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The aim of the present study was to assess the effects of dietary supplementation with Lactobacillus salivarius (LS) ATCC 11741 and lutein (LU) on immunological, antioxidant, and growth responses, and resistance against Yersinia ruckeri infection in rainbow trout (Oncorhynchus mykiss). There were seven experimental diets containing un-supplemented diet (CTL), L. salivarius at 1 × 106 (LS6) and 1 × 108 (LS8) CFU/g, lutein at 50 (LU50) and 150 (LU150) mg/kg, L. salivarius at 1 × 106 CFU/g plus lutein at 50 g/kg (LS6+LU50), and L. salivarius at 1 × 108 CFU/g plus lutein at 150 g/kg (LS8+LU150). These diets were provided to the fish (N= 735; 14.0±0.38 g). After 60 days of feeding, all experimental treatments exhibited significantly higher growth performance, compared to the CTL treatment. The intestinal protease activity and the intestinal lactic acid bacteria population in the probiotic-treated fish were significantly higher than in the CTL fish. The intestinal lipase activity was only higher in the LS6+LU50 treatment, compared to the CTL treatment. Compared to the CTL treatment, the intestinal total bacterial count, and serum superoxide dismutase significantly increased in the LS6+LU50 and LS8+LU150 treatments. The serum catalase significantly increased in LU150, LS6+LU50, and LS8+LU150 treatments, and serum glutathione peroxidase significantly increased in the lutein-treated fish. All experimental treatments, particularly LS6+LU50 and LS8+LU150, had significantly lower serum malondialdehyde levels, compared to the CTL treatment. The levels of serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase in LU50, LS6+LU50, and LS8+LU150 treatments were significantly lower than the CTL. All experimental treatments showed significantly higher serum lysozyme (LYZ), complement, blood respiratory burst activity (RB), and skin mucus alkaline phosphatase (ALP), compared to the CTL treatment. The highest serum LYZ, C4, total immunoglobulin (Ig), blood RB activity, and skin mucus peroxidase, ALP, and Ig were observed in the LS6+LU50 and LS8+LU150 treatments. All the experimental treatments, especially LS6+LU50, exhibited significantly lower mortality after the bacterial challenge compared to the CTL. In conclusion, dietary supplementation with 1 × 106 CFU/g L. salivarius and 50 mg/kg lutein can maximally improve growth performance, digestive enzymes, antioxidant parameters, immune responses, intestinal lactic acid bacteria, and resistance against yersiniosis in rainbow trout. [ABSTRACT FROM AUTHOR]

We report the case of a young woman sough care for disseminated form of Yersinia enterocolitica infection (pseudoappendicitis with mesenteric lymph node, arthralgia, glomerulonephritis and hepatitis) diagnosed on Western Blot method for the detection of Yersinia antibodies. The patient also presented a rare concomitant cutaneous manifestation, as Sweet's syndrome, confirmed histologically. Neutrophilic dermatosis is an exceptional skin features among post-infectious autoimmune disorders when encountering Yersinia enterocolitica infection in clinical practice. [ABSTRACT FROM AUTHOR]

Abstract We report the case of a young woman sough care for disseminated form of Yersinia enterocolitica infection (pseudoappendicitis with mesenteric lymph node, arthralgia, glomerulonephritis and hepatitis) diagnosed on Western Blot method for the detection of Yersinia antibodies. The patient also presented a rare concomitant cutaneous manifestation, as Sweet’s syndrome, confirmed histologically. Neutrophilic dermatosis is an exceptional skin features among post-infectious autoimmune disorders when encountering Yersinia enterocolitica infection in clinical practice.

We described the pathological findings of an abortion associated with Yersinia enterocolitica infection in an ewe. A late-gestation aborted ovine fetus and placenta were submitted for necropsy. Pathologic changes were restricted to the chorioallantois. Grossly, cotyledons and intercodilenary regions had areas of mild red discoloration, and cotyledons were covered with a small amount of fibrin. Histological lesions consisted of multifocal, severe necrotizing and fibrinosuppurative placentitis with fibrinoid vasculitis and mineralization. Bacterial culture of lung, abomasum, and placenta samples yielded pure growth of Y. enterocolitica. This report described the first case of infection by Yersinia enterocolitica causing ovine abortion in Brazil. [ABSTRACT FROM AUTHOR]

Introduction: Three Yersinia species were identified from samples of drinking water from diverse geographic regions of Ireland. Conventional commercial biochemical identification systems classified them as Yersinia enterocolitica. Since this organism is the most common cause of bacterial gastroenteritis in some countries, further investigation was warranted. The aim of the study was to provide a microbial characterisation of three Yersinia species, to determine their pathogenicity, and to review the incidence rate of Yersinia enterocolitica detection in our region. Methods: Organism identification was performed using conventional commercial diagnostic systems MALDI-TOF, API 20E, API 50CHE, TREK Sensititre GNID and Vitek 2 GN, and whole genome sequencing (WGS) was performed. Historical data for detections was extracted from the lab system for 2008 to 2023. Results: All three isolates gave "good" identifications of Yersinia enterocolitica on conventional systems. Further analysis by WGS matched two of the isolates with recently described Yersinia proxima, and the third was a member of the non-pathogenic Yersinia enterocolitica clade 1Aa. Discussion: Our analysis of these three isolates deemed them to be Yersinia species not known currently to be pathogenic, but determining this necessitated the use of next-generation sequencing and advanced bioinformatics. Our work highlights the importance of having this technology available to public laboratories, either locally or in a national reference laboratory. The introduction of molecular technologies for the detection of Yersinia species may increase the rate of detections. Accurate identification of significant pathogens in environmental, public health and clinical microbiology laboratories is critically important for the protection of society. [ABSTRACT FROM AUTHOR]

ABSTRACT: We described the pathological findings of an abortion associated with Yersinia enterocolitica infection in an ewe. A late-gestation aborted ovine fetus and placenta were submitted for necropsy. Pathologic changes were restricted to the chorioallantois. Grossly, cotyledons and intercodilenary regions had areas of mild red discoloration, and cotyledons were covered with a small amount of fibrin. Histological lesions consisted of multifocal, severe necrotizing and fibrinosuppurative placentitis with fibrinoid vasculitis and mineralization. Bacterial culture of lung, abomasum, and placenta samples yielded pure growth of Y. enterocolitica. This report described the first case of infection by Yersinia enterocolitica causing ovine abortion in Brazil.

ABSTRACTThe genus Yersinia includes human, animal, insect, and plant pathogens as well as many symbionts and harmless bacteria. Within this genus are Yersinia enterocolitica and the Yersinia pseudotuberculosis complex, with four human pathogenic species that are highly related at the genomic level including the causative agent of plague, Yersinia pestis. Extensive laboratory, field work, and clinical research have been conducted to understand the underlying pathogenesis and zoonotic transmission of these pathogens. There are presently more than 500 whole genome sequences from which an evolutionary footprint can be developed that details shared and unique virulence properties. Whereas the virulence of Y. pestis now seems in apparent homoeostasis within its flea transmission cycle, substantial evolutionary changes that affect transmission and disease severity continue to ndergo apparent selective pressure within the other Yersiniae that cause intestinal diseases. In this review, we will summarize the present understanding of the virulence and pathogenesis of Yersinia, highlighting shared mechanisms of virulence and the differences that determine the infection niche and disease severity.

