Exploring Yersinia ruckeri (O1 Biotype 2) infection in three early life-stages of rainbow trout.

Enteric redmouth disease (ERM) caused by the enterobacterium Yersinia ruckeri poses a significant threat to salmonid aquaculture globally. Despite decades of experimental infection studies, key knowledge gaps remain regarding the onset of disease susceptibility and mechanisms of immunity during early developmental stages, undermining disease management efforts in all susceptible life-stages. In this study, a series of immersion challenges were conducted, challenging and re-challenging rainbow trout Oncorhynchus mykiss (Walbaum) at 7, 14 and 51 d post-hatch (dph; mean weights = 0.085, 0.1 and 2.0 g respectively) to high concentrations (1.72 × 107-1.1 × 108 CFU) of Y. ruckeri at 15°C. This study indicates the hitherto unknown initial point of susceptibility to infection as the time of first ingestion of exogenous food (14 dph), and shows that individuals surviving primary challenge at 14 dph are significantly more likely to survive re-challenge at 51 dph compared with naive individuals (hazard ratio = 1.446, p = 0.032). Other key findings include large variation in mortality between different development-stages, from 21.1% at 14 dph to 81.2% at 51 dph, and novel age-dependent symptoms not reported previously. Results from this study enhance our understanding of ERM in juvenile rainbow trout and inform the development of improved aquatic animal health management strategies, thereby contributing to the productivity and sustainability of salmonid aquaculture into the future.

Co-existence of two Yersinia ruckeri biotypes and serotype O1a retrieved from rainbow trout (Oncorhynchus mykiss) farmed in Puno, Peru.

Yersinia ruckeri causes important economic losses for rainbow trout (Oncorhynchus mykiss) farms worldwide. This bacterial disease is likely the most common among trout in Peru; however, no commercial vaccine is available nationally, which is, in part, due to a lack of information on the bacterium. The aim of the current study was to characterize 29 Y. ruckeri isolates sampled from seven cage-reared farms in the Puno Region, the focal point for aquaculture activities in Peru. For this, samples were taken from fish with clinical signs (i.e. haemorrhages, uni- or bilateral exophthalmia, hyphaemia and/or melanosis). Notable among our findings was the existence of both Y. ruckeri biotype 1 (9 isolates) and biotype 2 (20 isolates; negative for sorbitol and Tween 80). The isolates further differed in API profiles 5307100 (21 isolates), 1307100 (4 isolates), 1305100 (2 isolates), 1307120 (1 isolate) and 5305100 (1 isolate), with the main differences being in the tests for lysine decarboxylase, gelatine hydrolysis and D-saccharose fermentation. Despite these differences, all isolates shared identical ERIC-PCR and REP-PCR profiles and belonged to the O1a serotype. Fingerprints were identical to the reference strain CECT 955 (serotype O1a). The information obtained will be used for epidemiological purposes by health authorities and for the development of a vaccine against Y. ruckeri, a prominent request made by fish farmers in Peru.

Biotyping reveals loss of motility in two distinct Yersinia ruckeri lineages exclusive to Norwegian aquaculture.

Non-motile strains of Yersinia ruckeri, known as Y. ruckeri biotype 2, now dominate amongst clinical isolates retrieved from rainbow trout internationally. Due to an acute increase in the number of yersiniosis cases in Norway in recent years, followed by introduction of widespread intraperitoneal vaccination against the disease, an investigation on the prevalence of Y. ruckeri biotype 2 in Norwegian aquaculture was conducted. We biotyped 263 Y. ruckeri isolates recovered from diseased salmonids in Norway between 1985 and 2020. A total of seven biotype 2 isolates were identified, four of which were collected between 1985 and 1987, and three of which belong to the current epizootic clone, isolated from two different sea-farms in 2017. Whole-genome sequencing revealed single non-synonymous nucleotide polymorphisms in the flagellar genes flhC in isolates from the 1980s, and in fliP in isolates from 2017. In both variants, motility was restored both by complementation with wild-type alleles in trans and via spontaneous mutation-driven reversion following prolonged incubation on motility agar. While biotype 2 strains do not yet seem to have become broadly established in Norwegian aquaculture, the seven isolates described here serve to document a further two independent cases of Y. ruckeri biotype 2 emergence in salmonid aquaculture.

