Yersinia enterocolitica palearctica serobiotype O:3/4 - a successful group of emerging zoonotic pathogens

<p>Abstract</p> <p>Background</p> <p>High-pathogenic <it>Y. enterocolitica </it>ssp. <it>enterocolitica </it>caused several human outbreaks in Northern America. In contrast, low pathogenic <it>Y. enterocolitica </it>ssp. <it>palearctica </it>serobiotype O:3/4 is responsible for sporadic cases worldwide with asymptomatic pigs being the main source of infection. Genomes of three <it>Y. enterocolitica </it>ssp. <it>palearctica </it>serobiotype O:3/4 human isolates (including the completely sequenced Y11 German DSMZ type strain) were compared to the high-pathogenic <it>Y. enterocolitica </it>ssp. <it>enterocolitica </it>8081 O:8/1B to address the peculiarities of the O:3/4 group.</p> <p>Results</p> <p>Most high-pathogenicity-associated determinants of <it>Y. enterocolitica </it>ssp. <it>enterocolitica </it>(like the High-Pathogenicity Island, <it>yts1 </it>type 2 and <it>ysa </it>type 3 secretion systems) are absent in <it>Y. enterocolitica </it>ssp. <it>palearctica </it>serobiotype O:3/4 genomes. On the other hand they possess alternative putative virulence and fitness factors, such as a different <it>ysp </it>type 3 secretion system, an RtxA-like and insecticidal toxins, and a N-acetyl-galactosamine (GalNAc) PTS system (<it>aga</it>-operon). Horizontal acquisition of two prophages and a tRNA-Asn-associated GIYep-01 genomic island might also influence the <it>Y. enterocolitica </it>ssp. <it>palearctica </it>serobiotype O:3/4 pathoadaptation. We demonstrated recombination activity of the PhiYep-3 prophage and the GIYep-01 island and the ability of the <it>aga</it>-operon to support the growth of the <it>Y. enterocolitica </it>ssp. <it>enterocolitica </it>O:8/1B on GalNAc.</p> <p>Conclusions</p> <p><it>Y. enterocolitica </it>ssp. <it>palearctica </it>serobiotype O:3/4 experienced a shift to an alternative patchwork of virulence and fitness determinants that might play a significant role in its host pathoadaptation and successful worldwide dissemination.</p

Shotgun sequencing of Yersinia enterocolitica strain W22703 (biotype 2, serotype O:9): genomic evidence for oscillation between invertebrates and mammals

<p>Abstract</p> <p>Background</p> <p><it>Yersinia enterocolitica </it>strains responsible for mild gastroenteritis in humans are very diverse with respect to their metabolic and virulence properties. Strain W22703 (biotype 2, serotype O:9) was recently identified to possess nematocidal and insecticidal activity. To better understand the relationship between pathogenicity towards insects and humans, we compared the W22703 genome with that of the highly pathogenic strain 8081 (biotype1B; serotype O:8), the only <it>Y. enterocolitica </it>strain sequenced so far.</p> <p>Results</p> <p>We used whole-genome shotgun data to assemble, annotate and analyse the sequence of strain W22703. Numerous factors assumed to contribute to enteric survival and pathogenesis, among them osmoregulated periplasmic glucan, hydrogenases, cobalamin-dependent pathways, iron uptake systems and the <it>Yersinia </it>genome island 1 (YGI-1) involved in tight adherence were identified to be common to the 8081 and W22703 genomes. However, sets of ~550 genes revealed to be specific for each of them in comparison to the other strain. The plasticity zone (PZ) of 142 kb in the W22703 genome carries an ancient flagellar cluster Flg-2 of ~40 kb, but it lacks the pathogenicity island YAPI_Ye, the secretion system <it>ysa </it>and <it>yts1</it>, and other virulence determinants of the 8081 PZ. Its composition underlines the prominent variability of this genome region and demonstrates its contribution to the higher pathogenicity of biotype 1B strains with respect to W22703. A novel type three secretion system of mosaic structure was found in the genome of W22703 that is absent in the sequenced strains of the human pathogenic <it>Yersinia </it>species, but conserved in the genomes of the apathogenic species. We identified several regions of differences in W22703 that mainly code for transporters, regulators, metabolic pathways, and defence factors.</p> <p>Conclusion</p> <p>The W22703 sequence analysis revealed a genome composition distinct from other pathogenic <it>Yersinia enterocolitica </it>strains, thus contributing novel data to the <it>Y. enterocolitica </it>pan-genome. This study also sheds further light on the strategies of this pathogen to cope with its environments.</p

