Yersinia enterocolitica: Epidemiological Studies and Outbreaks

The implication of viability and pathogenicity by truncated lipopolysaccharide in Yersinia enterocolitica

The fast envelope stress responses play a key role in the transmission and pathogenesis of Yersinia enterocolitica, one of the most common foodborne pathogens. Our previous study showed that deletion of the waaF gene, essential for the biosynthesis of lipopolysaccharide (LPS) core polysaccharides, led to the formation of a truncated LPS structure and induced cell envelope stress. This envelope stress may disturb the intracellular signal transduction, thereby affecting the physiological functions of Y. enterocolitica. In this study, truncated LPS caused by waaF deletion was used as a model of envelope stress in Y. enterocolitica. We investigated the mechanisms of envelope stress responses and the cellular functions affected by truncated LPS. Transcriptome analysis and phenotypic validation showed that LPS truncation reduced flagellar assembly, bacterial chemotaxis, and inositol phosphate metabolism, presenting lower pathogenicity and viability both in vivo and in vitro environments. Further 4D label-free phosphorylation analysis confirmed that truncated LPS perturbed multiple intracellular signal transduction pathways. Specifically, a comprehensive discussion was conducted on the mechanisms by which chemotactic signal transduction and Rcs system contribute to the inhibition of chemotaxis. Finally, the pathogenicity of Y. enterocolitica with truncated LPS was evaluated in vitro using IPEC-J2 cells as models, and it was found that truncated LPS exhibited reduced adhesion, invasion, and toxicity of Y. enterocolitica to IPEC-J2 cells. Our research provides an understanding of LPS in the regulation of Y. enterocolitica viability and pathogenicity and, thus, opening new avenues to develop novel food safety strategies or drugs to prevent and control Y. enterocolitica infections. KEY POINTS: • Truncated LPS reduces flagellar assembly, chemotaxis, and inositol phosphate metabolism in Y. enterocolitica. • Truncated LPS reduces adhesion, invasion, and toxicity of Y. enterocolitica to IPEC-J2 cells. • Truncated LPS regulates intracellular signal transduction of Y. enterocolitica.

Infectious Mimics of Inflammatory Bowel Disease

Distinguishing inflammatory bowel disease (IBD) from its mimics remains a diagnostic challenge for surgical pathologists. Several gastrointestinal infections produce inflammatory patterns that overlap with typical findings of IBD. Although stool culture, PCR, and other clinical assays may identify infectious enterocolitides, these tests may not be performed or the results may be unavailable at the time of histologic evaluation. Furthermore, some clinical tests, including stool PCR, may reflect past exposure rather than ongoing infection. It is important for surgical pathologists to be knowledgeable about infections that simulate IBD in order to generate an accurate differential diagnosis, perform appropriate ancillary studies, and prompt clinical follow-up. This review covers bacterial, fungal, and protozoal infections in the differential diagnosis of IBD.

Ultra-Sensitive and Rapid Detection of Pathogenic Yersinia enterocolitica Based on the CRISPR/Cas12a Nucleic Acid Identification Platform

Yersinia enterocolitica is a dangerous foodborne human pathogen that mainly causes gastroenteritis. Ideal methods for the detection of pathogens in food should be rapid, sensitive, specific, and cost effective. To this end, novel in vitro nucleic acid identification methods based on clustered, regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) endonuclease have received increasing attention. In this study, a simple, visual, and ultrasensitive method, based on CRISPR/Cas12a with recombinase polymerase amplification (RPA), was developed for the detection of Y. enterocolitica. The results show that a specific attachment invasion locus gene (ail) can be rapidly detected using a CRISPR/Cas12a-RPA-based system. Application of the method to raw pork, which was artificially infected with Y. enterocolitica, achieved an estimated detection limit of 1.7 CFU/mL in less than 45 min, and this was 100 times lower compared with qPCR. The results indicated that the CRISPR/Cas12a-RPA system has good potential for monitoring pathogenic Y. enterocolitica in the chilled meat supply chain.

Isolation and characterization of Yersinia enterocolitica from foods in Apulia and Basilicata regions (Italy) by conventional and modern methods

Yersiniosis is the third most reported food-borne zoonosis in Europe. The aim of the present study was to perform the search for Yersinia enterocolitica in food samples collected from Apulia and Basilicata regions (Southern Italy) and to characterize any isolates by classical and modern analytical methods. A total of 130 samples were analyzed between July 2018 and July 2019: most of them were raw milk and dairy products made from it. Furthermore, 8 out of 130 samples were individual milk samples collected from bovines reared in a Brucella-free farm which showed false positive serological reaction for brucellosis due to the presence of pathogenic Y. enterocolitica O:9 biotype 2 in faeces. The Real Time PCR targeting the ail gene and the culture method were performed to detect pathogenic Y. enterocolitica. Isolates were subjected to API 20E (Biomerieux) and MALDI-TOF MS (Matrix Assisted Laser Desorption Ionization Time-of-Flight) for species identification. All samples were negative for the ail gene. The culture method allowed to isolate suspicious colonies from 28 samples. The API 20E system and the MALDI-TOF MS technique identified 20 Y. enterocolitica and 1 Y. intermedia in a concordant way. The remaining 7 strains were all identified as Y. enterocolitica by the API 20E system, while the MALDI-TOF MS recognized 4 Y. intermedia, 1 Y. bercovieri and 2 Y. massiliensis. Genotypic characterization of the discordant strains was performed by rMLST and it confirmed the MALDI-TOF MS' results. Only non-pathogenic Y. enterocolitica biotype 1A strains were found, although with a non-negligible prevalence (P = 0.15 with CI 95% = ± 0.06). This study indicates a poor circulation of pathogenic Y. enterocolitica in food products made and marketed in the investigated areas. However, the small number of samples, insufficient for some food categories such as meat and vegetable, does not allow to exclude the presence of pathogenic strains at all.