Functional and Molecular Immune Response of Rainbow Trout (Oncorhynchus mykiss) Following Challenge with Yersinia ruckeri.

Currently, aquaculture production of rainbow trout (Oncorhynchus mykiss) is a multibillion dollar industry; nevertheless, the development of this sector has not been exempt from pitfalls related to the recurrent presence of pathogens of bacterial origin. This is the case of Yersinia ruckeri, the etiologic agent of the infectious pathology known as Enteric Red Mouth Disease (ERM), causing serious economic losses that can be as high as 30-70% of production. Although several studies have been performed regarding pathogen features and virulence factors, more information is needed about the host defense mechanism activation after infection. Given this perspective, this study aimed to evaluate rainbow trout's short-term innate immune response against infection with Y. ruckeri. A series of factors linked to the innate immune response were evaluated, including determination of hematological parameters, oxidative stress biomarkers, and analysis of the expression of immune-related genes. Results showed a significant decrease in several hematological parameters (white blood cell count, hematocrit, neutrophils, monocytes, lymphocytes, and thrombocytes) and oxidative stress indicators (SOD) between the control and infected groups. In addition, there were significant differences in the level of gene expression between infected individuals and the control group. Most of these genes (il-1ß, il-8, il-10, tnf-α1, tnf-α2, socs3, mmp-9, cath, hsp-70, saa, fer, pcb) were upregulated within the first 24 h following infection. Results from this study showed more insights into the short-term immune response of rainbow trout to infection with Y. ruckeri, which may be useful for the establishment of biomarkers that may be used for the early detection of ERM.

Overview of basic epidemiological characteristics and descriptive analysis of the incidence of human yersiniosis in the Czech Republic in 2018-2020.

OBJECTIVE: The aim was to provide an overview of the basic epidemiological characteristics of human yersiniosis and to analyze the reported epidemiological data on the incidence of this disease in the Czech Republic (CZ) in 2018-2020. METHODS: A descriptive analysis was performed of cases of yersiniosis captured in the Infectious Disease Information System (ISIN) in the CZ in 2018-2020. MS Excel 2010 was used for data processing and sorting. RESULTS: In the CZ, a total of 1,686 cases of yersiniosis were reported in 2018-2020 (average annual incidence of 5/100,000 population). The highest average age-specific incidence was recorded in the age group 1-4 years (31.3/100,000), followed by 0-year-olds (26.9/100,000). In the study period, 942 cases were male and 744 cases were female, with the respective incidences of 6.0 /100,000 and 4.6/100,000. By administrative region, the highest average annual incidences were recorded in the South Moravian (9.1/100,000) and Moravian-Silesian (7.5/100,000) Regions. Hospital admission was required for 14.3% (n = 241) of reported cases. No death or outbreak was reported during the study period. A total of 31 cases were imported from usual recreational destinations. No seasonality was detected in the CZ; however, more cases always occur in January and in the second half of the year. Over the last three years, a stagnant trend in the incidence of the disease has been observed in the CZ. CONCLUSIONS: In 2018 and 2019, yersiniosis (caused by Y. enterocolitica and rarely Y. pseudotuberculosis) was the fourth most commonly reported zoonosis in humans in the European Union (EU), with a stable trend in 2014-2019. The CZ reports an incidence up to three times higher but a 2.5 lower share of hospitalized patients compared to the EU average, which probably indicates that the CZ has an effective surveillance system in place. The trend in the incidence of the disease has stagnated in the CZ and the EU in recent years. The most common vehicle for transmission of yersiniosis to humans is contaminated food, especially undercooked pork, less often vegetables or water. Contamination of products from home slaughtered animals intended for private consumption is likely and would also explain the increased incidence of the disease, particularly in the winter months.

