Virulence Determinants and Genetic Diversity of Yersinia Species Isolated from Retail Meat

Yersinia enterocolitica is an important foodborne pathogen, and the determination of its virulence factors and genetic diversity within the food chain could help understand the epidemiology of yersiniosis. The aim of the present study was to detect the prevalence, and characterize the virulence determinants and genetic diversity, of Yersinia species isolated from meat. A total of 330 samples of retailed beef (n = 150) and pork (n = 180) in Latvia were investigated with culture and molecular methods. Whole genome sequencing (WGS) was applied for the detection of virulence and genetic diversity. The antimicrobial resistance of pathogenic Y. enterocolitica isolates was detected in accordance with EUCAST. Yersinia species were isolated from 24% (79/330) of meats, and the prevalence of Y. enterocolitica in pork (24%, 44/180) was significantly higher (p < 0.05) than in beef (13%, 19/150). Y. enterocolitica pathogenic bioserovars 2/O:9 and 4/O:3 were isolated from pork samples (3%, 6/180). Only resistance to ampicillin was confirmed in Y. enterocolitica 4/O:3 and 2/O:9 isolates, but not in other antimicrobials. Major virulence determinants, including ail, inv, virF, ystA and myfA, were confirmed with WGS in Y. enterocolitica 2/O:9 and 4/O:3. MLST typing revealed 15 STs (sequence types) of Y. enterocolitica with ST12 and ST18, which were associated with pathogenic bioserovars. For Y. enterocolitica 1A, Y. kristensenii, Y. intermedia and Y. frederiksenii, novel STs were registered (ST680-688). The presence of virulence genes and genetic characteristics of certain Y. enterocolitica STs confirm the common knowledge that pork could be an important source of pathogenic Yersinia.

Characterisation of the Bartonella quintana YopJ Homologue

<p><b>Bartonella is a genus of re-emerging bacterial pathogens that typically cause asymptomatic, intra-erythrocytic bacteraemia in their reservoir hosts and are highly specialised to evade host immunity. One of the many mechanisms by which Bartonella spp. modulate the host immune system is the type-IV-secretion system, a protein complex that delivers effector proteins directly into host cells to modulate their function.</b></p> <p>Some Bartonella species, including B. quintana, the causative agent of trench fever, possess an effector protein that is homologous to the effector YopJ of Yersinia species. Yersinia YopJ inhibits the MAPK and NF-kB pathways, and YopJ homologues in other species have similar effects, though through different targets. Very little is known about the function of the B. quintana YopJ homologue, but it may play a role in immune modulation by the bacteria.</p> <p>My aim was to characterise the function of the B. quintana YopJ homologue.</p> <p>I had evidence that it inhibits the NF-kB pathway, so I investigated which step of signalling activation is the target of this inhibition. I also sought to determine whether it impacts signalling pathways other than NF-kB, and to identify the specific host protein that it targets.</p> <p>I performed these investigations using ELISA, high-throughput fluorescence microscopy, Western blotting, LC/MS proteomic screening, and a yeast two-hybrid screen.</p> <p>I found that the B. quintana YopJ homologue inhibits the NF-kB pathway at or upstream of IKK activity, may also impact JNK signalling, the cell cycle, and the mTOR complex, and interacts with the host protein DCNL1, a component of neddylation machinery. Additionally, I determined that this interaction does not impact the neddylation of the protein Cullin-1.</p>

Characterisation of the Bartonella quintana YopJ Homologue

<p><b>Bartonella is a genus of re-emerging bacterial pathogens that typically cause asymptomatic, intra-erythrocytic bacteraemia in their reservoir hosts and are highly specialised to evade host immunity. One of the many mechanisms by which Bartonella spp. modulate the host immune system is the type-IV-secretion system, a protein complex that delivers effector proteins directly into host cells to modulate their function.</b></p> <p>Some Bartonella species, including B. quintana, the causative agent of trench fever, possess an effector protein that is homologous to the effector YopJ of Yersinia species. Yersinia YopJ inhibits the MAPK and NF-kB pathways, and YopJ homologues in other species have similar effects, though through different targets. Very little is known about the function of the B. quintana YopJ homologue, but it may play a role in immune modulation by the bacteria.</p> <p>My aim was to characterise the function of the B. quintana YopJ homologue.</p> <p>I had evidence that it inhibits the NF-kB pathway, so I investigated which step of signalling activation is the target of this inhibition. I also sought to determine whether it impacts signalling pathways other than NF-kB, and to identify the specific host protein that it targets.</p> <p>I performed these investigations using ELISA, high-throughput fluorescence microscopy, Western blotting, LC/MS proteomic screening, and a yeast two-hybrid screen.</p> <p>I found that the B. quintana YopJ homologue inhibits the NF-kB pathway at or upstream of IKK activity, may also impact JNK signalling, the cell cycle, and the mTOR complex, and interacts with the host protein DCNL1, a component of neddylation machinery. Additionally, I determined that this interaction does not impact the neddylation of the protein Cullin-1.</p>

