Yersinia ruckeri Infection and Enteric Redmouth Disease among Endangered Chinese Sturgeons, China, 2022.

During October 2022, enteric redmouth disease (ERM) affected Chinese sturgeons at a farm in Hubei, China, causing mass mortality. Affected fish exhibited characteristic red mouth and intestinal inflammation. Investigation led to isolation of a prominent bacterial strain, zhx1, from the internal organs and intestines of affected fish. Artificial infection experiments confirmed the role of zhx1 as the pathogen responsible for the deaths. The primary pathologic manifestations consisted of degeneration, necrosis, and inflammatory reactions, resulting in multiple organ dysfunction and death. Whole-genome sequencing of the bacteria identified zhx1 as Yersinia ruckeri, which possesses 135 drug-resistance genes and 443 virulence factor-related genes. Drug-susceptibility testing of zhx1 demonstrated high sensitivity to chloramphenicol and florfenicol but varying degrees of resistance to 18 other antimicrobial drugs. Identifying the pathogenic bacteria associated with ERM in Chinese sturgeons establishes a theoretical foundation for the effective prevention and control of this disease.

Innate and adaptive immune response of Rainbow trout (Oncorhynchus mykiss) naturally infected with Yersinia ruckeri.

Rainbow trout is an important fish species for Peruvian artisanal aquaculture, comprising over 60 % of the total aquaculture production. However, their industry has been highly affected by several bacterial agents such as Yersinia ruckeri. This pathogen is the causative agent of Enteric Redmouth Disease, and causes high mortality in fingerlings and chronic infection in adult rainbow trout. To date, the immune response of rainbow trout against Y. ruckeri has been well studied in laboratory-controlled infection studies (i.e. intraperitoneal infection, bath immersion), however, the immune response during natural infection has not been explored. To address this, in this study, 35 clinically healthy O. mykiss without evidence of lesions or changes in behavior and 32 rainbow trout naturally infected by Y. ruckeri, were collected from semi-intensive fish farms located in the Central Highlands of Peru. To evaluate the effect on the immune response, RT-qPCR, western blotting, and ELISA were conducted using head kidney, spleen, and skin tissues to evaluate the relative gene expression and protein levels. Our results show a significant increase in the expression of the pro-inflammatory cytokines il1b, tnfa, and il6, as well as ifng in all three tissues, as well as increases in IL-1ß and IFN-γ protein levels. The endogenous pathway of antigen presentation showed to play a key role in defense against Y. ruckeri, due to the upregulation of mhc-I, tapasin, and b2m transcripts, and the significant increase of Tapasin protein levels in infected rainbow trout. None of the genes associated with the exogenous pathway of antigen presentation showed a significant increase in infected fish, suggesting that this pathway is not involved in the response against this intracellular pathogen. Finally, the transcripts of immunoglobulins IgM and IgT did not show a modulation, nor were the protein levels evaluated in this study.

Insights into the genomic traits of Yersinia frederiksenii, Yersinia intermedia and Yersinia kristensenii isolated from diverse sources in Brazil.

Yersinia is an important genus comprising foodborne, zoonotic and pathogenic bacteria. On the other hand, species of the so-called group Yersinia enterocolitica-like are understudied and mostly characterized as non-pathogenic, despite of some reports of human infections. The present study aimed to provide genomic insights of Yersinia frederiksenii (YF), Yersinia intermedia (YI) and Yersinia kristensenii (YK) isolated worldwide. A total of 22 YF, 20 YI and 14 YK genomes were searched for antimicrobial resistance genes, plasmids, prophages, and virulence factors. Their phylogenomic relatedness was analyzed by Gegenees and core-genome multi-locus sequence typing. Beta-lactam resistance gene blaTEM-116 and five plasmids replicons (pYE854, ColRNAI, ColE10, Col(pHAD28) and IncN3) were detected in less than five genomes. A total of 59 prophages, 106 virulence markers of the Yersinia genus, associated to adherence, antiphagocytosis, exoenzymes, invasion, iron uptake, proteases, secretion systems and the O-antigen, and virulence factors associated to other 20 bacterial genera were detected. Phylogenomic analysis revealed high inter-species distinction and four highly diverse YF clusters. In conclusion, the results obtained through the analyses of YF, YI and YK genomes suggest the virulence potential of these strains due to the broad diversity and high frequency of prophages and virulence factors found. Phylogenetic analyses were able to correctly distinguish these closely related species and show the presence of different genetic subgroups. These data contributed for a better understanding of YF, YI and YK virulence-associated features and global genetic diversity, and reinforced the need for better characterization of these Y. enterocolitica-like species considered non-pathogenic.