Yersiniosis in Poland in 2018-2020.

AIM: The aim of the study was to assess the epidemiological situation of yersiniosis in Poland in 2018-2020 and compare it to previous years. MATERIAL AND METHODS: To assess the epidemiological situation of yersiniosis in Poland, data from individual case reports prepared by Sanitary Epidemiological Stations as part of routine epidemiological surveillance were used. Incidence, number of cases and data on hospitalizations by voivodship included in the bulletins "Infectious Diseases and Poisons in Poland" for 2015-2020 were also used. RESULTS: In 2018-2020, a total number of 542 cases of yersiniosis were registered, including 456 intestinal and 86 extraintestinal forms. The incidence in 2018 was 0.53/100,000 in 2019 0.59/100,000 and in 2020 0.29/100,000. The number of cases in 2020 compared to 2019 decreased by 52%, and compared to 2018 by 45.8%. The percentage of hospitalizations in each year was at a similar level of 65.5% in 2018, 62.4% in 2019, and 60% in 2020. The highest incidence was noted in the 0-4 age group at 44.7% of cases in 2018, 42.9% in 2019 and 55.6% in 2020, respectively (all cases of the intestinal form). The predominant species was Y. enterocolitica in both intestinal and extraintestinal forms. The most common serotype was serotype O:3, which was identified in 34 isolates in 2018, 43 isolates in 2019 and 9 isolates in 2020. SUMMARY AND CONCLUSIONS: Since 2009, Poland has had a decreasing trend in the incidence of yersiniosis. In 2020, both Poland and Europe saw a sharp decline in the number of cases compared to previous years. This is a result of the occurrence of the COVID-19 pandemic in March 2020, during which many measures were introduced to limit the spread of the SARS-CoV-2 virus, which may also have affected the number of other infections. Although the numbers of cases and incidence of yersiniosis among children under the age of 5 are the highest compared to other age groups, the highest number of hospitalizations was reported in the 10-19 age group, which most likely reflects the decreasing number of laboratory tests ordered on an outpatient basis with age and the significant underreporting of cases in this and older age groups.

Yersinia canariae sp. nov., isolated from a human yersiniosis case.

A Gram-negative rod from the Yersinia genus was isolated from a clinical case of yersiniosis in the United Kingdom. Long read sequencing data from an Oxford Nanopore Technologies (ONT) MinION in conjunction with Illumina HiSeq reads were used to generate a finished quality genome of this strain. Overall Genome Related Index (OGRI) of the strain was used to determine that it was a novel species within Yersinia, despite biochemical similarities to Yersinia enterocolitica. The 16S ribosomal RNA gene accessions are MN434982-MN434987 and the accession number for the complete and closed chromosome is CP043727. The type strain is SRR7544370T (=NCTC 14382T/=LMG 31573T).

RETROSPECTIVE REVIEW OF MORTALITY IN CAPTIVE PINK PIGEONS (NESOENAS MAYERI) HOUSED IN EUROPEAN COLLECTIONS: 1977-2018.

The Mauritian pink pigeon (Nesoenas mayeri) is vulnerable, with only 400 individuals remaining in the free-living population. A European captive population was established in 1977 and a European Endangered Species Program (EEP) in 1992. The EEP long-term management plan recommends integrating the EEP and free-living Mauritius populations through pigeon transfers. A retrospective mortality review of the captive population was performed as part of a disease risk assessment process and to inform infectious disease screening prior to exporting captive birds to Mauritius. Six hundred pink pigeons from 34 institutions died from 1977 to 2018. Each individual was categorized according to age at time of death. Records from 404 individuals were categorized according to cause of death. Neonatal mortality (39%) and juvenile mortality (10.8%) were most commonly caused by noninfectious diseases (52% and 54.4%, respectively), including parental neglect and failure to thrive in neonates and nutritional secondary hyperparathyroidism in juveniles. Trauma (43.1%) was the most common cause of mortality in adults, with significantly higher mortality in males from interspecific aggression and in females due to intraspecific aggression. Yersinia pseudotuberculosis, Mycobacterium avium, and Escherichia coli were the most common infectious causes of adult mortality, and E. coli was the most common infectious cause in neonates. The following infectious diseases were identified as priorities for pre-export disease risk analysis, though not all caused mortality: Y. pseudotuberculosis, M. avium, Trichomonas spp., Chlamydia psittaci, and Coccidia spp. Husbandry changes have been made over the years to mitigate many of the noninfectious causes of mortality. These include alterations to nest sites to reduce neonatal trauma and abandonment, ultraviolet light supplementation and diet optimization to reduce metabolic disorders, improving enclosure design to reduce impact trauma, allowing females rest periods during breeding season, and avoiding housing with certain species.