A Case Series of Diarrheal Diseases Associated with Yersinia frederiksenii

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.

Heightened virulence of Yersinia is associated with decreased function of the YopJ protein

Despite the maintenance of YopP/J alleles throughout the human-pathogenic Yersinia lineage, the benefit of YopP/J-induced phagocyte death for Yersinia pathogenesis in animals is not obvious. To determine how sequence divergence of YopP/J has impacted Yersinia virulence, we examined protein polymorphisms in this Type III secreted effector protein across 17 Yersinia species, and tested the consequences of polymorphism in a murine model of sub-acute systemic yersiniosis. Our evolutionary analysis revealed that codon 177 has been subjected to positive selection - the Y. enterocolitica residue had been altered from a leucine to a phenylalanine in nearly all Y. pseudotuberculosis and Y. pestis strains examined. Despite being a minor change, as both leucine and phenylalanine have hydrophobic side chains, reversion of YopJF177 to the ancestral YopJL177 variant yielded a Y. pseudotuberculosis strain with enhanced cytotoxicity towards macrophages, consistent with previous findings. Surprisingly, expression of YopJF177L in the mildly attenuated ksgA- background rendered the strain completely avirulent in mice. Consistent with this hypothesis that YopJ activity indirectly relates to Yersinia pathogenesis in vivo, ksgA- strains lacking functional YopJ failed to kill macrophages but actually regained virulence in animals. Also, treatment with the anti-apoptosis drug suramin prevented YopJ-mediated macrophage cytotoxicity and enhanced Y. pseudotuberculosis virulence in vivo. Our results demonstrate that Yersinia-induced cell death is detrimental for bacterial pathogenesis in this animal model of illness, and indicate that positive selection has driven YopJ/P and Yersinia evolution towards diminished cytotoxicity and increased virulence, respectively.

Elastic Light Scatter Pattern Analysis for the Expedited Detection of Yersinia Species in Pork Mince: Proof of Concept

Isolation of the pathogens Yersinia enterocolitica and Yersinia pseudotuberculosis from foods typically rely on slow (10–21 day) “cold enrichment” protocols before confirmed results are obtained. We describe an approach that yields results in 39 h that combines an alternative enrichment method with culture on a non-selective medium, and subsequent identification of suspect colonies using elastic light scatter (ELS) analysis. A prototype database of ELS profiles from five Yersinia species and six other bacterial genera found in pork mince was established, and used to compare similar profiles of colonies obtained from enrichment cultures from pork mince samples seeded with representative strains of Y. enterocolitica and Y. pseudotuberculosis. The presumptive identification by ELS using computerised or visual analyses of 83/90 colonies in these experiments as the target species was confirmed by partial 16S rDNA sequencing. In addition to seeded cultures, our method recovered two naturally occurring Yersinia strains. Our results indicate that modified enrichment combined with ELS is a promising new approach for expedited detection of foodborne pathogenic yersiniae.

Infective Endocarditis by Yersinia Species: A Systematic Review

Yersinia spp. are non-spore-forming Gram-negative bacilli. They comprise only three species known to cause disease in humans, namely Y. pestis, Y. enterocolitica and Y. pseudotuberculosis. Since infective endocarditis (IE) is rarely caused by Yersinia, the management of these infections can be problematic due to the lack of experience. The purpose of this study was to systematically review all published cases of IE by Yersinia species in the literature. A systematic review of PubMed, Scopus and Cochrane Library (through 1 November 2020) for studies providing epidemiological, clinical and microbiological information as well as data on treatment and outcomes of IE caused by Yersinia species was performed. A total of 12 studies, containing data of 12 patients, were included. A prosthetic valve was present in 17% of patients. The mitral valve was the most commonly infected site, followed by the aortic valve. Fever, sepsis and embolic phenomena were common clinical signs, followed by heart failure. Aminoglycosides, cephalosporins and quinolones were the most commonly used antimicrobials. Clinical cure was noted in 83%, while overall mortality was 17%. This systematic review describes IE by Yersinia and provides information on patients’ epidemiology, clinical signs and the related therapeutic strategies and outcomes.

