Wide variety of bioserotypes of enteropathogenic Yersinia in tonsils of English pigs at slaughter.

The tonsils of 630 pigs from 45 English farms using three different rearing methods (Assured British Pigs, Open Management and Organic) were examined between 2003 and 2005 in order to investigate if the low incidence of human yersiniosis could be attributed to a low prevalence of enteropathogenic Yersinia among English pigs. In addition, different isolation methods were compared, possible differences in prevalence among pigs were studied, as well as the prevalence of different bioserotypes of enteropathogenic Yersinia. A high prevalence and a wide diversity of bioserotypes of enteropathogenic Yersinia compared to other European countries were observed. The prevalence of pathogenic Yersinia enterocolitica was 44% and of Yersinia pseudotuberculosis 18%. Overall, 60% of pigs carried enteropathogenic Yersinia. Y. pseudotuberculosis was detected on 78% of farms and Y. enterocolitica on 69%. The most common bioserotypes of Y. enterocolitica were 2/O:9 (33%) and 2/O:5 (26%), and of Y. pseudotuberculosis 2/O:3 (34%), 1/O:1 (26%) and 1/O:4 (24%). Cold enrichment gave the highest isolation rate for both species. Y. enterocolitica was more prevalent (P<0.001) and Y. pseudotuberculosis less prevalent (P<0.05) in winter than in summer in Eastern England. Y. enterocolitica was more common in Eastern England and in assured British pigs, whereas Y. pseudotuberculosis was more common in Western England and in organic pigs. Y. pseudotuberculosis 1/O:1 was predominant (P<0.05) in Western England. Types 1/O:4 (P<0.05) and 2/O:3 (P<0.001) predominated in Eastern England. The high prevalence of Y. enterocolitica bioserotypes 2/O:9 and 2/O:5 found in this study suggests that English pigs are an important reservoir of these bioserotypes whereas in other European countries bioserotype 4/O:3 predominates.

Use of O-antigen gene cluster-specific PCRs for the identification and O-genotyping of Yersinia pseudotuberculosis and Yersinia pestis.

Yersinia pestis is a very recently evolved clone of Yersinia pseudotuberculosis serotype O:1b. This close relationship causes potential difficulties in DNA-based diagnostic methods. Analysis of the O-antigen gene clusters in these two organisms identified two regions that were used to specifically identify Y. pestis-Y. pseudotuberculosis as a group or Y. pestis alone. Both PCR assays were found to be 100% specific when tested on a large collection of Yersinia species and other Enterobacteriaceae. Furthermore, advantage was taken of the different setups of the O-antigen gene clusters of the 21 known Y. pseudotuberculosis serotypes to develop a multiplex PCR assay to replace the conventional serotyping method of Y. pseudotuberculosis by O-genotyping. The multiplex PCR assay contained nine sets of specific PCRs in a single tube and when used on Y. pseudotuberculosis reference strains allowed the distinction of 14 individual serotypes and two duplex serotypes (O:4a-O:8 and O:12-O:13). Serotype O:7, O:9, and O:10 strains required additional PCRs for O-genotyping. Once applied to Y. pseudotuberculosis strains of various origins, a very good correlation between classical serotypes and O-genotypes was observed, although some discrepancies were found. O-genotyping also proved useful to correct misidentification of some strains and to type Y. pseudotuberculosis isolates that had lost the expression of the O-antigen. The PCR-based O-genotyping can easily be applied in conventional laboratories, without the need for tedious preparation of a large set of specific antisera.

Yersiniosis: the clinical spectrum.

Although pathogenic Yersinia have been described several decades ago, human Yersinia infections remain enigmatic. The high prevalence in Europe and the variety of manifestations should be known to most clinicians. Both Yersinia enterocolitica and Y. pseudotuberculosis may cause similar clinical pictures. The clinical spectrum encompasses both intestinal and extraintestinal infectious syndromes and reactive or postinfectious immunological manifestations. The limited value of the currently available serodiagnostic techniques and the broad clinical spectrum make reactive yersiniosis a difficult diagnosis. Yersiniosis must be considered in the differential diagnosis of rheumatic and collagen vascular diseases. In selected indications the use of newer diagnostic tools such as immunoblotting and indirect immunofluorescence may increase the diagnostic yield in idiopathic reactive manifestations or recurrent or persisting infections of unknown origin. Recently, fluoroquinolones have emerged as promising drug when therapy is indicated.

Yersinia enterocolitica in food hygiene.

Yersinia enterocolitica and Yersinia enterocolitica-like bacteria constitute a fairly heterogenous group of bacteria which includes both well-established pathogens and a range of environmental strains which are ubiquitous in terrestrial and freshwater ecosystems. Pathogenic significance in man is mainly associated with a few serogroups (O:3, O:9, O:8, O:5,27). The pathogenic serogroups show different geographical distributions. The development of isolation procedures which clearly differentiate pathogenic from non-pathogenic variants has been difficult. Of special significance in food hygiene is the ability of Y. enterocolitica to grow in refrigerated foods. There is strong indirect evidence that pigs and food products of porcine origin are the major sources for human infection with Y. enterocolitica serogroups O:3 and O:9, the dominant human pathogens in most parts of the world. The reservoir(s) for serogroup O:8, which prevails in the U.S.A., is uncertain. The pig is the only animal consumed by man which regularly harbours pathogenic Y. enterocolitica. Improved isolation methods and DNA colony hybridization using genetic probes has indicated that the prevalence of pathogenic Y. enterocolitica in pork products is substantially higher than previously suggested. Prevention and control measures should focus on information of people involved in food processing and preparation and on the improvement of hygiene during slaughtering of swine. Important critical control points at the stage of slaughter are: (i) circumanal incision and removal of intestines, (ii) excision of the tongue, pharynx, and particularly the tonsils, (iii) post-mortem meat inspection procedures which involve incision of the mandibular lymph nodes, and (iv) deboning of head meat.

[Double infection with Yersinia enterocolitica 0:3 and 0:9]. / Doppelinfektion mit Yersinia enterocolitica 0:3 und 0:9.

An unusual case of Yersiniosis was observed in a 20-year-old woman. Except for an extraordinarily severe onset the clinical course was not remarkable. But two different strains of Yersinia were repeatedly isolated. While strain serotype 0:9 was demonstrated only transiently and gave an only weak immune reaction, serotype 0:3 persisted longer and stimulated a strong immune reaction. But both strains had similar virulence characteristics in different tests, such as plasmid demonstration, autoagglutination, growth on Ca-deficient agar, and in mice.

[Classification of acute bacterial enteropathies]. / Inquadramento e classificazione delle enteropatie batteriche acute.

The first part considers pathogenic microorganisms (Vibrio cholerae and parahaemolytic vibrio, Clostridium welchii, enteropathogenic E. coli, Shigella, Salmonella, other enterobacteria and pseudomonas. Yersinia, simply enterotoxic Staphylococcus and that producing acute enteritis) and the process of infection (formation of a surface link without endocellular penetration with elaboration of hexotoxins, formation of a surface link with subsequent intracellular penetration, submucosa penetration). The second part discusses Salmonellae on the basis of personal experience. Particular attention is paid to current aspects of Salmonella microbiological pathomorphosis, the various isolated serotypes in relation to carriers or patients, biochemical atypias of Salmonellae strains, present-day aspects of resistance to chemoantibiotic treatment and the transfer of Salmonella Wien resistances.