A Recombinant Attenuated Yersinia pseudotuberculosis Vaccine Delivering a Y. pestis YopENt138-LcrV Fusion Elicits Broad Protection against Plague and Yersiniosis in Mice.

In this study, a novel recombinant attenuated Yersinia pseudotuberculosis PB1+ strain (χ10069) engineered with ΔyopK ΔyopJ Δasd triple mutations was used to deliver a Y. pestis fusion protein, YopE amino acid 1 to 138-LcrV (YopENt138-LcrV), to Swiss Webster mice as a protective antigen against infections by yersiniae. χ10069 bacteria harboring the pYA5199 plasmid constitutively synthesized the YopENt138-LcrV fusion protein and secreted it via the type 3 secretion system (T3SS) at 37°C under calcium-deprived conditions. The attenuated strain χ10069(pYA5199) was manifested by the establishment of controlled infection in different tissues without developing conspicuous signs of disease in histopathological analysis of microtome sections. A single-dose oral immunization of χ10069(pYA5199) induced strong serum antibody titers (log10 mean value, 4.2), secretory IgA in bronchoalveolar lavage (BAL) fluid from immunized mice, and Yersinia-specific CD4+ and CD8+ T cells producing high levels of tumor necrosis factor alpha (TNF-α), gamma interferon (IFN-γ), and interleukin 2 (IL-2), as well as IL-17, in both lungs and spleens of immunized mice, conferring comprehensive Th1- and Th2-mediated immune responses and protection against bubonic and pneumonic plague challenges, with 80% and 90% survival, respectively. Mice immunized with χ10069(pYA5199) also exhibited complete protection against lethal oral infections by Yersinia enterocolitica WA and Y. pseudotuberculosis PB1+. These findings indicated that χ10069(pYA5199) as an oral vaccine induces protective immunity to prevent bubonic and pneumonic plague, as well as yersiniosis, in mice and would be a promising oral vaccine candidate for protection against plague and yersiniosis for human and veterinary applications.

Assessment of the efficacy of an autogenous vaccine against Yersinia pseudotuberculosis in young Merino sheep.

AIMS To assess the efficacy of an autogenous vaccine against Yersinia pseudotuberculosis III in preventing clinical disease and deaths due to yersiniosis in young Merino sheep, and to determine the effect of vaccination on the prevalence of faecal shedding of pathogenic Yersinia spp., daily liveweight gain, and development of antibodies to Yersinia spp. following vaccination and natural exposure. METHODS In six groups (three groups each from two farms) of young Merino sheep, 148-150 animals were systematically allocated to be vaccinated twice with an autogenous, formalin- killed bacterin vaccine containing Y. pseudotuberculosis serotype III or to remain non-vaccinated. All vaccinated and non-vaccinated sheep were run together in their original groups throughout the trial. Faecal and blood samples were collected, and liveweight measured, at the time of vaccination and subsequently over a 6-month period to determine faecal shedding of Y. enterocolitica and Y. pseudotuberculosis, seroprevalence of antibodies to Yersinia outer membrane proteins (YOP) and changes in liveweight. RESULTS None of the six trial groups experienced an outbreak of clinical yersiniosis during the study period. On Farm A, the prevalence of shedding of either or both Yersinia spp. was <40% on all but one sampling occasions. On Farm B the prevalence of shedding of both Yersinia spp. peaked at 98%, 96 days after vaccination. Mean liveweight and daily liveweight gain at the end of the study were similar in vaccinated and non-vaccinated groups on both farms (p>0.1), as was the prevalence of faecal shedding of Yersinia spp. (p>0.2), and the proportion of animals that became seropositive for antibodies to YOP following vaccination (p>0.1). CONCLUSIONS AND CLINICAL RELEVANCE This vaccine had, at most, limited effects on seroconversion and, under the conditions of this study, had no demonstrable impact on liveweight, mean daily liveweight gain or faecal shedding of Yersinia spp. Further studies are needed to determine the efficacy of this vaccine during outbreaks of yersiniosis or following experimental challenge with pathogenic Yersinia spp..