Global Prevalence of Yersinia enterocolitica in Cases of Gastroenteritis: A Systematic Review and Meta-Analysis

The prevalence of Yersinia enterocolitica in gastroenteritis is often underestimated. It relates considerably to morbidity and medical expenses around the world. Understanding the cause of gastroenteritis leads to making the appropriate treatment decisions. We systematically searched PubMed, Science Direct, Embase, and Scopus to identify all published studies between Jan. 1, 2000, and Dec. 31, 2019, to assess the prevalence of Y. enterocolitica in gastroenteritis patients. A total of 5039 articles were identified that lead to the extraction of data from 47 of them. The pooled prevalence of Y. enterocolitica in cases of gastroenteritis was estimated as 1.97% (1.32–2.74%) in the culture method and 2.41% (1.07–4.22%) in the molecular method. Among the biotypes of Y. enterocolitica, 1A (62.48%) and 1B (2.14%) had the most and least prevalence, respectively. Serotype O3 Y. enterocolitica with 39.46% had the highest and O5,27 with 0.0% had the least prevalence in gastroenteritis cases. In conclusion, the findings of this systematic review show that Y. enterocolitica is prevalent in gastroenteritis in all age groups. Serotypes O3 and O9 of Y. enterocolitica had the highest prevalence and O5,27 had the least prevalence in diarrheal patients. The prevalence of Y. enterocolitica was similar in both gender and different seasons. It should be noted that to determine the role of the organism, more studies are needed especially in food-borne diseases.

Transmission modelling of environmentally persistent zoonotic diseases: a systematic review

Transmission of many infectious diseases depends on interactions between humans, animals, and the environment. Incorporating these complex processes in transmission dynamic models can help inform policy and disease control interventions. We identified 20 diseases involving environmentally persistent pathogens (ie, pathogens that survive for more than 48 h in the environment and can cause subsequent human infections), of which indirect transmission can occur from animals to humans via the environment. Using a systematic approach, we critically appraised dynamic transmission models for environmentally persistent zoonotic diseases to quantify traits of models across diseases. 210 transmission modelling studies were identified and most studies considered diseases of domestic animals or high-income settings, or both. We found that less than half of studies validated their models to real-world data, and environmental data on pathogen persistence was rarely incorporated. Model structures varied, with few studies considering the animal-human-environment interface of transmission in the context of a One Health framework. This Review highlights the need for more data-driven modelling of these diseases and a holistic One Health approach to model these pathogens to inform disease prevention and control strategies.

Molecular Characterization of Multidrug-Resistant Yersinia enterocolitica From Foodborne Outbreaks in Sweden

The foodborne pathogen Yersinia enterocolitica causes gastrointestinal infections worldwide. In the spring of 2019, the Swedish Public Health Agency and Statens Serum Institut in Denmark independently identified an outbreak caused by Yersinia enterocolitica 4/O:3 that after sequence comparison turned out to be a cross-border outbreak. A trace-back investigation suggested shipments of fresh prewashed spinach from Italy as a common source for the outbreak. Here, we determined the genome sequences of five Y. enterocolitica clinical isolates during the Swedish outbreak using a combination of Illumina HiSeq short-read and Nanopore Technologies’ MinION long-read whole-genome sequencing. WGS results showed that all clinical strains have a fully assembled chromosome of approximately 4.6 Mbp in size and a 72-kbp virulence plasmid; one of the strains was carrying an additional 5.7-kbp plasmid, pYE-tet. All strains showed a high pathogen probability score (87.5%) with associated genes for virulence, all of which are closely related to an earlier clinical strain Y11 from Germany. In addition, we identified a chromosomally encoded multidrug-resistance cassette carrying resistance genes against chloramphenicol (catA1), streptomycin (aadA1), sulfonamides (sul1), and a mercury resistance module. This chromosomally encoded Tn2670 transposon has previously been reported associated with IncFII plasmids in Enterobacteriaceae: a Shigella flexneri clinical isolate from Japan in 1950s, a Klebsiella pneumoniae outbreak from Australia in 1997, and Salmonella enterica serovar Typhimurium. Interestingly, we identified an additional 5.7-kbp plasmid with tetB (encoding an ABC transporter), Rep, and its own ORI and ORIt sites, sharing high homology with small tetB-Rep plasmids from Pasteurellaceae. This is the first time that Tn2670 and Pasteurellaceae plasmids have been reported in Y. enterocolitica. Taken together, our study showed that the Swedish Y. enterocolitica outbreak strains acquired multi-antibiotic and metal-resistance genes through horizontal gene transfer, suggesting a potential reservoir of intraspecies dissemination of multidrug-resistance genes among foodborne pathogens. This study also highlights the concern of food-chain contamination of prewashed vegetables as a perpetual hazard against public health.