Simple Summary: Antibiotics have become a threat to aquaculture due to their negative impact on aquatic environments, fish, and consumers. To contribute to the research and creation of novel tools that are able to treat and control disease in fish and substitute the use of antibiotics in the aquaculture industry, this study investigates the impact of postbiotics added through feed on health parameters and disease resistance in rainbow trout. After 30 days of supplementation with postbiotics, an improvement in survival rate when facing an experimental infection with the causative agent of Red Mouth Disease was observed in rainbow trout. This research illustrates, for the first time, the positive effect of postbiotic supplementation on rainbow trout survival when challenged with Red Mouth Disease infection; in summary, this proves the suitability of the postbiotic product for the aquaculture industry and its relevance regarding the current efforts to reduce and replace the utilization of antibiotics in animal husbandry. Postbiotics are innovative tools in animal husbandry, providing eco-friendly solutions for disease management within the industry. In this study, a new postbiotic product was evaluated for its impact on the health of rainbow trout (Oncorhynchus mykiss). In vivo studies were conducted to assess the safety of the Weissella cibaria strains used in postbiotic production. Additionally, this study evaluated the impact of diet supplementation with 0.50% postbiotics on growth performance during a 30-day feeding trial; the gut microbial communities, immunomodulation, and protection against Yersinia ruckeri infection were evaluated. The strains did not harm the animals during the 20-day observation period. Furthermore, the effect of postbiotics on growth performance was not significant (p < 0.05). The treated group showed a significant increase in acid-lactic bacteria on the 30th day of the feeding trial, with counts of 3.42 ± 0.21 log CFU/mL. Additionally, there was an up-regulation of the pro-inflammatory cytokine IL-1β in head kidney samples after 48 h of feed supplementation, whereas cytokines IL-10, IL-8, INF-γ, and TNF-α were down-regulated. The findings indicate that rainbow trout fed with postbiotics saw an improvement in their survival rate against Y. ruckeri, with a 20.66% survival improvement in the treated group. This study proves that incorporating postbiotics from two strains of W. cibaria previously isolated from rainbow trout into the diet of fish has immunomodulatory effects, enhances intestinal microbial composition, and improves fish resistance against Y. ruckeri. [ABSTRACT FROM AUTHOR]

A 14-year-old female domestic short-haired cat with a diagnosed diabetes mellitus and acromegaly was presented for lethargy and dysorexia. On clinical presentation, the patient showed hyperglycemia, hyperthermia, dull mentation, and dehydration. With the suspicion of an inflammatory or infectious complication of diabetes, she was hospitalized with constant rate infusion of insulin, and empirical ampicillin sulbactam was started. Blood culture revealed positivity for Yersinia pseudotuberculosis and the septic picture was confirmed by blood analysis, with leukocytosis, neutrophilia, and an increased serum amyloid A concentration. The isolated Y. pseudotuberculosis strain showed susceptibility to every antimicrobial tested. During the second day of hospitalization, the onset of hypoglycemia and hypotension was treated with norepinephrine and glucose in fluid therapy. The cat recovered well and was discharged with insulin and amoxicillin-clavulanate. This is the first case of septicemia associated with Y. pseudotuberculosis in a cat, suspected of developing the infection after contact with natural reservoirs such as rodents or birds. This route of transmission should be highlighted especially in relation to the zoonotic potential of the bacteria. [ABSTRACT FROM AUTHOR]

This study analyzed time-dependent effects of vaccination against Y. ruckeri on the oxidative mechanism underlying those effects by detecting relevant lipid peroxidation (2-thiobarbituric acid reactive substances, TBARS) and protein oxidation biomarkers [aldehydic and ketonic derivatives of oxidatively modified proteins (OMP)], antioxidant defenses [activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), total antioxidant capacity (TAC)], as well as activities of lysosomal functioning [alanyl aminopeptidase (AAP), leucyl aminopeptidase (LAP), acid phosphatase (AcP), and â-N-acetylglucosaminidase (NAG)] in hepatic tissue of rainbow trout, Oncorhynchus mykiss (Walbaum) following anti-Y. ruckeri vaccination in the first, second, and sixth months. A concentrated vaccine with Y. ruckeri strains was enclosed in fish feed and was administered three times every other day. Rainbow trout from each group were euthanized 31, 61, and 181 days following vaccination, and hepatic tissue was sampled for analysis. In the current study, vaccination against Y. ruckeri resulted in a no statistically significant change in TBARS levels, while aldehydic and ketonic derivatives of OMP in hepatic tissue decreased, especially after the first and second months following immunization. Moreover, the activities of glutathione-dependent enzymes increased, especially after the first and sixth months. The highest TAC levels were observed two and six months after vaccination. It has been shown that vaccination-related oxidative stress in hepatic tissue is involved in adaptive responses through the temporary mobilization of antioxidant and lysosomal enzymes in rainbow trout. The present study showed the effect of vaccination on lysosome membrane permeability for carbohydrate cleavage after the development of immunity against Yersinia, whereas antioxidant defence was reduced. Our results confirmed that the concept of preserving antioxidant enzyme function after vaccination was also evident when CAT, GR, and GPx activities either increased or were unchanged following vaccination.

A 14-year-old female domestic short-haired cat with a diagnosed diabetes mellitus and acromegaly was presented for lethargy and dysorexia. On clinical presentation, the patient showed hyperglycemia, hyperthermia, dull mentation, and dehydration. With the suspicion of an inflammatory or infectious complication of diabetes, she was hospitalized with constant rate infusion of insulin, and empirical ampicillin sulbactam was started. Blood culture revealed positivity for Yersinia pseudotuberculosis and the septic picture was confirmed by blood analysis, with leukocytosis, neutrophilia, and an increased serum amyloid A concentration. The isolated Y. pseudotuberculosis strain showed susceptibility to every antimicrobial tested. During the second day of hospitalization, the onset of hypoglycemia and hypotension was treated with norepinephrine and glucose in fluid therapy. The cat recovered well and was discharged with insulin and amoxicillin-clavulanate. This is the first case of septicemia associated with Y. pseudotuberculosis in a cat, suspected of developing the infection after contact with natural reservoirs such as rodents or birds. This route of transmission should be highlighted especially in relation to the zoonotic potential of the bacteria.