[The surveillance of Yersiniosis among children in central area of Beijing from 2011 to 2018].

Objective: To illuminate the epidemic characteristics of Yersiniosis among children in the central city of Beijing and the accuracy of current clinical diagnosis towards Yersiniosis. Methods: Etiological surveillance of diarrheal patients, a total of 3 493 cases, was performed in a children hospital in central area of Beijing from 2011 to 2018 continuously. Collected the epidemiological and clinical information of the cases, analyzed the clinical and etiological diagnosis for Yersiniosis and bacterial dysentery and compared the distribution of Yersiniosis cases with the different symptoms. Results: A total of 3 493 acute diarrhea cases distributed from the age of 6 months to 13 years old, M (P(25), P(75)) was 1.50 (0.75, 3.17) years old. The 28 cases were isolated Yersinia enterocolitica (isolation rate of 0.80%) and they could be diagnosed as Yersiniosis by etiology. The isolation peaked in May and February. A total of 85.71% (24/28) of Yersiniosis cases were under 5-year old. The children of 3-4 age group had the highest isolation rate (1.52%) while the rate (0.18%) of 0-1 age group was the lowest (P=0.025). The Yersinia enteroclitica isolation rates of diarrheal patients with the symptoms including mucus feces, fever, white blood cell (WBC) and red blood cell (RBC) in feces were higher than the patients without these symptoms (P>0.05). The 9 of 28 Yersiniosis cases by etiology diagnosis were clinical diagnosed as bacillary dysentery. Conclusion: The infants and young children under 5-year old were the main population of Yersiniosis adolescent patients under 14-year old. The typical symptoms characterized with mucus stool, fever, WBC and RBC by routine microscopic examination. The preliminary clinical diagnosis of Yersiniosis is easily confused with bacterial dysentery.

Yersiniosis in Poland in 2017

AIM: The aim of the study is to assess epidemiological situation of yersiniosis in Poland in 2017 in comparison to previous years. MATERIAL AND METHODS: The evaluation is based on analysis of data from the annual bulletins "Infectious diseases and poisoning in Poland", information from individual yersiniosis case reports entered and shared by local sanitary-epidemiological stations through Electronic Registry of Epidemiologic Forms (SRWE), information from individual extraintestinal case reports fulfilled by local sanitary-epidemiological station and sent to the Departments of Epidemiology, National Institute of Public Health - National Institute of Hygiene by regional sanitary-epidemiological stations, information on outbreaks shared through the Electronic Registry of Epidemic Outbreaks (ROE) and data on deaths from the Department of Demographic Studies of the Central Statistical Office. RESULTS: In 2017 255 cases of yersiniosis, including 191 intestinal and 64 extraintestinal were registered. Incidence in 2017 was 0.66/100 000 population. Number of cases registered in 2017 was higher than in 2015 and 2016 (for both years 205 cases with incidence 0.53/100 000 was observed) and similar to the one in 2014 (244 cases, incidence 0.63/100 000). In 2017 all intestinal yersiniosis cases met criteria for confirmed case. Around 35% of cases were registered in mazowieckie voivodship where incidence was similar to the one in European Union. Among Y. enterocolitica isolates, serotype was determined in 62 cases what stands for only 28.7% of all cases. Predominant serotype was 03, it was identified in 81% of serotyped cases. Most of intestinal yersiniosis cases occurred among children under 4 years (54.5% of all registered cases). CONCLUSIONS: In 2017 increase in number of cases was observed. Yersiniosis in Poland is rarely diagnosed, incidence in Poland is more than twice time lower than in European Union.