Monitoring microbial growth on a microfluidic lab-on-chip with electrochemical impedance spectroscopic technique

A continuous rise in the wastes from industrial effluents, bio-waste, and pharmaceuticals has deteriorated surface water and drinking water sources. Standard laboratory tests of total coliform are time-consuming and logistically inefficient for field data generation. Better and portable sensing technologies are needed. This paper reports an electrical impedance spectroscopic technique incorporated in a micro-fluidic chip with interdigitated microelectrodes to monitor the growth of microbial cells. Lag, log, and stationary phases of Escherichia coli cell growth with an integrated electrode are successfully detected, for samples of reverse osmosis water, standard treated tap water, and recycled water respectively. The results indicate that reverse osmosis water has a higher probability of contamination with bacterial pathogens compared to the other two types of water samples when subjected to the same amount of added nutrients. The statistical analysis shows a possible single detection range with higher-order regression, and repeat use of a single chip with the electrode was found to be within an acceptable limit. The interdigitated electrodes exposed to in-situ cell growth conditions and repeated electrical measurements have shown a promise for possible periodic or continuous monitoring. The paper further identifies several complimentary analysis methodologies that are robust towards phase noise in the measured impedance and are suited particularly for early-stage detection of bacterial contamination. The cell adhesion tendencies over the microelectrode due to the electric field need to be further analyzed.

Rcs Phosphorelay Responses to Truncated Lipopolysaccharide-Induced Cell Envelope Stress in Yersinia enterocolitica

Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria, and its integrity is monitored by various stress response systems. Although the Rcs system is involved in the envelope stress response and regulates genes controlling numerous bacterial cell functions of Yersinia enterocolitica, whether it can sense the truncated LPS in Y. enterocolitica remains unclear. In this study, the deletion of the Y. enterocolitica waaF gene truncated the structure of LPS and produced a deep rough LPS. The truncated LPS increased the cell surface hydrophobicity and outer membrane permeability, generating cell envelope stress. The truncated LPS also directly exposed the smooth outer membrane to the external environment and attenuated the resistance to adverse conditions, such as impaired survival under polymyxin B and sodium dodecyl sulfate (SDS) exposure. Further phenotypic experiment and gene expression analysis indicated that the truncated LPS was correlated with the activation of the Rcs phosphorelay, thereby repressing cell motility and biofilm formation. Our findings highlight the importance of LPS integrity in maintaining membrane function and broaden the understanding of Rcs phosphorelay signaling in response to cell envelope stress, thus opening new avenues to develop effective antimicrobial agents for combating Y. enterocolitica infections.

Evaluation of a human-associated genetic marker for Escherichia coli (H8) for fecal source tracking in Thailand

High levels of microbial fecal pollution are a major concern in many countries. A human-associated genetic marker for Escherichia coli (H8) has recently been developed for fecal source tracking. The assessment of the H8 marker performance is crucial before it can be applied as a suitable method for fecal source tracking in each country. The performance (specificity and sensitivity) of the H8 marker was evaluated by using non-target host groups (cattle, buffalo, chicken, duck, and pig feces) and target host groups (influent and effluent from a wastewater treatment plant and septages). SYBR based real-time PCR (polymerase chain reaction) was done on 400 E. coli isolates from non-target and target host groups after E. coli isolation. It was found that the specificity from animal feces samples collected in Thailand was 96%. Moreover, influent, effluent, and septage samples showed the values of the sensitivity at 18, 12, and 36%, respectively. All of the non-target host groups were found to be significantly different with positive proportions from the target host group (septage samples) (p ≤ 0.01). Based on the results, this marker is recommended for use as a human-associated E. coli marker for identifying sources of fecal pollution in Thailand.

Molecular evaluation of quorum quenching potential of vanillic acid against Yersinia enterocolitica through transcriptomic and in silico analysis

Introduction. Yersinia enterocolitica is one of the leading food-borne entero-pathogens causing various illnesses ranging from gastroenteritis to systemic infections. Quorum sensing (QS) is one of the prime mechanisms that control the virulence in Y. enterocolitica .

Hypothesis/Gap Statement. Vanillic acid inhibits the quorum sensing and other virulence factors related to Y. enterocolitica . It has been evaluated by transcriptomic and Insilico analysis. Therefore, it can be a prospective agent to develop a therapeutic combination against Y. enterocolitica .

Aim. The present study is focused on screening natural anti-quorum-sensing agents against Y. enterocolitica . The effect of selected active principle on various virulence factors was evaluated.

Methodology. In total, 12 phytochemicals were screened by swarming assay. MATH assay, EPS and surfactant production assay, SEM analysis, antibiotic and blood sensitivity assay were performed to demonstrate the anti-virulence activity. Further, RNA sequencing and molecular docking studies were carried out to substantiate the anti-QS activity.

Results. Vanillic acid (VA) has exhibited significant motility inhibition, thus indicating the anti-QS activity with MQIC of 400 µg ml−1 without altering the cell viability. It has also inhibited the violacein production in Chromobacterium violaceum ATCC 12472, which further confirms the anti-QS activity. VA has inhibited 16 % of cell-surface hydrophobicity (CSH), 52 % of EPS production and 60 % of surfactant production. Moreover, it has increased the sensitivity of Y. enterocolitica towards antibiotics. It has also made the cells upto 91 % more vulnerable towards human immune cells. The transcriptomic analysis by RNA sequencing revealed the down regulation of genes related to motility, virulence, chemotaxis, siderophores and drug resistance. VA treatment has also positively regulated the expression of several stress response genes. In furtherance, the anti-QS potential of VA has been validated with QS regulatory protein YenR by in silico molecular simulation and docking study.