Objective In this study, we describe the clinical and epidemiological characteristics of a cluster of children with acute gastrointestinal (GI) infection caused by Yersinia enterocolitica in Medellín, Colombia. Methods A retrospective descriptive observational study was performed with the information recorded in clinical charts of GI infection cases caused by Y. enterocolitica in pediatric population of two hospital institutions in Medellín, Colombia. The microorganism identification was performed directly from stool samples using molecular biology techniques and from stool cultures using mass spectrometry. Space-time simulations and antibiotic susceptibility profiles were performed using Whonet 5.6 and Clinical and Laboratory Standards Institute 2020 guide. Results A total of 37 cases were identified in children younger than 15 years; between November 2020 and January 2021, 45.9% of cases were in children aged 1 to 5 years. Most children had diarrhea (97.3%) and fever (67.6%), 21.6% had abdominal pain and vomiting, and 13.5% had hyporexia. Sixteen of the patients (43.2%) received azithromycin, 24.3% (n = 9) received ceftriaxone, and 13.5% (n = 5) received a combined treatment of ceftriaxone and azithromycin or azithromycin and metronidazole. Based on space-time simulations, the clonality analysis and the characteristics of the cases suggest a community outbreak of unknown origin. Conclusion Our findings confirm the occurrence of an outbreak related to Y. enterocolitica from the community whose source could not be identified. Although it is presumed that the frequency of this microorganism is low in these regions, the use of new diagnostic tools in clinical microbiology allowed the early identification of the epidemiological event. [ABSTRACT FROM AUTHOR]

In this study, the immunogenicity of streptococcosis/lactococcosis and yersiniosis vaccine in rainbow trout was investigated in farm. 900 fish with an average of 50±5 g was divided into three treatments and three replications (injection treatment, immersion treatment and control group). Fish were kept for 60 days and samples were taken on the 30th and 60th days. Then the fishes were challenged for 14 days with three bacteria, Streptococcus iniae, Lactococcus garvieae, and Yersinia ruckeri. Sampling was done to evaluate lysozyme activity, complement, antibody titer and survival rate. The results indicated a significant increase in serum complement and lysozyme activity on the 30th and 60th days of sampling in the vaccinated groups compared to the control group (P<0.05). Antibody titers against S. iniae, L. garvieae and Y. ruckeri on the 30th and 60th days of sampling in the vaccinated groups had a significant increase compared to the control group (P < 0.05). The relative percentage survival after 14 days of challenge with S. iniae, L. garvieae and Y. ruckeri in the injected group was (70, 60, and 76.6%), respectively, which was significant compared to the control group (P<0.05). Also, the relative percentage survival in the immersion group with S. iniae, L. garvieae and Y. ruckeri was (30, 36.6 and 53.3%), respectively, which was significant only in the group immersed with S. iniae (P<0.05). In general, it can be concluded that the use of polyvalent vaccine by injection and immersion has significant effects on the immunity and survival rate of rainbow trout. However, the injection method is more effective and suitable than the immersion method. [ABSTRACT FROM AUTHOR]

Diseases are the most significant challenge in the development and stability of aquaculture. In this study, the immunogenic efficiency of polyvalent streptococcosis/lactococcosis and yersiniosis vaccines was evaluated by injection and immersion methods in rainbow trout.. The 450 fish with an average weight of 50 ± 5 g were divided into three treatments and three replications as follows: injection vaccine treatment, immersion vaccine treatment and control group without vaccine administration. Fish were kept for 74 days and sampling was done on days 20, 40 and 60. Then, from the 60th to the 74th day, the immunized groups were challenged with three bacteria Streptococcus iniae (S. iniae), Lactococcus garvieae (L. garvieae) and Yersinia ruckeri (Y. ruckeri) separately. A significant difference was observed in the weight gained (WG) in the immunized groups compared to the control group (P < 0.05). The relative survival percentage (RPS) after 14 days of challenge with S. iniae, L. garvieae and Y. ruckeri in the injection group compared to the control group increased respectively (60%, 60% and 70%), (P < 0.05). Also, RPS in the immersion group had an increase respectively (30%, 40% and 50%) after the challenge with S. iniae, L.garvieae and Y. ruckeri compared to the control group. Immune indicators such as antibody titer, complement and lysozyme activity significantly increased in comparison to the control group (P < 0.05). In general, it can be concluded that applying three vaccines by injection and immersion method has significant effects on immune protection and survival rate. However, the injection method is more effective and more suitable than the immersion method. [ABSTRACT FROM AUTHOR]

The use of antibiotics in aquaculture leads to the proliferation of multidrug-resistant bacteria, and an urgent need for developing new alternatives to prevent and control disease has, thus, arisen. In this scenario, postbiotics represent a promising tool to achieve this purpose; thus, in this study, isolation and selection of bacteria to further produce and evaluate their postbiotics antibacterial activity against fish pathogens was executed. In this respect, bacterial isolates from rainbow trout and Nile tilapia were obtained and tested in vitro against Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida. From 369 obtained isolates, 69 were selected after initial evaluation. Afterwards, additional screening was carried out by spot-on-lawn assay to finally select twelve isolates; four were identified as Pediococcus acidilactici, seven as Weissella cibaria, and one as Weissella paramesenteroides by matrix assisted laser desorption/ionization, time-of-flight mass spectrometry (MALDI-TOF MS). Selected bacteria were used to obtain postbiotic products to test their antagonistic activity through coculture challenge and broth microdilution assays. The influence of incubation time prior to postbiotic production on antagonistic behavior was also recorded. Two isolates identified as W. cibaria were able to significantly reduce (p < 0.05) A. salmonicida subsp. salmonicida's growth in the coculture challenge up to 4.49 ± 0.05 Log CFU/mL, and even though the reduction in Y. ruckeri was not as effective, some inhibition on the pathogen's growth was reported; at the same time, most of the postbiotic products obtained showed more antibacterial activity when obtained from broth cultures incubated for 72 h. Based on the results obtained, the preliminary identification of the isolates that expressed the highest inhibitory activity was confirmed by partial sequencing as W. cibaria. Through our study, it can be concluded that postbiotics produced by these strains are useful to inhibit the growth of the pathogens and could, thereby, be applicable in further research to develop suitable tools as feed additives for disease control and prevention in aquaculture. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We aimed to characterise Yersinia enterocolitica from human clinical specimens in Switzerland using epidemiological, microbiological and whole-genome sequencing (WGS) data. Isolates (n = 149) were collected between January 2019 and December 2023. Epidemiological data was noted and strains were characterized by biochemical and serological typing, antimicrobial susceptibility testing (AST), and WGS-based analysis. Most of the isolates (86%) were from stool specimens and 52% were from male patients. The patients' median age was 28 years (range < 1–94 years). Typing assigned the isolates to bioserotype 4/O:3 (44%), biotype 1A (34%), bioserotype 2/O:9 (21%), and bioserotype 3/O:3 (1%). WGS identified Y. enterocolitica (n = 147), Y. alsatica (n = 1) and Y. proxima (n = 1). Seven isolates were multidrug resistant (MDR) and harboured plasmid pAB829 carrying aph(3″)-Ib, aph(6)-Id, and tet (Y) (n = 1), pAC120 carrying aph(6)-Id and tet (A) (n = 2), or a 12.6 kb Tn 2670 -like transposon containing catA1 , aadA12, sul1, and qacE Δ1 (n = 4). Virulence factors (VFs) included ail (n = 99), invB , (n = 145), ystA (n = 99), ystB (n = 48) and pYV-associated VFs (n = 93). MLST and cgMLST analysis showed that BT 1A strains consisted of several STs and were highly diverse, whereas BT 2/O:9 strains were all ST12 and clustered closely, and BT 4/O:3 strains mostly belonged to ST18 but were more diverse. SNP analysis revealed two highly clonal BT 4/O:3 subpopulations with wide spatio-temporal distribution. Y. enterocolitica BT 1A, BT 2/O:9 and BT 4/O:3 are frequently associated with human yersiniosis in Switzerland. WGS-based subtyping of Y. enterocolitica is a powerful tool to explore the genetic diversity and the pathogenic potential of human isolates. • Whole genome sequencing proved a powerful tool to subtype Yersinia enterocolitica. • Y. enterocolitica BT 1A strains were genetically highly diverse. • Y. enterocolitica BT 2/O:3 strains were all ST12 and clustered closely. • Y. enterocolitica BT 4/O:3 strains mostly belonged to ST18 but were more diverse. • Two highly clonal BT 4/O:3 subpopulations had wide spatio-temporal distribution. [ABSTRACT FROM AUTHOR]