Yersinia enterocolitica in sheep - a high frequency of biotype 1A

BACKGROUND: Pigs are regarded as the main reservoir for human pathogenic Yersinia enterocolitica, which is dominated by bioserotype 4/O:3. Other animals, including sheep, have occasionally been reported as carriers of pathogenic strains of Y. enterocolitica. To our knowledge, this is the first study performed in the Nordic countries in which the presence of Y. enterocolitica in sheep is investigated. METHODS: Tonsils and faecal samples collected from sheep slaughtered on the island Gotland (Sweden) from September 2010 through January 2011 were analysed for presence of Y. enterocolitica. In an attempt to maximize recovery, several cultural strategies were applied. Various non-selective media were used and different temperatures and durations of the enrichment were applied before subculturing on Cefsulodin Irgasan Novobiocin (CIN) agar. Presumptive Y. enterocolitica colonies were subjected to urease, API 20E and agglutination test. Yersinia enterocolitica isolates were biotyped, serotyped, and tested for pathogenicity using a TaqMan PCR directed towards the ail-gene that is associated with human pathogenic strains of Y. enterocolitica. RESULTS: The samples collected from 99 sheep yielded 567 presumptive Y. enterocolitica colonies. Eighty urease positive isolates, from 35 sheep, were identified as Y. enterocolitica by API 20E. Thirty-four of 35 further subtyped Y. enterocolitica isolates, all from faecal samples, belonged to biotype 1A serotype O:5, O:6. O:13,7 and O:10. One strain was Yersinia mollaretii serotype O:62. No human pathogenic strains of Y. enterocolitica were found in the investigated sheep. Other species identified were Y. kristensenii (n=4), Y. frederiksenii/intermedia (n =3), Providencia rettgeri (n= 2), Serratia marcescens (n =1) and Raoultella ornithinolytica (n=1). CONCLUSIONS: This study does not support the hypothesis that sheep play an important role in transmission of the known human pathogenic Y. enterocolitica in the studied geographical region. However, because there are studies indicating that some strains of Y. enterocolitica biotype 1A may cause disease in humans, the relative importance of sheep as carriers of human pathogenic strains of Y. enterocolitica remains unclear. Tonsils do not appear to be favourable sites for Y. enterocolitica biotype 1A in sheep

Characteristics of Yersinia enterocolitica biotype 1A strains isolated from patients and asymptomatic carriers

Yersinia enterocolitica biotype 1A strains are frequently isolated from the environment, foods, and animals, and also from humans with yersiniosis. There are controversial reports on the pathogenicity of biotype 1A strains. In this study, 811 fecal samples from asymptomatic humans from Switzerland were studied for the presence of Y. enterocolitica. Nine (1.1%) of the 811 samples were positive for Y. enterocolitica 1A. These strains were compared with 12 Y. enterocolitica 1A strains from Swiss patients with diarrhea isolated in the same year. Almost all (20/21) Y. enterocolitica 1A strains carried the ystB gene, seven strains carried the hreP gene, and none carried the ail, ystA, myfA, yadA, or virF genes. Most (17/21) Y. enterocolitica 1A strains belonged to two major clusters, A and B, by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Strains of cluster B were only isolated from humans with diarrhea; however, ystB and hreP genes were detected in strains from both clinical and non-clinical samples and from strains of clusters A and B. Using ribotyping, six restriction patterns among biotype 1A strains were obtained with HindIII enzyme. The most common ribotype (RT I) was found in strains isolated from humans with and without diarrhea. All biotype 1A strains had a unique NotI profile by pulsed-field gel electrophoresis (PFGE), showing a very high genetic diversity. In this study, Y. enterocolitica 1A strains from clinical and non-clinical samples could not be clearly differentiated from each other. More research is needed in order to prove that biotype 1A strains are a primary cause for human yersiniosis and not only a secondary finding