Conclusion. The present study is possibly the first attempt to demonstrate the anti-QS and anti-pathogenic potential of VA against Y. enterocolitica by transcriptomic and in silico analysis. It also deciphers that VA can be a promising lead to develop biopreservative and therapeutic regimens to treat Y. enterocolitica infections.

The role of osmoregulated periplasmic glucans in the biofilm antibiotic resistance of Yersinia enterocolitica

The formation of biofilms by bacteria is of great significance because it involves many physiological changes that serve to protect the cells from various stresses. One of the best-known biofilm-specific properties of bacteria is that bacteria that grow in biofilms are generally more resistant to antibiotics than their planktonic counterparts. In a previous study, osmoregulated periplasmic glucans (OPGs), catalyzed by the opgGH operon, were identified and found to function in Rcs signalling in Yersinia enterocolitica. In this study, the possible contribution of OPGs to antimicrobial resistance of Y. enterocolitica biofilms were investigated, and the results showed that OPGs, especially when overexpressed, conferred a high level of biofilm resistance to two different classes of antibiotics onto Y. enterocolitica. Subsequent analysis revealed that OPGs regulated the biofilm architecture in Y. enterocolitica by promoting the bacteria to form large cell aggregates. Moreover, the opgGH genes in biofilms showed higher expression than in planktonic cultures. OPGs were required to induce the expression of genes related to flagella, extracellular polysaccharide, and c-di-GMP biosynthesis in Y. enterocolitica biofilms and this effect was more significant when OPGs were overproduced. The current investigation showed an extension in the biological role of OPGs in Y. enterocolitica and provided a strong theoretical basis to further study this resistance mechanism at the molecular level to identify new drug targets or disinfectants for the treatment of infections caused by Y. enterocolitica within biofilms.

Transcriptomic analysis reveals the role of RcsB in suppressing bacterial chemotaxis, flagellar assembly and infection in Yersinia enterocolitica

Defining the Rcs (Regulator of Capsule Synthesis) regulon in Enterobacteriaceae has been the major focus of several recent studies. The overall role of the Rcs system in Yersinia enterocolitica is largely unknown. Our previous study showed that RcsB inhibits motility, biofilm formation and c-di-GMP production by negatively regulating flhDC, hmsHFRS and hmsT expression. To identify other cellular functions regulated by the RcsB, gene expression profiles of the wild type and ΔrcsB mutant were compared by RNA-Seq in this study. A total of 132 differentially expressed genes regulated by the RcsB have been identified, of which 114 were upregulated and 18 were downregulated. Further, the results of RNA sequencing were discussed with a focus on the predictive roles of RcsB in the inhibition of bacterial chemotaxis, flagellar assembly and infection. To confirm these predictions, we experimentally verified that the ΔrcsB mutant activated chemotactic behavior and flagella biosynthesis, and exhibited enhanced adhesion and invasion of Y. enterocolitica to Caco-2 cells. Although RcsB largely inhibits these physiological activities, the presence of RcsB is still of great significance for optimizing the survival of Y. enterocolitica as evidenced by our previous report that RcsB confers some level of resistance to the cationic antimicrobial peptide polymyxin B in Y. enterocolitica. Overall, the information provided in this study complements our understanding of Rcs phosphorelay in the regulation of Y. enterocolitica pathogenicity, and, simultaneously, provides clues to additional roles of the Rcs system in other members of family Enterobacteriaceae.

Emerging and re-emerging bacterial zoonoses in Nigeria: current preventive measures and future approaches to intervention

A characteristic of bacterial zoonoses, diseases caused by bacteria that can be transmitted to humans from animals, is a propensity to re-emerge. Several studies demonstrate their ongoing transmission in Nigeria, the most populous country in Africa. However, as local epidemiological data on bacterial zoonoses are inadequate the extent and impact of these infectious diseases is under-reported. Consequently, they are not a targeted priority of national public health policies. This limited recognition is despite indications of their possible roles in the widespread prevalence of non-malarial undifferentiated fever in Nigeria. While a number of animal reservoirs and arthropod vectors have been identified in the transmission routes of these diseases, an escalation of cases of undiagnosed febrile illness highlights the urgent need for a comprehensive assessment of other potential reservoirs, vectors and transmission cycles that may increase the local risk of infection with bacterial zoonoses. Animal health interventions have been proposed as a cost-effective strategy. Here, we present a broad overview of bacterial zoonotic infections of humans in Nigeria in the context of evolving epidemiological patterns. Further, we propose that facilitating the operation of a community-based One Health program is essential to providing the comprehensive epidemiological information that is required to improve prioritization of bacterial zoonoses. This would provide a driver for much needed investment in relevant public health interventions in Africa's most populous country.