Abstract Yersiniosis is an infectious zoonotic disease caused by two enteropathogenic species of Gram-negative genus Yersinia: Yersinia enterocolitica and Yersinia pseudotuberculosis. Pigs and other wild and domestic animals are reservoirs for these bacteria. Infection is usually spread to humans by ingestion of contaminated food. Yersiniosis is considered a rare disease, but recent studies indicate that it is overlooked in the diagnostic process therefore the infections with this bacterium are not often identified. Reliable diagnosis of Yersiniosis by culturing is difficult due to the slow growth of the bacteria easily overgrown by other more rapidly growing microbes unless selec-tive growth media is used. Phage adhesins recognizing bacteria in a specific manner can be an excellent diagnostic tool, es-pecially in the diagnosis of pathogens difficult for culturing. In this study, it was shown that Gp17, the tail fiber protein (TFP) of phage φYeO3-12, specifically recognizes only the pathogenic Yersinia enterocolitica serotype O:3 (YeO:3) bacteria. The ELISA test used in this work confirmed the specific interaction of this protein with YeO:3 and demonstrated a promising tool for developing the pathogen recognition method based on phage adhesins.

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Yersinia enterocolitica is a Gram-negative bacterium that typical results in enterocolitis in humans and poses significant worldwide risks to public health. An outbreak of yersiniosis in the Vervet/African green monkey colony at the WFSM during the winter of 2015–2016 accounted for widespread systemic infection with high morbidity and mortality. Most of the cases had extensive necrosis with suppuration and large colonies of bacilli in the large bowel and associated lymph nodes; however, the small intestine, stomach, and other organs were also regularly affected. Positive cultures of Yersinia enterocolitica were recovered from affected tissues in 20 of the 23 cases. Carrier animals in the colony were suspected as the source of the infection because many clinically normal animals were culture-positive during and after the outbreak. In this study, we describe the gross and histology findings and immune cell profiles in different organs of affected animals. We found increased numbers of myeloid-derived phagocytes and CD11C-positive antigen-presenting cells and fewer adaptive T and B lymphocytes, suggesting an immunocompromised state in these animals. The pathogen-mediated microenvironment may have contributed to the immunosuppression and rapid spread of the infection in the vervets. Further studies in vervets could provide a better understanding of Yersinia-mediated pathogenesis and immunosuppression, which could be fundamental to understanding chronic and systemic inflammatory diseases in humans.

Yersiniosis is one of the most important bacterial diseases that cause a lot of economic losses to cold-water fish farms in the country. Therefore, the use of effective vaccination is one of the best ways to control this disease. In this study, the vaccine efficacy of different methods of bathing in these fish has been evaluated. In this regard, 300 fish with an average weight of 3 ± 0.35 were divided into 12 tanks after adaptation. In this study, 6 experimental groups including a positive control group, negative control group, single dose vaccinated fish group, two-dose vaccinated fish group, hyperosmotic environment + single dose vaccinated fish group, and hyperosmotic environment + two-dose vaccinated fish group. Fish from different groups were exposed to 4.3 10 107 bacteria intraperitoneally after vaccination and the survival rates of the fish was evaluated. Based on the results, the white blood cells counts (WBC) in the vaccinated groups were significantly higher than the control group. Yersinia ruckeri antibody titers by microagglutination method were also measured significantly higher in the vaccinated groups compare to the control, in the other hand, in the fish that received the vaccine twice, this titer was significantly higher than the other groups. According to the bacterial exposure results, 100% of the fish in the control group died during 5 days. In all vaccinated groups, the mortality rate was significantly lower than the control group, while the lowest mortality rate was recorded for fish in the hyperosmotic environment + twice vaccine. In this study, vaccination significantly reduced fish mortality after exposure to Yersinia rockeri bacterium, and based on this study, the use of hyperosmotic environments with vaccination is recommended to increase vaccine efficacy. [ABSTRACT FROM AUTHOR]

The aim of the work was to rank statistical models for assessing the contribution of a number of factors that determine the epizootic situation on natural-focal infectious diseases in the communities of non-synanthropic small mammals (SM) in the forests of Ekaterinburg.Materials and methods. The SM survey was carried out for three years in the summer-autumn period. The animals were caught with snap tpaps on a standard bread bait, 9705 trap-nights were worked out. To identify infections (hemorrhagic fever with renal syndrome, tularemia, leptospirosis, yersiniosis, pseudotuberculosis), 333 SM specimens (rodents and shrews of six species) were used, randomly taken from the general sample. To determine the pathogens, the methods of enzyme immunoassay and polymerase chain reaction were used. The cumulative infection rate of small mammals with all studied natural-focal infections was evaluated. Statistical data processing was carried out from the standpoint of a multi-model approach. The selection of models was performed using the Akaike information criterion with the calculation of the sum of the weights of the models based on their full spectrum (SW).Results and discussion. Carriers of all of the mentioned above infections, except for pseudotuberculosis, have been identified in the forest parks of Ekaterinburg. According to the ranking, the model with three predictors received the highest weight: species, year, and the abundance of SM of the previous year in a particular habitat. The most significant predictors for the full spectrum of models are the year (SW=1), species (SW=0.6), abundance of animals in the current and previous year (SW=0.48). The distribution of positive samples by species of small mammals corresponded to their ranking by abundance in the community. The influence of the factors “season” (summer or autumn) and “area” (place of capture of animals) turned out to be insignificant on the scale of the studies (SW = 0.3 and 0.16, respectively). The percentage of infected samples in total for all infections varied significantly by location and year (0–60%). The possible significance of unaccounted factors is discussed: landscape features and the mode of using forest parks, dispersal of small mammals. The conclusion is made about the usefulness of the multi-model approach in the analysis of the data from epizootiological studies.

