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Yersiniosis is the third most common reported zoonoses in Europe, with Y. enterocolitica and Y. pseudotuberculosis responsible for 98.66% and 0.94% of the confirmed human cases in 2013. From June 2013 to October 2014, 201 pigs at slaughter belonging to 67 batches were tested for Y. enterocolitica and Y. pseudotuberculosis in tonsils. Diaphragm muscle samples were tested for antibodies against Yersinia by a commercially available ELISA test. Y. enterocolitica 4/O:3 was detected in 55/201 pig tonsils (27.4%; 95% CI 23.1-37.1). The positive pigs came from 38/67 batches (56.7%) and were reared in 36/61 farms (59.0%). There was no statistical difference between farrow-to-finish and finishing farms. The mean count of Y. enterocolitica was 3.56±0.85log10CFU/g with a minimum of 2.0log10CFU/g and a maximum of 4.78log10CFU/g. Y. pseudotuberculosis was isolated from 4/201 pig tonsils (2.0%; 95% CI 0.0-4.5). Three isolates belonged to serotype O:3 and one to serotype O:1. The positive pigs belonged to 4/67 batches (6.0%) and came from finishing farms only. Y. pseudotuberculosis could be enumerated in one sample only (4.27log10CFU/g). The ELISA test demonstrated that 56.1% of the meat juice samples were positive for Yersinia antibodies. Serological positivity was found in 67.9% (36/53) of the Y. enterocolitica- and 75.0% (3/4) of the Y. pseudotuberculosis positive pigs. A significant association was found between serological results and the presence of Y. enterocolitica in tonsils (OR=1.97, p=0.044). All the Y. enterocolitica 4/O:3 isolates were susceptible to amoxicillin-clavulanic acid, gentamicin, ceftazidime, ertapenem and meropenem, 94.5% to cefotaxime, 89.1% to kanamycin and 78.2% to tetracycline. The highest resistance rates were observed for ampicillin (100%), sulphonamides (98.2%) and streptomycin (78.2%). Y. pseudotuberculosis strains were sensitive to all the antimicrobials tested, i.e. amoxicillin, amoxicillin/clavulanic acid, azithromycin, cephalothin, cefoxitin, ceftriaxone, ciprofloxacin, nalidixic acid, sulphonamide, tetracycline and ticarcillin. The study shows that Italian fattening pigs are frequently infected with human pathogenic Y. enterocolitica 4/O:3. Although the isolation rate is slightly lower than in other European countries, the serological test demonstrates that the infection is widespread among pig population. In fact, seroprevalence is similar to other EU countries. The detection of Y. pseudotuberculosis serotypes O:1 and O:3 in pig tonsils is of concern. Since tonsils may represent a contamination source for pig meat at slaughter, further studies regarding human infections by both microbial species are strongly recommended., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In 2005-2008, 1152 samples (451 faecal samples, 451 carcass swabs and 250 tonsils) were collected from 451 finishing pigs slaughtered in three abattoirs of northern Italy. In two abattoirs, 34 scalding water samples were collected. The aim of this study was to investigate the faecal and palatine tonsil carriage rate of Salmonella enterica and Yersinia enterocolitica in pigs at slaughter and the degree of carcass contamination by these bacteria. Typing of the isolates, virulence characterization and antimicrobial testing were also performed. S. enterica was isolated from 21.5% of the faecal samples, 10.9% of the carcasses and 10.4% of the tonsils, but not from scalding water. Nineteen different serovars were identified among 172 S. enterica isolates. The prevalent serovars were Derby (41.3%), Rissen (12.2%), Typhimurium (11%), 4,[5],12:i:- (8.7%) and Give (4.1%). S. enterica ser. Typhimurium and S. enterica ser. 4,[5],12:i:- isolates were phage-typed and PT DT120 was the most common (23.5%). Y. enterocolitica was detected in 17.1% of the faecal samples, 2.4% of the carcasses, 10.8% of the tonsils and 11.8% of the scalding water samples. A total of 119 isolates were found, four of them in water. Of the 115 Y. enterocolitica isolates of pig origin, 24 (20.9%) were 4/O:3 and 4 (3.5%) were 2/O:9. Y. enterocolitica 4/O:3 represented 85.7% of the pathogenic isolates found in all types of samples and 100% of those found in tonsils. In 4/O:3 isolates the most common virulence-associated genes were ystA (100%), inv (95.8%), ail (87.5%) and yadA (54.2%). In 2/O:9 isolates the prevalent genes were ail (100%), inv (100%) and ystA (100%), followed by ystB (25.0%). The majority (75.7%) of Y. enterocolitica isolates was biotype 1A, belonging to 13 serotypes (O:3; O:5; O:4,32-4,33; O:6,30-6,31; O:7,8-8; O:7,8-8-8,19; O:7,13; O:8; O:9; O:13; O:16-16,29; O:41,42-41,43; O:52). The most common virulence genes in 1A isolates were inv (95.4%) and ystB (72.4%). The antimicrobial resistance test showed that all Salmonella isolates were susceptible to cefotaxime, ciprofloxacin, cefalothin, gentamicin and enrofloxacin. Resistances to tetracycline (56%), sulphonamide compounds (42%) and streptomycin (34%) were the most common. All Y. enterocolitica isolates were susceptible to ciprofloxacin, ceftazidime, cefotaxime, chloramphenicol, enrofloxacin, gentamicin, kanamicin and neomycin. Most isolates were resistant to cefalothin (92%) and ampicillin (89%). Apparently, carcass contamination by S. enterica and Y. enterocolitica was more likely attributable to cross-contamination than to self-contamination, suggesting that good hygienic measures and slaughtering procedures can control transmission of these pathogens to pork meat., (Copyright © 2013 Elsevier B.V. All rights reserved.)

From December 1999 to December 2000, 150 pigs were randomly selected in two large abattoirs of northern Italy. Caecal material and carcass swabs were collected and examined for Salmonella, Yersinia enterocolitica, and Escherichia coli O157. Tonsils were examined for Salmonella and Y. enterocolitica. Salmonella was isolated from the intestinal content of 55 (36.7%) specimens, from 8 (5.3%) tonsils, and from 9 (6.0%) carcasses. Ten different serotypes were detected; the more common were Salmonella derby (37.8%), Salmonella bredeney (21.6%), and Salmonella typhimurium (14.8%). S. typhimurium isolates that belonged to phage-types DT104 and DT208 were 45% and 27.3%, respectively; 18.2% belonged to U302 and 9.1% were non-typeable. Y. enterocolitica was detected in the intestinal matter of 6 (4.0%) slaughtered pigs and in 22 (14.7%) tonsils; however, this pathogen was not found on carcasses. The majority of Y. enterocolitica isolates (82.1%) belonged to serotype O:3 biotype 4, one (3.6%) belonged to serotype O:9, and 13% did not belong to any known biotype. Verocytotoxin-producing E. coli (VTEC) O157 was isolated from the intestinal content of one (0.7%) slaughtered pig and from one (0.7%) carcass; four (2.7%) faecal samples contained E. coli O157 strains negative for the presence of both eae and VT genes.