Whole Food–Based Approaches to Modulating Gut Microbiota and Associated Diseases

Intake of whole foods, such as fruits and vegetables, may confer health benefits to the host. The beneficial effects of fruits and vegetables were mainly attributed to their richness in polyphenols and microbiota-accessible carbohydrates (MACs). Components in fruits and vegetables modulate composition and associated functions of the gut microbiota, whereas gut microbiota can transform components in fruits and vegetables to produce metabolites that are bioactive and important for health. The progression of multiple diseases, such as obesity and inflammatory bowel disease, is associated with diet and gut microbiota. Although the exact causality between these diseases and specific members of gut microbiota has not been well characterized, accumulating evidence supported the role of fruits and vegetables in modulating gut microbiota and decreasing the risks of microbiota-associated diseases. This review summarizes the latest findings on the effects of whole fruits and vegetables on gut microbiota and associated diseases.

Osmoregulated Periplasmic Glucans Transmit External Signals Through Rcs Phosphorelay Pathway in Yersinia enterocolitica

Fast response to environmental changes plays a key role in the transmission and pathogenesis of Yersinia enterocolitica. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several Enterobacteriaceae pathogens; however, the biological function of OPGs in Y. enterocolitica is still unclear. In this study, we investigated the role of OPGs in Y. enterocolitica by deleting the opgGH operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the ΔopgGH mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of opgGH expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of Y. enterocolitica. Gene expression analysis revealed that opgGH deletion reduced transcription of flhDC, ftsAZ, hmsT and hmsHFRS genes regulated by the Rcs phosphorelay system, whereas additional deletion of rcs family genes (rcsF, rcsC, or rcsB) reversed this effect and restored motility and c-di-GMP/biofilm production but further reduced cell size. Furthermore, disruption of the Rcs phosphorelay increased the motility and promoted the induction of biofilm and c-di-GMP production regulated by OPGs through upregulating the expression of flhDC, hmsHFRS, and hmsT. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the flhDC, hmsHFRS and hmsT expression, leading to the decreased motility and prevented the induction of biofilm and c-di-GMP production regulated by OPGs. These results indicated that Rcs phosphorelay had the effect on OPGs-mediated functional responses in Y. enterocolitica. Our findings disclose part of the biological role of OPGs and the underlying molecular mechanisms associated with Rcs system in the regulation of the pathogenic phenotype in Y. enterocolitica.

An overview of Yersinia enterocolitica and related species in samples of different origin from San Luis, Argentina

This study is aimed at offering an overview of the prevalence of Yersinia enterocolitica and related species in San Luis, Argentina, from samples of diverse origin received in our laboratory between 1984 and 2014, and providing an analysis of the distribution of Yersinia isolates according to their isolation sources, highlighting bioserotypes and potential reservoirs and vehicles of transmission to humans. From a total of 4572 samples of human, animal, food and environmental origins analyzed by traditional culture methods and molecular techniques, 229 (5%) samples were Yersinia positive. The highest frequency of Yersinia isolates was observed in environmental specimens (14.3%), followed by animal (9.2%), food (5%) and human (0.6%) samples. A total of 255 Yersinia isolates were characterized, including 183 Y. enterocolitica and 72 isolates of other Yersinia species. Biotype 1A associated to several serotypes was identified in Y. enterocolitica isolates from environment (100%), animals (95.5%), foods (71.7%) and human samples (40%); bioserotype 2/O:9 was identified in isolates from foods (25.5%), and biotype 3 was associated with strains from humans (60%), animals (4.5%) and foods (2.8%). This biotype included three strains O:3 and six strains O:5. The data highlight animals and foods as the main Y. enterocolitica sources in our region.

Application of data science in risk assessment and early warning

The food supply chain has been recognised by the EU as a critical infrastructure, and its complexity is the main cause of vulnerability. Depending on the food matrix, natural and/or deliberate contamination, food-borne diseases or even food fraud incidents may occur worldwide. Consequently, robust predictive models and/or software tools are needed to support decision-making and mitigating risks in an efficient and timely manner. In this frame, the fellow participated in data collection and analysis tasks, so as to provide additional predictive models. The working programme, covered a wide range of aspects related to risk assessment including identification of emerging risks (quantitative), microbiological risk assessment, authenticity assessment, spatio-temporal epidemiological modelling and database formation for hosting predictive microbial models. The training and close integration, in the open-source, in-house (German Federal Institute for Risk Assessment (BfR)) developed software tools under the framework of FoodRisk-Labs (https://foodrisklabs.bfr.bund.de.) for data analysis, predictive microbiology, quantitative microbiological risk assessment and automatic data retrieval purposes allowed for the independent use. Moreover, the fellow actively contributed to the update of the upcoming Yersinia enterocolitica risk assessment, and also in authenticity assessment of edible oils. Over the course of the year, the fellow was closely involved in international and national research projects with experts in the above-mentioned disciplines. Lastly, he consolidated his acquired knowledge by presenting his scientific work to conferences, and BfR-internal meetings.

Gut Microbiota and Colonization Resistance against Bacterial Enteric Infection

The gut microbiome is critical in providing resistance against colonization by exogenous microorganisms. The mechanisms via which the gut microbiota provide colonization resistance (CR) have not been fully elucidated, but they include secretion of antimicrobial products, nutrient competition, support of gut barrier integrity, and bacteriophage deployment. However, bacterial enteric infections are an important cause of disease globally, indicating that microbiota-mediated CR can be disturbed and become ineffective. Changes in microbiota composition, and potential subsequent disruption of CR, can be caused by various drugs, such as antibiotics, proton pump inhibitors, antidiabetics, and antipsychotics, thereby providing opportunities for exogenous pathogens to colonize the gut and ultimately cause infection. In addition, the most prevalent bacterial enteropathogens, including Clostridioides difficile, Salmonella enterica serovar Typhimurium, enterohemorrhagic Escherichia coli, Shigella flexneri, Campylobacter jejuni, Vibrio cholerae, Yersinia enterocolitica, and Listeria monocytogenes, can employ a wide array of mechanisms to overcome colonization resistance. This review aims to summarize current knowledge on how the gut microbiota can mediate colonization resistance against bacterial enteric infection and on how bacterial enteropathogens can overcome this resistance.