To date, Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis are the three Yersinia species generally agreed to be pathogenic in humans. However, there are a limited number of studies that suggest some of the “non-pathogenic” Yersinia species may also cause infections. For instance, Yersinia frederiksenii used to be known as an atypical Y. enterocolitica strain until rhamnose biochemical testing was found to distinguish between these two species in the 1980s. From our regional microbiology laboratory records of 18 hospitals in Eastern Ontario, Canada from 1 May 2018 to 1 May 2021, we identified two patients with Y. frederiksenii isolates in their stool cultures, along with their clinical presentation and antimicrobial management. Both patients presented with diarrhea, abdominal pain, and vomiting for 5 days before presentation to hospital. One patient received a 10-day course of sulfamethoxazole-trimethoprim; his Y. frederiksenii isolate was shown to be susceptible to amoxicillin-clavulanate, ceftriaxone, ciprofloxacin, and sulfamethoxazole-trimethoprim, but resistant to ampicillin. The other patient was sent home from the emergency department and did not require antimicrobials and additional medical attention. This case series illustrated that diarrheal disease could be associated with Y. frederiksenii; the need for antimicrobial treatment should be determined on a case-by-case basis.

[Display omitted] • Developed a new potent vaccine against the Yersinia enterocolitica by employing in silico techniques. • The accurate quantitative assessment of the epitopes was applied to ensure the immunogenicity and safety of vaccine • Epitope stability and interaction affinity with human immune receptors were predicted using molecular docking and dynamics simulations. • Highlighted the clinical potential, paving the way for experimental validation and future development of vaccines against Yersinia enterocolitica. Yersinia enterocolitica , a foodborne pathogen, has emerged as a significant public health concern due to its increased prevalence and multidrug resistance. This study employed reverse vaccinology to identify novel vaccine candidates against Y. enterocolitica through comprehensive in silico analyses. The core genome's conserved protein translocase subunit SecY was selected as the target, and potential B-cell, MHC class I, and MHC class II epitopes were mapped. 3B-cell epitopes, 3 MHCI and 11 MHCII epitopes were acquired. A multi-epitope vaccine construct was designed by incorporating the identified epitopes, TLR4 Agonist was used as adjuvants to enhance the immunogenic response. EAAAK, CPGPG and AYY linkers were used to form a vaccine construct, followed by extensive computational evaluations. The vaccine exhibited desirable physicochemical properties, stable secondary and tertiary structures as evaluated by PDBSum and trRosetta. Moreover, favorable interactions with the human Toll-like receptor 4 (TLR4) was observed by ClusPro. Population coverage analysis estimated the vaccine's applicability across 99.74 % in diverse populations. In addition, molecular dynamics simulations and normal mode analysis confirmed the vaccine's structural stability and dynamics in a simulated biological environment. Furthermore, codon optimization and in silico cloning facilitated the evaluation of the vaccine's expression potential in E. coli and pET-28a was used a recombinant plasmid. This study provides a promising foundation for the development of an efficacious vaccine against Y. enterocolitica infections. [ABSTRACT FROM AUTHOR]

ABSTRACT Yersinia enterocolitica is a bacterium with zoonotic potential and there are no previous records of this bacteria being isolated from aborted foals. This report aims to describe a case of sepsis due to Y. enterocolitica in a seven month old aborted equine. The fequinoetus was submitted to necropsy and samples of all the organs were collected for the histological exam. Samples of liver, lung, placenta, and stomach contents were collected for bacterial culture. Macroscopically, the liver was enlarged with yellowish heterogeneous color, heart with pale myocardial areas; lungs not collapsed, heavy and shiny, thickened umbilical cord covered with fibrin and pus. Histopathologically, there was moderate multifocal necrosuppurative myocarditis and thrombosis, moderate diffuse suppurative bronchopneumonia, mild multifocal fibrinonecrotic hepatitis, and moderate diffuse necrosuppurative omphalitis with intralesional bacterial myriads and thrombosis. Mild multifocal suppurative placentitis, nephritis, myositis, cystitis, and dermatitis were also observed, in addition to mild diffuse lymphoid rarefaction. The microbiological evaluation identified Y. enterocolitica in the liver, lung, and stomach fluid. This is the first report of sepsis due to Y. enterocolitica causing an abortion in a horse. This bacterium has zoonotic importance; therefore, it should be investigated in abortion in this species, serving as a differential diagnosis in reproductive disorders.

The articular syndrome, although it requires, first of all, the exclusion of systemic diseases of the connective tissue, contrary to the common stereotype, is rather nonspecific. It can also be accompanied by infectious pathology, the incidence of various variants of which is quite high. On an outpatient basis, doctors of any specialty are faced with yersiniosis, the clinical manifestations of which are polymorphic and similar to those of other diseases. Below is an example of the course of yersiniosis with a predominance of articular syndrome in the clinical picture.

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. [ABSTRACT FROM AUTHOR]

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-1β, 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. [ABSTRACT FROM AUTHOR]

A concurrent outbreak of infection with Yersinia pseudotuberculosis occurred in adult captive African lions (Panthera leo). Two 17-y-old male lions and one 14-y-old female lion developed respiratory distress, lethargy, ataxia, and hyporexia. Within 3–5 d of the onset of clinical signs, one male and the female lion died and were submitted for postmortem examination. Macroscopically, the liver and spleen had multifocal-to-coalescing, semi-firm, pale-tan nodules throughout the parenchyma. The lungs were non-collapsed and marked by petechiae. Histologic examination identified lytic, necrosuppurative foci in the liver, spleen, lungs, and kidney, with abundant intralesional gram-negative coccobacilli in the male lion. Similar findings were seen in the female lion in the liver, spleen, kidney, and mesenteric lymph node; however, the intralesional bacterial colonies were more pleomorphic, comprising rod and filamentous morphologies. Aerobic bacterial culture of the liver, spleen, and lung revealed Y. pseudotuberculosis growth. The source of infection is unknown, and an epidemiologic study was performed. Sources to be considered are from the predation of rodent and/or bird reservoirs, or contaminated soil or water. Mortality associated with Y. pseudotuberculosis has been described in an African lion cub, however, to our knowledge, Y. pseudotuberculosis has not been reported in adult African lions, and this is only the second report of Y. pseudotuberculosis with aberrant bacterial morphology observed histologically. [ABSTRACT FROM AUTHOR]

The genus Yersinia includes human, animal, insect, and plant pathogens as well as many symbionts and harmless bacteria. Within this genus are Yersinia enterocolitica and the Yersinia pseudotuberculosis complex, with four human pathogenic species that are highly related at the genomic level including the causative agent of plague, Yersinia pestis . Extensive laboratory, field work, and clinical research have been conducted to understand the underlying pathogenesis and zoonotic transmission of these pathogens. There are presently more than 500 whole genome sequences from which an evolutionary footprint can be developed that details shared and unique virulence properties. Whereas the virulence of Y. pestis now seems in apparent homoeostasis within its flea transmission cycle, substantial evolutionary changes that affect transmission and disease severity continue to ndergo apparent selective pressure within the other Yersiniae that cause intestinal diseases. In this review, we will summarize the present understanding of the virulence and pathogenesis of Yersinia , highlighting shared mechanisms of virulence and the differences that determine the infection niche and disease severity.

