L. monocytogenes populations were held below 102 CFU/g by 6% NaCl. Growth of a 327 CFU/g inoculum was about 10-fold greater than a 10 CFU/g inoculum at 10°C and 100-fold greater at 5°C. Growth of two strains isolated from naturally contaminated, commercially prepared, cold-smoked fish did not differ from Scott A. The use of sugar in the product did not influence growth of L. monocytogenes. Maximum populations of aerobic microorganisms reached at 5 and 10°C were similar, although the rate of growth was somewhat delayed at 5°C, and some inhibition was shown by 5 and 6% NaCl and by vacuum packaging.

Ribotype Analysis of Strain Distribution in Listeria monocytogenes

2000 ◽  
Vol 63 (2) ◽  
pp. 179-185 ◽  
Author(s):  
STEVEN M. GENDEL ◽  
JODIE ULASZEK
Keyword(s):  
Listeria Monocytogenes ◽  
Spatial Patterns ◽  
Strain Distribution ◽  
Foodborne Pathogen ◽  
Restriction Enzymes ◽  
Food Sample ◽  
Temporal And Spatial Patterns ◽  
Smoked Salmon ◽  
Temporal And Spatial ◽  
Multiple Strains

Changes in the temporal and spatial patterns of strain distribution for the foodborne pathogen Listeria monocytogenes were studied by ribotyping using the Qualicon Riboprinter system. Ribotype patterns were obtained by using the restriction enzymes EcoRI and PvuII for 72 isolates of L. monocytogenes recovered from smoked salmon samples over a period of 3 years. Each pattern was classified both by comparison to a pattern library and by comparison among the 72 isolate patterns. Eleven EcoRI-based ribogroups and 16 PvuII groups were identified. Eight of the 11 EcoRI ribogroups were found in isolates obtained over a period of &gt;12 months, and 75% of the EcoRI ribogroups that were found in more than one food sample were distributed nationally. Within the set of isolates, there were 26 instances where more than one isolate was obtained from a single food sample. In 35% of these instances, the co-isolates produced different ribotype patterns, indicating that multiple strains of L. monocytogenes commonly coexist in the same environment. Overall, these data indicate that the population of L. monocytogenes consists of a number of widely dispersed strains with little geographic or temporal stratification.

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