Prevalence, antibiotic susceptibility, and virulence factors of Yersinia enterocolitica isolated from raw milk in Basrah, Iraq

A total of one hundred and fifty cow, buffalo, and sheep milk samples were collected from several markets in Basrah, Iraq (50 samples from each species). All milk samples were subjected to enrichment in TSB and cold enrichment in PBS, then cultured on YSA agar in order to obtain Yersinia species. The highest growth obtained by TSB enrichment was seen in cow milk (24%) followed by buffalo milk (22%) and sheep milk (12%). The results of PBS enrichment showed the highest growth in cow milk (14%) followed by buffalo (8%) and sheep milk (2%). The results showed that both cow and buffalo milk samples were contaminated by Y. enterocolitica at 8% while the prevalence in sheep milk was 4%. Ten isolates from different sources in the current study were examined for their susceptibility to 10 antibiotics. The highest susceptibility (100%) was found towards streptomycin, azithromycin and gentamicin, followed by ciprofloxacin and chloramphenicol, 93.3% for each. Low susceptibility was found toward vancomycin (6.66%) and cloxacillin (33.3%). 16S rRNA sequencing showed homology with previously annotated strains at GenBank of National Centre for Biotechnology (NCBI). Multiple sequence alignments exhibited one difference between the sequences at the locus 764. The phylogenic tree of the results demonstrated that the local isolates were closely related to strains previously reported from China. All Yersinia enterocolitica strains had the inv gene. In contrast, the ail gene was found in one strain (10%) while the yad gene appeared in 50% of the investigated strains.

Detection of Zoonotic Yersinia Infection in Symptomatic and Asymptomatic Dogs in Sokoto State Nigeria

Background: Zoonotic Yersinia infection has been previously reported in humans and animal hosts in Nigeria, occasionally with fulminant disease. Despite earlier evidence of Yersinia pathogen circulating in human and animal populations in Nigeria, studies and suspicion index to Yersinia is below an acceptable average amongst clinicians, diagnosticians, academics and health policy officers. Methods: The deoxycholate Citrate Agar (DCA) was used as a selective media to culture Yersinia, preceded by inoculation in MacConkay agar. Plates with evident growth in the differential media consistent with reported accounts for Yersinia were picked and inoculated in selective medium and left for 48 hours until growth was seen, other samples were left until five days before being discarded as negative. Pure cultures were subjected to a comprehensive biochemical test standard and previously applied for diagnosis and discrimination of Yersinia species. Result: This research recorded an overall microbial prevalence of 30%. Prevalence of Yersinia enterocolitica was 18.3% and Y. pseudotuberculosis 11.7%. Male dogs presented a relative prevalence of Y. enterocolitica 40.9% compared with 59.1% recorded for female dogs. Symptomatic dogs presented a relative prevalence of Y. enterocolitica of 86.4% and Y. pseudotuberculosis of 71.4%

Detection of Zoonotic Yersinia Infection in Symptomatic and Asymptomatic Dogs in Sokoto State Nigeria

Background: Zoonotic Yersinia infection has been previously reported in humans and animal hosts in Nigeria, occasionally with fulminant disease. Despite earlier evidence of Yersinia pathogen circulating in human and animal populations in Nigeria, studies and suspicion index to Yersinia is below an acceptable average amongst clinicians, diagnosticians, academics and health policy officers. Methods: The Deoxycholate Citrate Agar (DCA) was used as selective media to culture Yersinia preceded by inoculation in MacConkay agar. Plates with evident growth in the differential media consistent with reported accounts for Yersinia were picked and inoculated in selective medium and left for 48 hours until growth was seen, other samples left until five days before being discarded as negative. Pure cultures were subjected to comprehensive biochemical tests standard and previously applied for diagnosis and discrimination of Yersinia species. Result: This research recorded an overall microbial prevalence of 30%. Prevalence of Yersinia enterocolitica was 18.3% and Y. pseudotuberculosis 11.7%. Male dogs presented a relative prevalence of Y.