Investigation of a Yersinia enterocolitica outbreak in a commercial alpaca farm in Saskatchewan

An outbreak of enterocolitis and sudden deaths occurred in an alpaca herd in Saskatchewan (mortality rate: 18.6%). Yersinia enterocolitica was isolated from the intestine, liver, and spleen of the index case, the kidney of a second case, and the feces of affected animals. The initial source of infection could not be identified. Treatment with oxytetracycline was followed by resolution of diarrhea and arrest of fatalities. The end of the outbreak was determined by absence of new cases and negative fecal cultures. This is the first report of a presumed herd outbreak of yersiniosis in camelids in North America.

A Combined YopB and LcrV Subunit Vaccine Elicits Protective Immunity against Yersinia Infection in Adult and Infant Mice

Yersinia enterocolitica causes a severe enteric infection in infants and young children. There is no vaccine approved for use in humans. We investigated the immunogenicity and protective capacity of Yersinia YopB, a conserved type III secretion system protein, alone or combined with LcrV in adult mice immunized intranasally. YopB or LcrV (5 μg) administered with the Escherichia coli double mutant heat-labile toxin (dmLT) adjuvant afforded modest (10-30%) protection against lethal Y. enterocolitica oral infection. The combination of YopB and LcrV (5 μg each) dramatically improved vaccine efficacy (70-80%). Additionally, it afforded complete protection against Y. pestis pulmonary infection. Immunization with YopB/LcrV+dmLT resulted in Ag-specific serum IgG, systemic and mucosal Ab-secreting cells, as well as IFN-γ, TNF-α, IL-2, IL-6, IL-17A, and KC production by spleen cells. Serum Abs elicited by YopB/LcrV+dmLT had enhanced bactericidal and opsonophagocytic killing activity. After Y. enterocolitica challenge, YopB/LcrV+dmLT-vaccinated mice exhibited intact intestinal tissue, active germinal centers in mesenteric lymph nodes, IgG+ and IgA+ plasmablasts in the lamina propria, and Abs in intestinal fluid. On the contrary, complete tissue destruction and abscesses were seen in placebo recipients that succumbed to infection. Mice immunized as infants with YopB+dmLT or LcrV+dmLT achieved 60% protection against lethal Y. enterocolitica infection, and vaccine efficacy increased to 90-100% when they received YopB/LcrV+dmLT. YopB+dmLT also afforded substantial (60%) protection when administered intradermally to infant mice. YopB/LcrV+dmLT is a promising subunit vaccine candidate with the potential to elicit broad protection against Yersinia spp.

Pathogens transmitted in animal feces in low- and middle-income countries

Animals found in close proximity to humans in low-and middle-income countries (LMICs) harbor many pathogens capable of infecting humans, transmissible via their feces. Contact with animal feces poses a currently unquantified-though likely substantial-risk to human health. In LMIC settings, human exposure to animal feces may explain some of the limited success of recent water, sanitation, and hygiene interventions that have focused on limiting exposure to human excreta, with less attention to containing animal feces. We conducted a review to identify pathogens that may substantially contribute to the global burden of disease in humans through their spread in animal feces in the domestic environment in LMICs. Of the 65 potentially pathogenic organisms considered, 15 were deemed relevant, based on burden of disease and potential for zoonotic transmission. Of these, five were considered of highest concern based on a substantial burden of disease for which transmission in animal feces is potentially important: Campylobacter, non-typhoidal Salmonella (NTS), Lassa virus, Cryptosporidium, and Toxoplasma gondii. Most of these have a wide range of animal hosts, except Lassa virus, which is spread through the feces of rats indigenous to sub-Saharan Africa. Combined, these five pathogens cause close to one million deaths annually. More than half of these deaths are attributed to invasive NTS. We do not estimate an overall burden of disease from improperly managed animal feces in LMICs, because it is unknown what proportion of illnesses caused by these pathogens can be attributed to contact with animal feces. Typical water quantity, water quality, and handwashing interventions promoted in public health and development address transmission routes for both human and animal feces; however, sanitation interventions typically focus on containing human waste, often neglecting the residual burden of disease from pathogens transmitted via animal feces. This review compiles evidence on which pathogens may contribute to the burden of disease through transmission in animal feces; these data will help prioritize intervention types and regions that could most benefit from interventions aimed at reducing human contact with animal feces.

