Variation in the Prevalence of EnteropathogenicYersiniain Slaughter Pigs from Belgium, Italy, and Spain

Abstract

Tonsils of 829 fattening pigs originating from Belgium (n ¼ 201), Italy (n ¼ 428), and Spain (n ¼ 200) were collected between 2005 and 2007 to study the prevalence of enteropathogenic Yersinia in slaughter pigs. Isolation of Yersinia enterocolitica and Yersinia pseudotuberculosis was done by selective enrichment and by cold enrichment for 7 and 14 days. Pathogenic Y. enterocolitica and Y. pseudotuberculosis isolates were identified by polymerase chain reaction targeting the chromosomal genes ail and inv, respectively, as well as the plasmid-encoded virF of both species. A significantly higher ( p < 0.001) prevalence of ail-positive Y. enterocolitica in Spain (93%) than in Belgium (44%) or Italy (32%) was observed. virF-positive Y. enterocolitica was present in 77% of ail-positive samples. Bioserotype 4=O:3 was the most common type in all three countries. Bioserotypes 2=O:5 and 3=O:9 were found in Italy (1%) and Belgium (9%), respectively. The prevalence of inv-and virF-positive Y. pseudotuberculosis was 2% and 1% in Belgium and Italy, respectively. Y. pseudotuberculosis was not detected in pigs from Spain. Bioserotypes 1=O:1 (20%), 1=O:2 (20%), and 2=O:3 (60%) were found in Belgium, and 1=O:1 (60%) and 2=O:3 (20%) in Italy. The most efficient method for isolation of Y. enterocolitica was combined cold enrichment for 7 and 14 days; however, the isolation method for Y. pseudotuberculosis was cold enrichment for 14 days. Fattening pigs seem to be an important reservoir of pathogenic Y. enterocolitica in Belgium, Italy, and Spain. Bioserotype 4=O:3 of Y. enterocolitica and bioserotypes 2=O:3 and 1=O:1 of Y. pseudotuberculosis have been shown to predominate.

Different EnteropathogenicYersiniaStrains Found in Wild Boars and Domestic Pigs

“…pseudotuberculosis strains were only isolated from wild boars in Switzerland. However, it has recently been shown that Y. pseudotuberculosis can also be found in domestic pigs but that the prevalence is clearly lower than the prevalence of Y. enterocolitica (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. Further studies are needed to show that wild boars are a more important reservoir for Y. pseudotuberculosis than domestic pigs.…”

“…Bioserotype 4=O:3 is widely distributed and the most common type causing human yersiniosis in Europe (EFSA, 2009). It is also the most common type in European pig population (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. Bioserotype 2=O:9 is the second most common type identified in human yersiniosis in Europe followed by bioserotype 2=O:5,27.…”

“…Pigs are considered to be the main reservoir of human pathogenic Y. enterocolitica strains carrying this pathogen frequently in the tonsils at slaughter (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. Y. pseudotuberculosis has also been isolated from fattening pigs but with lower prevalences as Y. enterocolitica (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b.…”

“…Pigs are considered to be the main reservoir of human pathogenic Y. enterocolitica strains carrying this pathogen frequently in the tonsils at slaughter (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. Y. pseudotuberculosis has also been isolated from fattening pigs but with lower prevalences as Y. enterocolitica (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. Pathogenic Y. enterocolitica and Y. pseudotuberculosis can easily be detected and identified using polymerase chain reaction (PCR) targeting the chromosomally encoded virulence genes ail and inv, respectively (Fredriksson-Ahomaa et al, 2007;Bhaduri et al, 2009;Niskanen et al, 2009).…”

“…Only Y. enterocolitica strains belonging to bioserotype 4=O:3 and Y. pseudotuberculosis strains of bioserotype 2=O:3 have repeatedly been isolated from fattening pigs at slaughter in Europe (Martínez et al, 2009(Martínez et al, , 2010a(Martínez et al, , 2010b. A high genetic similarity between human and porcine Y. enterocolitica 4=O:3 strains has been shown by PFGE using NotI, ApaI, and XhoI enzymes, indicating that pigs are an important reservoir for human pathogenic Y. enterocolitica 4=O:3 strains (Fredriksson-Ahomaa et al, 2006).…”