Yersiniosis is an infectious zoonotic disease caused by two enteropathogenic species of Gram-negative genus Yersinia: Yersinia enterocolitica and Yersinia pseudotuberculosis. Pigs and other wild and domestic animals are reservoirs for these bacteria. Infection is usually spread to humans by ingestion of contaminated food. Yersiniosis is considered a rare disease, but recent studies indicate that it is overlooked in the diagnostic process therefore the infections with this bacterium are not often identified. Reliable diagnosis of Yersiniosis by culturing is difficult due to the slow growth of the bacteria easily overgrown by other more rapidly growing microbes unless selec-tive growth media is used. Phage adhesins recognizing bacteria in a specific manner can be an excellent diagnostic tool, es-pecially in the diagnosis of pathogens difficult for culturing. In this study, it was shown that Gp17, the tail fiber protein (TFP) of phage φYeO3-12, specifically recognizes only the pathogenic Yersinia enterocolitica serotype O:3 (YeO:3) bacteria. The ELISA test used in this work confirmed the specific interaction of this protein with YeO:3 and demonstrated a promising tool for developing the pathogen recognition method based on phage adhesins. [ABSTRACT FROM AUTHOR]

Yersinia infections are recorded worldwide and sapronotic natural foci of Yersinia enterocolitica and Y. pseudotuberculosis infections also occur in the Crimean Peninsula. Here we studied the distribution and prevalence of pathogenic Yersiniae among small mammals of the Crimean Peninsula based on results of epizootiological monitoring of natural foci infections. Pathogenic Y. enterocolitica were found in 10 species of small mammals, and the average number of infected specimens in the Crimea was 0.11 ± 0.03. The highest prevalence of yersiniosis pathogens was recorded among specimens of M. socialis (4.22 %), M. spicilegus (2.06 %), C. leucodon (1.96 %), S. flavicollis (1.85 %), and S. uralensis (1.33 %). The number of small mammals that are carriers of pathogens of yersinioses varies significantly in different natural zones of the Crimean Peninsula. In the mountain-forest zone, the prevalence of Y. enterocolitica among Micromammalia is 2.94 %, in the foothills it decreases to 0.99 %, in the lowland — to 0.77 % with a lowest value of 0.62 % in steppe areas of the Kerch Peninsula. Results show a decreasing pattern of prevalence of Y. enterocolitica among small mammals from the mountain-forest zone to plain steppe. A reverse trend was revealed for the prevalence of Y. pseudo­tuberculosis among Micromammalia: 0.03 % in the mountains, 0.17 % in the foothills, and 0.25 % in the steppe. The number of trap-lines with records of Micromammalia having both infections varies from 18.3 % in the foothills to 21.3 % in the mountains and 24.8 % in the steppe zone. The portion of trap-lines with three and more infections is also high (6.7 % in the mountains and foothills and 5.5 % in the steppe). The obtained results show a wide distribution of combined foci in the Crimea. Considering that, in the peninsula, several tick-transmitted and other zoonotic infections (e.g. tick-borne encephalitis and borrelioses, anaplasmosis, ehrlichiosis, Marseilles fever, Q fever, etc.) are widely distributed in the same areas and the pathogens of which are able to reproduce in the same small mammal species as those of yersiniosis and pseudotuberculosis, the real number of combined foci and their diversity in the Crimea could be 3 to 5 times higher.

Characteristics of the clinical process and immunological profile in children with yersiniosis as a monoinfection or in association with acute intenstinal infections and virus hepatitis A are presented. The efficacy of the immunotropic therapy with cycloferon, an interferon inductor, and recombinant interferon in the patients with the viral and bacterial association of the disease (yersiniosis + hepatitis A) and initial disbalance of the serum cytokines was estimated. Dependence of the interferon clinicolaboratory efficacy on the initial levels of serum γ-interferon, IL2 and IL4, promoting shorter terms of hyperthermia, diarrhea syndrome and cytolysis syndrome was shown. It allowed to optimize the scheme of the pathogenetic therapy of Yersinia mixed infection.

The efficacy of cycloferon in complex therapy of salmonellosis and yersiniosis in children (n=220) was investigated under clinical and laboratory conditious. It was shown, that cycloferon had direct and indirect immunotropic action in salmonellosis and yersiniosis in children. In contrast to the conventional antibiotic therapy, the use of cycloferon provided a more rapid relief of the local and systemic symptoms, reduction of superinfection or exacerbation. It had a positive effect on the antiinfective resistance of the colon mucosa resulting in normalization of the colon lumen microecology. The use of cycloferon provided eradication of the pathogen and opportunistic organisms. In the treatment of salmonellosis it enhanced formation of rare bacterial reconvalescent Shigella.

The use of antibiotics in aquaculture leads to the proliferation of multidrug-resistant bacteria, and an urgent need for developing new alternatives to prevent and control disease has, thus, arisen. In this scenario, postbiotics represent a promising tool to achieve this purpose; thus, in this study, isolation and selection of bacteria to further produce and evaluate their postbiotics antibacterial activity against fish pathogens was executed. In this respect, bacterial isolates from rainbow trout and Nile tilapia were obtained and tested in vitro against Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida. From 369 obtained isolates, 69 were selected after initial evaluation. Afterwards, additional screening was carried out by spot-on-lawn assay to finally select twelve isolates; four were identified as Pediococcus acidilactici, seven as Weissella cibaria, and one as Weissella paramesenteroides by matrix assisted laser desorption/ionization, time-of-flight mass spectrometry (MALDI-TOF MS). Selected bacteria were used to obtain postbiotic products to test their antagonistic activity through coculture challenge and broth microdilution assays. The influence of incubation time prior to postbiotic production on antagonistic behavior was also recorded. Two isolates identified as W. cibaria were able to significantly reduce (p < 0.05) A. salmonicida subsp. salmonicida’s growth in the coculture challenge up to 4.49 ± 0.05 Log CFU/mL, and even though the reduction in Y. ruckeri was not as effective, some inhibition on the pathogen’s growth was reported; at the same time, most of the postbiotic products obtained showed more antibacterial activity when obtained from broth cultures incubated for 72 h. Based on the results obtained, the preliminary identification of the isolates that expressed the highest inhibitory activity was confirmed by partial sequencing as W. cibaria. Through our study, it can be concluded that postbiotics produced by these strains are useful to inhibit the growth of the pathogens and could, thereby, be applicable in further research to develop suitable tools as feed additives for disease control and prevention in aquaculture.