Campylobacteriosis, Salmonellosis, Yersiniosis, and Listeriosis as Zoonotic Foodborne Diseases: A Review

Zoonoses are diseases transmitted from animals to humans, posing a great threat to the health and life of people all over the world. According to WHO estimations, 600 million cases of diseases caused by contaminated food were noted in 2010, including almost 350 million caused by pathogenic bacteria. Campylobacter, Salmonella, as well as Yersinia enterocolitica and Listeria monocytogenes may dwell in livestock (poultry, cattle, and swine) but are also found in wild animals, pets, fish, and rodents. Animals, often being asymptomatic carriers of pathogens, excrete them with faeces, thus delivering them to the environment. Therefore, pathogens may invade new individuals, as well as reside on vegetables and fruits. Pathogenic bacteria also penetrate food production areas and may remain there in the form of a biofilm covering the surfaces of machines and equipment. A common occurrence of microbes in food products, as well as their improper or careless processing, leads to common poisonings. Symptoms of foodborne infections may be mild, sometimes flu-like, but they also may be accompanied by severe complications, some even fatal. The aim of the paper is to summarize and provide information on campylobacteriosis, salmonellosis, yersiniosis, and listeriosis and the aetiological factors of those diseases, along with the general characteristics of pathogens, virulence factors, and reservoirs.

Detection of Yersinia enterocolitica in Retail Chicken Meat, Mashhad, Iran

Poultry meat is one of the most important sources of infection of Yersinia spp. for humans. The aim of the present study was to evaluate the incidence of Yersinia enterocolitica in chicken meat by using culture method on selective medium and confirmation by PCR assay. Also, biochemical methods were used for biotyping. A total of 100 chicken thigh meat samples were collected randomly from retail outlets in Mashhad, Iran. Samples were enriched in Peptone-Sorbitol-Bile (PSB) broth and then cultured on Cefsulodin-Irgasan-Novobiocin (CIN) agar containing antibiotics supplement. The DNA was extracted from suspected colonies of Yersinia spp. and then PCR test using specific primers for 16S rRNA gene of Yersinia enterocolitica was performed. In this study, 30% of chicken meat was contaminated with Yersinia spp. by culture method and 25% of chicken meat was contaminated with Yersinia enterocolitica. Biotyping of isolated colonies showed that all of the isolates belonged to biotype 1A. Culture and detection of Yersinia spp. from food samples traditionally take 4 days. Due to high accuracy and speed of PCR assay, it is a good alternative method for microbiological techniques. In conclusion, poultry meat can act as a source of Y. enterocolitica and could be considered as a public health hazard.

Brotes de enfermedades transmitidas por los alimentos estudiados mediante técnicas moleculares

Objetivo Aplicar una técnica de reacción en cadena de la polimerasa (PCR) múltiple en tiempo real para la detección de Salmonella spp., Listeria monocytogenes y Yersinia enterocolitica, como herramienta de apoyo diagnóstico en la vigilancia de brotes de enfermedad transmitida por alimentos.Materiales y Métodos Se aplicó la metodología molecular en muestras clínicas provenientes de individuos que estaban asociados a brotes de enfermedad transmitida por alimentos de dos departamentos de Colombia. Los resultados se compararon con los datos arrojados por la metodología convencional de cultivo. Adicionalmente a los aislamientos obtenidos se les evaluó relación clonal mediante la técnica de electroforesis de campo pulsado (PFGE).Resultados Se determinó un total de 123 casos de enfermedad transmitida por alimentos de los cuales 45 muestras biológicas fueron confirmadas por laboratorio y 88 mediante nexo epidemiológico. La metodología molecular detectó 35/45 muestras positivas frente a 17/45 muestras positivas detectadas mediante la metodología convencional. La PFGE demostró relación clonal en cada brote.Conclusión Los resultados del estudio demuestran la aplicabilidad de la técnica molecular como herramienta útil de apoyo diagnóstico en la caracterización de brotes de enfermedad transmitida por alimentos, permitiendo una respuesta oportuna y confiable.

LuxCDE-luxAB-based promoter reporter system to monitor the Yersinia enterocolitica O:3 gene expression in vivo

It is crucial to understand the in vitro and in vivo regulation of the virulence factor genes of bacterial pathogens. In this study, we describe the construction of a versatile reporter system for Yersinia enterocolitica serotype O:3 (YeO3) based on the luxCDABE operon. In strain YeO3-luxCDE we integrated the luciferase substrate biosynthetic genes, luxCDE, into the genome of the bacterium so that the substrate is constitutively produced. The luxAB genes that encode the luciferase enzyme were cloned into a suicide vector to allow cloning of any promoter-containing fragment upstream the genes. When the obtained suicide-construct is mobilized into YeO3-luxCDE bacteria, it integrates into the recipient genome via homologous recombination between the cloned promoter fragment and the genomic promoter sequence and thereby generates a single-copy and stable promoter reporter. Lipopolysaccharide (LPS) O-antigen (O-ag) and outer core hexasaccharide (OC) of YeO3 are virulence factors necessary to colonization of the intestine and establishment of infection. To monitor the activities of the OC and O-ag gene cluster promoters we constructed the reporter strains YeO3-Poc::luxAB and YeO3-Pop1::luxAB, respectively. In vitro, at 37°C both promoter activities were highest during logarithmic growth and decreased when the bacteria entered stationary growth phase. At 22°C the OC gene cluster promoter activity increased during the late logarithmic phase. Both promoters were more active in late stationary phase. To monitor the promoter activities in vivo, mice were infected intragastrically and the reporter activities monitored by the IVIS technology. The mouse experiments revealed that both LPS promoters were well expressed in vivo and could be detected by IVIS, mainly from the intestinal region of orally infected mice.