Epidemiological cut-off values for Yersina ruckeri disc diffusion data generated by a standardised method.

In order to establish the meaning of data generated in antimicrobial agent susceptibility tests, it is necessary to develop internationally harmonised interpretive criteria. Currently, such criteria have not been developed for data generated in studies of the susceptibility of the fish pathogen Yersinia ruckeri. This work generated the data that would be required to set epidemiological cut-off values for the susceptibility data of this species that had been generated using a standardised disc diffusion method that specified the use of Mueller Hinton agar and incubation at 22°C for 24-28 h. Using this method, sets of inhibition zones data for 4 antimicrobial agents were generated by 3 independent laboratories. The data from these laboratories were aggregated and analysed using the statistically based normalised resistance interpretation. For ampicillin, florfenicol, oxytetracycline and trimethoprim-sulfamethoxazole the cut-off values calculated by this analysis were ≥16, ≥23, ≥24 and ≥30 mm, respectively. Evidence is presented demonstrating that the data for these 4 agents was of sufficient quantity and quality that they could be used by the relevant authorities to set internationally harmonised, consensus epidemiological cut-off values for Y. ruckeri.

Yersinia enterocolitica biovar 1A: An underappreciated potential pathogen in the food chain.

Yersinia enterocolitica is an underreported cause of foodborne gastroenteritis. Little is known of the diversity of Y. enterocolitica isolated from food and which food commodities contribute to human disease. In this study, Y. enterocolitica was isolated from 37/50 raw chicken, 8/10 pork, 8/10 salmon and 1/10 leafy green samples collected at retail in the UK. Up to 10 presumptive Y. enterocolitica isolates per positive sample underwent whole genome sequencing (WGS) and were compared with publicly available genomes. In total, 207 Y. enterocolitica isolates were analyzed and belonged to 38 sequence types (STs). Up to five STs of Y. enterocolitica were isolated from individual food samples and isolates belonging to the same sample and ST differed by 0-74 single nucleotide polymorphisms (SNPs). Biotype was predicted for 205 (99 %) genomes that all belonged to biotype 1A, previously described as non-pathogenic. However, around half (51 %) of food samples contained isolates belonging to the same ST as previously isolated from UK human cases. The closest human-derived isolates shared between 17 and 7978 single nucleotide polymorphisms (SNPs) with the food isolates. Extensive food surveillance is required to determine what food sources are responsible for Y. enterocolitica infections and to re-examine the role of biotype 1A as a human pathogen.

Sepsis due to Yersinia enterocolitica in an aborted equine fetus: case report / Sepse por Yersinia enterocolitica em um feto equino abortado: relato de caso

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.(AU)

Yersinia enterocolitica é uma bactéria com potencial zoonótico, e não há informações desse agente como causa de abortamento em equinos. O objetivo deste relato é descrever um caso de sepse por Y. enterocolitica em um feto equino abortado aos sete meses. O feto foi submetido à necropsia, e amostras de todos os órgãos foram processadas para histopatologia. Para microbiologia, foram coletadas amostras de fígado, pulmão, placenta e conteúdo estomacal. Macroscopicamente, observou-se fígado aumentado com coloração amarelada heterogênea; coração com áreas pálidas no miocárdio; pulmões não colabados, pesados e brilhantes; e cordão umbilical espessado e recoberto por fibrina e pus. Na análise histopatológica, havia miocardite necrossupurativa multifocal moderada e trombose, broncopneumonia supurativa difusa moderada, hepatite fibrinonecrótica multifocal discreta e onfalite necrossupurativa difusa moderada com miríades bacterianas intralesionais e trombose. Observou-se também placentite, nefrite, miosite, cistite e dermatite supurativa multifocal discreta, além de rarefação linfoide difusa discreta. A avaliação microbiológica identificou Y. enterocolitica no fígado, no pulmão e no líquido estomacal. Este é o primeiro relato de sepse por Y. enterocolitica causando abortamento na espécie equina. Essa bactéria tem importância zoonótica, portanto deve ser investigada em casos de abortamento nessa espécie, servindo como diagnóstico diferencial em tal distúrbio reprodutivo.(AU)

