title: Detection of Salmonella enterica in pigs at slaughter and comparison with human isolates in Italy.
abstract: In 2013-2014, 201 pigs belonging to 67 batches were tested for Salmonella in their mesenteric lymph nodes (MLN) in one abattoir of Northern Italy. For each batch, faecal material was collected at lairage by swabbing the pen floor for approximately 1600 cm(2). The aim of this study was to investigate the prevalence of Salmonella in MLN of pigs at slaughter, to assess Salmonella contamination at lairage and to evaluate the effect of lairage duration on its prevalence. Serotyping, XbaI PFGE typing and antimicrobial testing of the isolates were performed. Pig and human Salmonella isolates of the same region of Italy were compared to evaluate possible correlations. Salmonella enterica was isolated from 19.9% of the MLN and 49.3% of the environmental faecal samples. Nine different serovars were identified among 75 S. enterica isolates. In MLN Salmonella Derby was the most common (52.5%), followed by S. enterica 4,[5],12:i:- (17.5%) and Salmonella Rissen (10.0%). In faecal samples S. Derby was prevalent (51.4%), followed by S. enterica 4,[5], 12:i:- (20.0%) and Salmonella Brandenburg (14.3%). Lairage holding varied between 1 and ≥ 12 h (median value: 2.5h). In pigs held for 1-3h, 14.1% were positive for Salmonella in MLN but the prevalence reached 31.8% when they were held for ≥ 12 h. The contamination of MLN was statistically different (p=0.0045) between the two groups, thus confirming the role of long-lasting lairage in Salmonella contamination of pigs. XbaI PFGE typing detected 36 PFGE types. Twenty-three PFGE types were identified among the 40 MLN isolates and 22 PFGE types among the 35 faecal isolates. A total of 11 PFGE types were shared between the MLN of pigs and the lairage environment. Among S. Derby, 6 shared PFGE types between MLN and faeces were found and among S. enterica 4,[5],12:i:- one PFGE type was common between MLN and the faecal samples. Shared profiles between human and swine isolates of S. Derby, S. enterica 4,[5],12:i:-, S. Rissen, Salmonella Manhattan, S. Brandenburg, Salmonella Livingstone, Salmonella London and Salmonella Muenchen were identified. Among S. Derby and S. enterica 4,[5],12:i:- isolates found in pigs, 6/15 profiles (40.0%) and 8/10 (80.0%) were shared with human isolates. High resistance rates to streptomycin (97.3%), sulphonamide compounds (84.0%) and tetracycline (56.0%) were observed. No resistance was detected to ertapenem and meropenem. High proportions of isolates showed intermediate sensitivity to ciprofloxacin (85.3%) and cefotaxime (66.7%). High sensitivity rates were found to chloramphenicol (96.0%) and trimethoprim/sulfamethoxazole (81.3%).
authors.affiliation: Department of Veterinary Science, Unit of Food Hygiene, University of Parma, Via del Taglio 10, 43126 Parma, Italy. Electronic address: silvia.bonardi@unipr.it.
authors.forename: Silvia
authors.initials: S
authors.lastname: Bonardi
authors.affiliation: Department of Veterinary Science, Unit of Food Hygiene, University of Parma, Via del Taglio 10, 43126 Parma, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Alpigiani
authors.affiliation: Department of Veterinary Science, Unit of Food Hygiene, University of Parma, Via del Taglio 10, 43126 Parma, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Bruini
authors.affiliation: Department of Veterinary Science, Unit of Food Hygiene, University of Parma, Via del Taglio 10, 43126 Parma, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Barilli
authors.affiliation: Department of Veterinary Science, Unit of Food Hygiene, University of Parma, Via del Taglio 10, 43126 Parma, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Brindani
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Sezione di Parma, Strada dei Mercati 13/A, 43126 Parma, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Morganti
authors.affiliation: National Veterinary Service, Local Unit of Parma, Via Vasari 13/A, 43126, Parma, Italy.
authors.forename: Pierugo
authors.initials: P
authors.lastname: Cavallini
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Sezione di Parma, Strada dei Mercati 13/A, 43126 Parma, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bolzoni
authors.affiliation: Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Sezione di Parma, Strada dei Mercati 13/A, 43126 Parma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pongolini
mesh_terms: D000003:Abattoirs; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000502:physiology*; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008198:Lymph Nodes / Q000382:microbiology; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D019779:Salmonella enterica / Q000145:classification / Q000302:isolation & purification*; D012703:Serotyping; D013552:Swine / Q000382:microbiology*; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology; D013752:Tetracycline
chemical_list: D000900:Anti-Bacterial Agents; D013752:Tetracycline
keywords: Antimicrobial resistance; Human; PFGE; Pig; Salmonella