title: Listeria monocytogenes in Smoked Salmon and Other Smoked Fish at Retail in Italy: Frequency of Contamination and Strain Characterization in Products from Different Manufacturers.
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 ×106CFU/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.
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Vicdalia Aniela
authors.initials: VA
authors.lastname: Acciari
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Torresi
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Iannetti
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Scattolini
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pomilio
authors.affiliation: Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, 10154 Torino, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Decastelli
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna "B. Ubertini," Via Bianchi 9, 25124 Brescia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Colmegna
authors.affiliation: Istituto Zooprofilattico Sperimentale delle Venezie, via dell'Università 10, 35020 Legnaro (PD), Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Muliari
authors.affiliation: Istituto Zooprofilattico Sperimentale del Lazio e della Toscana "M. Aleandri," Via Appia Nuova 1411, 00178 Rome, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Bossù
authors.affiliation: Istituto Zooprofilattico Sperimentale del Mezzogiorno, Via della Salute 11, 80055 Portici (NA), Italy.
authors.forename: Yolande
authors.initials: Y
authors.lastname: Proroga
authors.affiliation: Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Via Manfredonia 20, 71121 Foggia, Italy.
authors.forename: Cosimo
authors.initials: C
authors.lastname: Montagna
authors.affiliation: Istituto Zooprofilattico Sperimentale della Sicilia "A. Mirri," Via G. Marinuzzi 3, 90129 Palermo, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Cardamone
authors.affiliation: Istituto Zooprofilattico Sperimentale della Sardegna "G. Pegreffi," Via Duca degli Abruzzi 8, 07100 Sassari, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Cogoni
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Vincenza Annunziata
authors.initials: VA
authors.lastname: Prencipe
authors.affiliation: National Reference Laboratory for Listeria monocytogenes, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale," Campo Boario, 64100 Teramo, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Migliorati
mesh_terms: D000818:Animals; D016521:Electrophoresis, Gel, Pulsed-Field; D005506:Food Contamination; D005516:Food Microbiology; D006801:Humans; D007558:Italy; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D012474:Salmon; D012703:Serotyping; D012906:Smoke
chemical_list: D012906:Smoke
keywords: Listeria monocytogenes; Manufacturer; Pulsed-field gel electrophoresis; Retail; Serotyping; Smoked salmon