Yersiniosis, caused by Yersinia ruckeri, has become the most common disease in farmed rainbow trout Oncorhynchus mykiss in Peru, affecting Puno and Junín Regions, important aquaculture areas in the country. Florfenicol (FLO) and oxytetracycline (OXY) are the antimicrobials most frequently used to mitigate losses attributed to this pathogen. This study presents an analysis of the susceptibility patterns of 60 Y. ruckeri isolates (30 isolates each from Puno and Junín), including the type strain CECT 4319T and the strains CECT 955 and CECT 956, against FLO and OXY. Minimum inhibitory concentrations (MICs) were determined following the guideline for standard broth dilution method published by the Clinical and Laboratory Standards Institute. MIC results ranged from 4.0 to 8.0 µg ml-1 for FLO and 0.5 to 4.0 µg ml-1 for OXY. Normalized resistance interpretation (NRI) analysis identified epidemiological cut-off values of ≤16.0 µg ml-1 for FLO and ≤4.0 µg ml-1 for OXY. All Peruvian isolates, including the collection strains, were categorized as wild-type for both antimicrobials. Even though the number of Y. ruckeri isolates with MIC values of 8 µg ml-1 for FLO is more than double in Puno than in Junín (15 vs. 7 isolates), the NRI analysis showed the same epidemiological cutoff of 16 µg ml-1; while for OXY, it was 4.0 µg ml-1 for Puno and 2.0 µg ml-1 for Junín. This study establishes the basis for monitoring susceptibility to FLO and OXY in new Y. ruckeri isolates in Peruvian rainbow trout farming.

Abstract: In January 2023, an outbreak of Yersinia enterocolitica in residential aged care facilities (RACF) was identified by the Gold Coast Public Health Unit and confirmed using whole genome sequencing. During the outbreak period there were 11 confirmed and 14 probable cases of Y. enterocolitica notified in RACF and 30 suspected cases with compatible illness. Eleven cases (20%) were confirmed as Biotype 1A non-typable (BT1A NT) sequence type (ST) 278 within 4-15 single nucleotide polymorphisms (SNP) of each other. Combined epidemiological, trace-back and laboratory investigations identified nutritional milkshakes, stored at ideal growing conditions for Yersinia and given to vulnerable RACF residents, as the likely outbreak vehicle. This highlights that Y. enterocolitica Biotype 1A can be pathogenic in humans and transmission via atypical sources should be considered in outbreak investigations. This report outlines the response and challenges associated with investigating outbreaks in aged care., (© Commonwealth of Australia CC BY-NC-ND.)

Yersinia enterocolitica ( Y. enterocolitica ) is the most frequent etiological agent of yersiniosis and has been responsible for several national outbreaks in Norway and elsewhere. A standardized high-resolution method, such as core genome Multilocus Sequence Typing (cgMLST), is needed for pathogen traceability at the national and international levels. In this study, we developed and implemented a cgMLST scheme for Y. enterocolitica . We designed a cgMLST scheme in SeqSphere + using high-quality genomes from different Y. enterocolitica biotype sublineages. The scheme was validated if more than 95% of targets were found across all tested Y. enterocolitica : 563 Norwegian genomes collected between 2012 and 2022 and 327 genomes from public data sets. We applied the scheme to known outbreaks to establish a threshold for identifying major complex types (CTs) based on the number of allelic differences. The final cgMLST scheme included 2,582 genes with a median of 97.9% (interquartile range 97.6%-98.8%) targets found across all tested genomes. Analysis of outbreaks identified all outbreak strains using single linkage clustering at four allelic differences. This threshold identified 311 unique CTs in Norway, of which CT18, CT12, and CT5 were identified as the most frequently associated with outbreaks. The cgMLST scheme showed a very good performance in typing Y. enterocolitica using diverse data sources and was able to identify outbreak clusters. We recommend the implementation of this scheme nationally and internationally to facilitate Y. enterocolitica surveillance and improve outbreak response in national and cross-border outbreaks., Competing Interests: The authors declare no conflict of interest.

Upward trend in the number of human yersiniosis cases, caused by bacterium Yersinia enterocolitica, is globally observed nowadays. This microorganism is widely spread in the environment, able to persist for prolonged periods in animal products and propagate under low temperatures. Basic infection sources are meat and meat products. In order to isolate Yersinia enterocolitica from food and feed samples horizontal method for the detection pursuant to GOST ISO 10273-2013 was used. It was noted, that Yersinia enterocolitica isolation is associated with certain difficulties, because the sample contains only small quantities of the agent and only the use of special techniques allows removing the concurrent microflora. It was proposed to use cold enrich­ment (4 ± 1) °C of the test material before conventional technique is started. The technique was validated pursuant to GOST ISO 16140-2011. As a result, it was established that validated method for Yersinia enterocolitica bacteria detection in food products, performed at the Microbiology Laboratory, is specific. The method sensitivity is 10 CFU/cm3. Intralaboratory reproducibility and repeatability were confirmed by relevant tests. Additional culture step at (4 ± 1) °C allows complete inhibition of non-psychrophilic microorganisms’ growth.

The present study investigated the susceptibility of Caspian roach, Rutilus caspicus to experimental exposure of Yersinia ruckeri. In this regard, 144 Caspian roach fingerlings with average weight of 9.3 ± 2.1 were assigned to 12 aquaria (12 fish per aquarium). Fish were acclimated for 4 weeks before challenge. Five experimental treatments and one control group (each with two replicates) were considered. After preparation of bacterial suspension, fish were challenged via intra peritoneal injection with different dosages of bacteria including 5.4×108, 5.4×107, 5.4 ×106, 5.4 ×105 and 5.4 ×104 cells/fish. Fish in control group received sterile normal saline. After 21 days, the median lethal concentration (LC50) of this bacterium calculated as 4.4×107. The most gill histopathology signs in sick fish included epithelial lifting and inflammatory cell infiltration in secondary lamella and hyperplasia in base of secondary lamella. Kidney histopathology was characterized by congestion in vessels and interstitial tissue, focal necrosis and inflammatory cell infiltration. In liver tissue, vacuolization of hepatocytes was observed in most specimens and focal hepatocyte necrosis was recorded in some individuals.

The article describes two clinical cases of yersiniosis accompanied by Hepatitis A and E. In patients with a clinical picture of icteric form of acute viral hepatitis, there was a symptomatic gastrointestinal form of yersiniosis. Patients were discharged on day 22,5±3,5 of the disease with moderate cytolysis. In the enzyme immunoassay at the time of discharge IgM and IgG were detected to Y. Enterocolitica, indicating a tendency in the progradient case of yersiniosis.