Multilocus Variable-Number Tandem-Repeat Analysis of Yersinia ruckeri Confirms the Existence of Host Specificity, Geographic Endemism, and Anthropogenic Dissemination of Virulent Clones.

A multilocus variable-number tandem-repeat analysis (MLVA) assay was developed for epizootiological study of the internationally significant fish pathogen Yersinia ruckeri, which causes yersiniosis in salmonids. The assay involves amplification of 10 variable-number tandem-repeat (VNTR) loci in two five-plex PCRs, followed by capillary electrophoresis. A collection of 484 Y. ruckeri isolates, originating from various biological sources and collected from four continents over 7 decades, was analyzed. Minimum-spanning-tree cluster analysis of MLVA profiles separated the studied population into nine major clonal complexes and a number of minor clusters and singletons. The major clonal complexes could be associated with host species, geographic origin, and serotype. A single large clonal complex of serotype O1 isolates dominating the yersiniosis situation in international rainbow trout farming suggests anthropogenic spread of this clone, possibly related to transport of fish. Moreover, subclustering within this clonal complex indicates putative transmission routes and multiple biotype shift events. In contrast to the situation in rainbow trout, Y. ruckeri strains associated with disease in Atlantic salmon appear as more or less geographically isolated clonal complexes. A single complex of serotype O1 exclusive to Norway was found to be responsible for almost all major yersiniosis outbreaks in modern Norwegian salmon farming, and site-specific subclustering further indicates persistent colonization of freshwater farms in Norway. Identification of genetically diverse Y. ruckeri isolates from clinically healthy fish and environmental sources also suggests the widespread existence of less-virulent or avirulent strains.IMPORTANCE This comprehensive population study substantially improves our understanding of the epizootiological history and nature of an internationally important fish-pathogenic bacterium. The MLVA assay developed and presented represents a high-resolution typing tool particularly well suited for Yersinia ruckeri infection tracing, selection of strains for vaccine inclusion, and risk assessment. The ability of the assay to separate isolates into geographically linked and/or possibly host-specific clusters reflects its potential utility for maintenance of national biosecurity. The MLVA is internationally applicable and robust, and it provides clear, unambiguous, and easily interpreted results. Typing is reasonably inexpensive, with a moderate technological requirement, and may be completed from a harvested colony within a single working day. As the resulting MLVA profiles are readily portable, any Y. ruckeri strain may rapidly be placed in a global epizootiological context.

Crystal structure of d-glycero-α-d-manno-heptose-1-phosphate guanylyltransferase from Yersinia pseudotuberculosis.

The Gram-negative bacterium Yersinia pseudotuberculosis is the causative agent of yersiniosis. d-glycero-α-d-manno-heptose-1-phosphate guanylyltransferase (HddC) is the fourth enzyme of the GDP-d-glycero-α-d-manno-heptose biosynthesis pathway which is important for the virulence of the microorganism. Therefore, HddC is a potential target of antibiotics against yersiniosis. In this study, HddC from the synthesized HddC gene of Y. pseudotuberculosis has been expressed, purified, crystallized. Synchrotron X-ray data from a selenomethionine-substituted HddC crystal were also collected and its structure was determined at 2.0Å resolution. Structure analyses revealed that it belongs to the glycosyltransferase A type superfamily members with the signature motif GXGXR for nucleotide binding. Despite of remarkable structural similarity, HddC uses GTP for catalysis instead of CTP and UTP which are used for other major family members, cytidylyltransferase and uridylyltransferase, respectively. We suggest that EXXPLGTGGA and L(S/A/G)X(S/G) motifs are probably essential to bind with GTP and a FSFE motif with substrate.