Yersiniose em Trachinotus marginatus (pampo): diagnóstico histopatológico e imuno-histoquímico / Yersiniosis in Trachinotus marginatus (pampo): histopathological and immunohistochemical diagnostic

Descreveu-se um surto de yersiniose em uma criação de pampo Trachinotus marginatus estudado no Laboratório de Piscicultura Estuarina e Marinha da Universidade Federal do Rio Grande. A enfermidade manifestou-se por transtornos natatórios, exoftalmia com panoftalmite e pela clássica boca vermelha, nome pelo qual se denomina "enfermidade da boca vermelha" (EBV). Na necropsia, foram observados focos de hemorragia peritoneal, esplenomegalia e hepatomegalia. Microscopicamente, foi observada panoftalmite com infiltrados inflamatórios densos que afetavam quase todas as estruturas oculares. Esses infiltrados estavam constituídos por granulócitos, linfócitos, macrófagos e células granulares eosinofílicas. No exsudado, observaram-se estruturas pequenas, pouco coradas, de aspecto bacteriano Gram negativo. O estudo imuno-histoquímico, que se utilizou de um anticorpo monoclonal anti-Yersinia ruckeri, resultou positivo. Este é o primeiro surto conhecido de yersiniose em Trachinotus marginatus no Brasil.

In the "Laboratório de Piscicultura Estuarina e Marinha da Universidade Federal do Rio Grande" the rearing of Trachinotus marginatus (pompano) is studied, and in one of these rearing a yersioniosis outbreak occured. The disease was manifested by swimming disturbances, exophthalmiawith panophthalmitis and the classic red mouth, (red mouth disease (RMD). The necropsies revealed focus of peritoneal hemorrhage, esplenomegalyand hepatomegaly.Microscopically a panophthalmitis with dense inflammatory infiltrates was observed, which affected almost all ocular structures. These infiltrates were constituted by granulocytes, lymphocytes, macrophages and eosinophylicgranular cells (ECG), in the exudatessmall structures less colored with Gram negative bacteria aspect were observed. The immunohistochemical, which used a monoclonal antibody anti- Yersinia ruckeri waspositive. The RMD is caused by enterobacteriaGram negative, which affects both freshwater and saltwater fish, with predominance in salmonids. This is the first known yersiniosis outbreak in Trachinotus marginatus in Brazil and it is necessary to keep this disease in mind at the moment of rearing fish of this species.

Some bacterial enteropathogens in wildlife and racing pigeons from Trinidad

Fecal and cloacal swabs or feces of wild mammalian, avian and reptilian species, either farmed or free-ranging, and of racing pigeons (Columba livia) kept in lofts were cultured for Salmonella spp., Campylobacter spp., and Yersinia spp. Of 291 free-ranging mammals tested 6 (2 percent) and 1 (< 1 percent) and 1 (< 1 percent) yielded positive culture of Salmonella spp. and Campylobacter spp., respectively. Salmonella newport was the predominant serotype isolated and the opossum (Didelphis marsupialis insularis) had the significantly highest prevalence (29 percent) of Salmonella spp. infection compared to other species such as deer (Mazama americana trinitatis), lappe (Agouti paca), tattoo (Dasypus novemcinctus), agouti (Dasyprocta leporina), and wild hog (Tayassu tajacu). Among 14 species of farmed wildlife studied, 13 (7 percent) and 10 (5 percent) of 184 fecal or cloacal samples tested were positive for Salmonella spp. and Campylobacter spp., respectively. Salmonella javians accounted for 50 percent of the Salmonella spp. isolates and C. jejuni represented 90 percent of the Campylobacter spp. cultured. Only 1 (1 percent) of 124 cloacal swabs of free-flying avian species yielded Salmonella spp. compared to 21 (17 percent) samples positive for Campylobacter spp. Of 171 racing pigeons which originated from 8 fanciers, 8 (5 percent) yielded Salmonella spp. all of which were serotype typhimurium while only 1 (1 percent) were positive for Campylobacter spp. Seven (88 percent) of 8 Salmonella spp. isolates were recovered from one fancier. Yersina spp. was not cultured from any of the above samples. Although the prevalences of Salmonella spp. and Campylobacter spp. in wildlife in Trinidad are low, the practice of wildlife farming and the increased consumption of meat from wildlife may increase the health risk to human consumers(AU)