To date, Yersinia pestis, Yersinia enterocolitica, and Yersinia pseudotuberculosis are the three Yersinia species generally agreed to be pathogenic in humans. However, there are a limited number of studies that suggest some of the “non-pathogenic” Yersinia species may also cause infections. For instance, Yersinia frederiksenii used to be known as an atypical Y. enterocolitica strain until rhamnose biochemical testing was found to distinguish between these two species in the 1980s. From our regional microbiology laboratory records of 18 hospitals in Eastern Ontario, Canada from 1 May 2018 to 1 May 2021, we identified two patients with Y. frederiksenii isolates in their stool cultures, along with their clinical presentation and antimicrobial management. Both patients presented with diarrhea, abdominal pain, and vomiting for 5 days before presentation to hospital. One patient received a 10-day course of sulfamethoxazole-trimethoprim; his Y. frederiksenii isolate was shown to be susceptible to amoxicillin-clavulanate, ceftriaxone, ciprofloxacin, and sulfamethoxazoletrimethoprim, but resistant to ampicillin. The other patient was sent home from the emergency department and did not require antimicrobials and additional medical attention. This case series illustrated that diarrheal disease could be associated with Y. frederiksenii; the need for antimicrobial treatment should be determined on a case-by-case basis. [ABSTRACT FROM AUTHOR]

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-1β, 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.

BACKGROUND: Yersiniosis is known as one of the most prevalent bacterial diseases in fish, which causes high mortality and economic losses in cultured fish farms every year. OBJECTIVES: The present study was conducted to investigate the changes in hematological indices and gut histopathology in Caspian roach (Rutilus caspicus) exposed to Yersinia ruckeri. METHODS: 60 Caspian roach broodstock with an average weight of 63.4 ± 2.1 g were divided into three groups (with two replicates for each group), including one treatment, one positive control, and one negative control groups. The treatment group was intraperitoneally injected with Yersinia ruckeri bacterium at a dosage of 3.8 × 107 cell/fish. The positive group just received normal saline (0.9 % NaCl) via intraperitoneal injection. No injection was performed in the negative control group. RESULTS: Symptoms appeared on the fourth day after exposure and 20 % of the fish in the treatment group died 5 days after the challenge. Cumulative mortality reached 53 % on day 9 after the challenge. According to hematological analysis, the challenge with Yersinia ruckeri led to a significant increase in white blood cell counts (WBC) compared to the control groups. Moreover, 10 days following exposure, the treatment group experienced hypochromic macrocytic anemia. Gut histopathology was characterized with necrosis and detachment of intestinal epithelial cell and inflammatory cells infiltration in the treatment group. CONCLUSIONS: Based on the obtained results herein, Yersinia rackeri can cause acute disease in Caspian roach; therefore, preventing and controlling this disease is essential for these fish in infected regions. [ABSTRACT FROM AUTHOR]

The salmonids represent a valuable food source for humans, thanks to a high nutritional value and digestibility. In recent times, the authorities are preoccupied with insuring the health and wellbeing of the consumers, by obtaining high quality, healthy and safe aquaculture products. The aim of this paper is health status monitoring for rainbow trout (Oncorhynchus mykiss), during the disease caused by Yersinia rukeri, quantified through the biochemical composition of the meat. Yersiniosis is a illness that leads to significant economical losses in aquaculture industry. The biological material – rainbow trout Oncorhynchus mykiss – was monitored monthly for 7 months. The biochemical analysis of trout meat was realized at the moment of identification of pathogenic bacterium Yersinia rukeri through microbiological methods, after 15 days following a 10 day treatment with antibiotics. The experiment demonstrated that the disease state compromises growth performance and nutritional value of the infected biological material. However, the results indicated that after a 15 day period following the treatment, the maintenance status of rainbow trout will get better, without recovering the weight loss determined by the disease. [ABSTRACT FROM AUTHOR]

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To counteract the deadly pathogens, i.e., Y. pestis, Y. enetrocolitica, and Y. pseudotuberculosis, we prepared a recombinant DNA construct lcrV-hsp70 encoding the bivalent fusion protein LcrV-HSP70. The lcrV gene of Y. pestis and hsp70 domain II DNA fragment of M. tuberculosis were amplified by PCR. The lcrV amplicon was first ligated in the pET vector using NcoI and BamHI restriction sites. Just downstream to the lcrV gene, the hsp70 domain II was ligated using BamHI and Hind III restriction sites. The in-frame and the orientation of cloned lcrV-hsp70 were checked by restriction analysis and nucleotide sequencing. The recombinant bivalent fusion protein LcrV-HSP70 was expressed in E. coli and purified by affinity chromatography. The vaccine potential of LcrV-HSP70 fusion protein was evaluated in formulation with alum. BALB/c mice were vaccinated, and the humoral and cellular immune responses were studied. The fusion protein LcrV-HSP70 induced a strong and significant humoral immune response in comparison to control animals. We also observed a significant difference in the expression levels of IFN-γ and TNF-α in LcrV–HSP70-immunized mice in comparison to control, HSP70, and LcrV groups. To test the protective efficacy of the LcrV–HSP70 fusion protein against plague and Yersiniosis, the vaccinated mice were challenged with Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis separately. The bivalent fusion protein LcrV–HSP70 imparted 100% protection against the plague. In the case of Yersiniosis, on day 2 post challenge, there was a significant reduction in the number of CFU of Y. enterocolitica and Y. pseudotuberculosis in the blood (CFU/ml) and the spleen (CFU/g) of vaccinated animals in comparison to the LcrV, HSP70, and control group animals.

This study aims to analyse the effect of complementing the rations of breeding rainbow trout with different concentrations levels of celmanax® prebiotic, which contains Saccharomyces cerevisia associated compounds with Mannan-oligosaccharide on the growth indexes and histologic effects of the prebiotic and the gastrointestinal tract and also measuring of the resistance of breeding fishes fed with this prebiotic in infection to the yersiniosis. Three concentration levels of prebiotic (0, 0.1, 0.5 and 1 %) were mixed into pellets. The fish (19.08±1.45gr) were fed a supplemented commercial diet for 60 days in four treatments and each treatment with three replications. Also, on day 60 of study, the Yersinia ruckeri bacterium was injected empirically into all of our groups. This study’s results showed that complementing rainbow trout rations with different concentrations level of celmanax® (P

Macrophages participate to the first line of defense against infectious agents. Microbial pathogens evolved sophisticated mechanisms to escape macrophage killing. Here, we review recent discoveries and emerging concepts on bacterial molecular strategies to subvert macrophage immune responses. We focus on the expanding number of fascinating subversive tools developed by Listeria monocytogenes, Staphylococcus aureus , and pathogenic Yersinia spp., illustrating diversity and commonality in mechanisms used by microorganisms with different pathogenic lifestyles. [ABSTRACT FROM AUTHOR]