Low occurrence of pathogenic Yersinia enterocolitica in pig tonsils at slaughter in Southern Brazil.

Yersinia enterocolitica is a foodborne pathogen and pigs are the main reservoir of it in their tonsils. As Brazil is a large producer and exporter of pork meat and information regarding this pathogen is still quite scarce, this study aimed at evaluating the direct detection of Y. enterocolitica followed by pathogenic Y. enterocolitica (PYE) determination in tonsils of slaughtered pigs. For this purpose, 400 pig tonsils were collected from 15 farms in four federally certified slaughterhouses in Southern Brazil. Initially, samples were screened using conventional PCR targeting of the 16sRNA gene, followed by multiplex PCR (mPCR) in order to detect three virulence genes (ail, yadA, and virF) and quantitative real-time PCR (qPCR) for the detection of the ail gene. One hundred and one (25.2%) of the samples tested positive for the 16sRNA gene. However, a PYE was detected in one out of the 101 Y. enterocolitica positive samples. The three virulence genes were determined by mPCR and confirmed by partial DNA sequencing. Thus, a significant occurrence of Y. enterocolitica was observed in pig tonsils from federally inspected slaughterhouses in Brazil, although the presence of pathogenic strains was quite low.

Yersiniosis in Poland in 2015 and 2016

OBJECTIVE: The aim of this study is to assess the epidemiological situation of yersiniosis in Poland in 2015 and 2016 in comparison to the previous years. MATERIAL AND METHODS: The evaluation is based on analysis of data from the annual bulletins "Infectious diseases and poisoning in Poland" (4,5), information from individual yersiniosis case reports sent to the Department of Epidemiology of Infectious Diseases and Surveillance, NIPH-NIH by regional sanitaryepidemiological stations, information on outbreaks delivered by local sanitary-epidemiological stations through the system "Rejestr Ognisk Epidemicznych" (Electronic Registry of Epidemic Outbreaks) and data on deaths from the Department of Demographic Studies of the Central Statistical Office. RESULTS: The number of registered yersiniosis cases in Poland in 2015 and 2016 was the same ­ 205 cases, corresponding to annual incidence of 0.53/100 000. Among them in 2015 there were 172 intestinal yersiniosis cases and 33 extraintestinal yersiniosis cases and in 2016 ­ 167 intestinal yersiniosis cases and 38 extraintestinal yersiniosis cases. In 2015 and 2016 all intestinal yersiniosis cases met the criteria for confirmed case. In turn, among extraintestinal yersiniosis cases in 2015 26 cases met criteria for probable case and 7 for confirmed case and in 2016 ­ 32 for probable and 6 for confirmed case. Both in 2015 and in 2016 the incidence in mazowieckie voivodeship (1.61/100 000 in 2015 and 1.55/100 000 in 2016) largely exceeded the average incidence in Poland. The overall proportion of hospitalizations, 59.5% in 2015 and 58% in 2016, remained at the level similar to the preceding years. Serotype of the isolated Yersinia enterocolitica in 2015 in Poland was determined in 59 cases (32% of all Y. enterocolitica isolates). In 2016 serotype was determined in 47 cases of Y. enterocolitica infections (27% of all Y. enterocolitica isolates). Predominant serotype was O3. As in the previous years about 1/3 of infections occurred among children aged 0-4 (110 cases, 34.9% in 2015 and 92 cases, 30.9% in 2016). In 2015 there were no yersiniosis outbreaks, in 2016 there was one outbreak caused by Y. enterolitica. CONCLUSION: Yersiniosis in Poland is rarely diagnosed and is likely underreported. The percentage of serotyped isolates continues to be low.

Prevalence of Yersinia enterocolitica Bioserotype 3/O:3 among Children with Diarrhea, China, 2010-2015.

Yersinia enterocolitica is thought to not significantly contribute to diarrheal disease in China, but evidence substantiating this claim is limited. We determined the prevalence of Y. enterocolitica infection and strain types present among children <5 years of age with diarrhea in China. The overall prevalence of pathogenic isolates was 0.59%. Prevalence of pathogenic bioserotype 3/O:3 varied geographically. In this population, the presence of fecal leukocytes was a characteristic of Y. enterocolitica infection and should be used as an indication for microbiological diagnostic testing, rather than for the diagnosis of bacillary dysentery. In contrast with Y. enterocolitica isolates from adults, which were primarily biotype 1A, isolates from children were primarily bioserotype 3/O:3. Most pathogenic isolates from children shared pulsed-field gel electrophoresis patterns with isolates from pigs and dogs, suggesting a possible link between isolates from animals and infections in children. Our findings underscore the need for improved diagnostics for this underestimated pathogen.

[Erythema nodosum : a panniculitis of diverse origins]. / L'érythème noueux, une hypodermite aux origines diverses.

Erythema nodosum is an acute nodular panniculitis, mainly affecting young women. Diverse etiologies are evoked, but the most frequent are sarcoidosis (Löfgren syndrome), streptococcal infections, yersiniosis and inflammatory enteropathies. Antalgic drugs and rest are usually adequate in this condition, which is spontaneously of favourable evolution. Treatment of the cause is open to discussion, considering their lack of effect on the evolution of erythema nodosum.

L'érythème noueux est une hypodermite nodulaire aiguë atteignant principalement la femme jeune. Ses racines biologiques sont diverses, mais le tableau étiologique est dominé par la sarcoïdose (syndrome de Löfgren), des infections streptococciques, la yersiniose digestive et des entéropathies inflammatoires. Antalgiques et repos au lit sont habituellement suffisants pour contrôler cette affection d'évolution spontanément favorable. Le traitement de la cause est à discuter en fonction de chaque cas, en sachant qu'il sera sans effet sur l'évolution de l'érythème noueux.

Yersinia enterocolitica Affects Intestinal Barrier Function in the Colon.

Infection with Yersinia enterocolitica causes acute diarrhea in early childhood. A mouse infection model presents new findings on pathological mechanisms in the colon. Symptoms involve diarrhea with watery feces and weight loss that have their functional correlates in decreased transepithelial electrical resistance and increased fluorescein permeability. Y. enterocolitica was present within the murine mucosa of both ileum and colon. Here, the bacterial insult was of focal nature and led to changes in tight junction protein expression and architecture. These findings are in concordance with observations from former cell culture studies and suggest a leak flux mechanism of diarrhea.

Protection of rainbow trout against yersiniosis by lpxD mutant Yersinia ruckeri.

Yersinia ruckeri is a Gram negative bacteria causing yersiniosis in freshwater and marine fish. Lipid A, important for pathogenesis of Gram negative bacteria, biosynthesis pathway requires nine enzyme catalyzed steps. Although there are nine genes encoding lipid A biosynthesis in bacteria, biosynthesis of lipopolysaccharides relies on lpxD gene that encodes the third pathway enzyme. The roles of LpxD in Y. ruckeri virulence have not been studied. In the present study, in-frameshift deletion of lpxD gene and their role in Y. ruckeri virulence in rainbow trout were determined. For this purpose, 92% of the Y. ruckeri lpxD genes were deleted by homologous recombination. After running in SDS-PAGE and staining with silver stain, no LPS was detectable in the Y. ruckeri ΔlpxD mutant. Virulence and immunogenicity of the Y. ruckeri ΔlpxD mutant (YrΔlpxD) were determined in rainbow trout. Rainbow trout immunized with YrΔlpxD with immersion, or intraperitoneal injection method displayed superior protection (relative percentage survival ≥ 84%) after exposure to wild type Y. ruckeri. In conclusion, our results indicated that deletion of the lpxD gene causes significant attenuation of Y. ruckeri in rainbow trout, and LPS deficient YrΔlpxD could be used as a live attenuated vaccine against Y. ruckeri in rainbow trout. This vaccine can protect fish and it can be applied to fish with different methods such as immersion or injection.