Presence of ail and ystB genes in Yersinia enterocolitica biotype 1A isolates from game animals in Poland

The pathogenicity of Yersinia enterocolitica is associated with the presence of plasmid and chromosomal virulence genes. Strains belonging to biotype 1A do not possess pYV plasmids, often harbour the ystB gene and usually lack the ail gene, which is the main virulence marker for Y. enterocolitica. The simultaneous presence of ail and ystB is uncommon. In this study, 21/218 (9.6%) biotype 1A Y. enterocolitica isolates from rectal swabs of wild boar (Sus scrofa; n = 18), red deer (Cervus elaphus; n = 2) and roe deer (Capreolus capreolus; n = 1) in Poland harboured both ail and ystB genes.

Detection of pathogenic Yersinia enterocolitica in pet Djungarian hamsters in Japan

The prevalence of Yersinia enterocolitica (Y. enterocolitica) and Yersinia pseudotuberculosis was examined in 151 pet animals including 108 rodents, 39 rabbits and four sugar gliders from 13 pet stores in the Yamaguchi Prefecture, Japan. Y. enterocolitica serogroup O:3 biotype 3 negative for the Voges-Proskauer reaction (O:3/3 variant VP-) was isolated from five Djungarian hamsters (Phodopus sungorus) raised at the same pet store. These pathogenic Y. enterocolitica isolates carried the virulence genes, yadA, ail and virF, and were shown to be clonal by pulsed-field gel electrophoresis with NotI digestion. This is a first report of pathogenic Y. enterocolitica O:3/3 variant VP- in pet Djungarian hamsters in Japan.

[Two Outbreaks of Yersinia enterocolitica O:8 Infections in Tokyo and the Characterization of Isolates]

Although the number of outbreaks caused by Yersinia enterocolitica has been very small in Japan, 4 outbreaks were occurred during the 2 years between 2012 and 2013. We describe herein 2 outbreaks which were examined in Tokyo in the present study. Outbreak 1: A total of 39 people (37 high school students and 2 staff) stayed at a hotel in mountain area in Japan had experienced abdominal pain, diarrhea and fever in August, 2012. The Y. enterocolitica serogroup O:8 was isolated from 18 (64.3%) out of 28 fecal specimens of 28 patients. The infection roots could not be revealed because Y. enterocolitica was not detected from any meals at the hotel or its environment. Outbreak 2: A total of 52 students at a dormitory had diarrhea and fever in April, 2013. The results of the bacteriological and virological examinations of fecal specimens of patients showed that the Y. enterocolitica serogroup O:8 was isolated from 24 fecal specimens of 21 patients and 3 kitchen staff. We performed bacteriological and virological examination of the stored and preserved foods at the kitchen of the dormitory to reveal the suspect food. For the detection of Y. enterocolitica, food samples. together with phosphate buffered saline (PBS) were incubated at 4 degrees C for 21 days. Then, a screening test for Y. enterocolitica using realtime-PCR targeting the ail gene was performed against the PBS culture. One sample (fresh vegetable salad) tested was positive on realtime-PCR. No Y. enterocolitica was isolated on CIN agar from the PBS culture because many bacteria colonies other than Y. enterocolitica appeared on the CIN agar. After the alkaline-treatments of the culture broth or the immunomagnetic beads concentration method using anti-Y. enterocolitica O:8 antibodies, Y. enterocolitica O:8 which was the same serogroup as the patients' isolates was successfully isolated from the PBS culture. The fresh vegetable salad was confirmed as the incrimination food of this outbreak.

Environmentally Transmitted Pathogens

This chapter describes a variety of pathogens found in the environment that are capable of infecting humans and causing disease. Different classes of pathogens are discussed including bacteria, parasites and viruses. For each pathogen, data are provided on the incidence of the organism in a particular environmental matrix such as water, food or municipal waste. In addition, we discuss: the disease caused by the particular microbe; the mode of transmission; the incubation time needed within the host prior to the onset of disease; and the duration of illness. Fate and transport of pathogens in the environment are also described. A variety of bacterial pathogens are discussed including waterborne and waterbased bacteria. Parasites discussed include protozoa, nematodes, cestodes and trematodes. For viruses, both enteric and respiratory viruses are included.

Detection and Characterization of Shiga Toxin Producing Escherichia coli, Salmonella spp., and Yersinia Strains from Human, Animal, and Food Samples in San Luis, Argentina

Shiga toxin producing Escherichia coli (STEC), Salmonella spp., and Yersinia species was investigated in humans, animals, and foods in San Luis, Argentina. A total of 453 samples were analyzed by culture and PCR. The antimicrobial susceptibility of all the strains was studied, the genomic relationships among isolates of the same species were determined by PFGE, and the potencial virulence of Y. enterocolitica strains was analyzed. Yersinia species showed higher prevalence (9/453, 2.0%, 95% CI, 0.7–3.3%) than STEC (4/453, 0.9%, 95% CI, 0–1.8%) and Salmonella spp. (3/453, 0.7%, 95% CI, 0–1.5%). Y. enterocolitica and Y. intermedia were isolated from chicken carcasses (6/80, 7.5%, 95% CI, 1.5–13.5%) and porcine skin and bones (3/10, 30%, 95% CI, 0–65%). One STEC strain was recovered from human feces (1/70, 1.4%, 95% CI, 0–4.2%) and STEC stx1/stx2 genes were detected in bovine stools (3/129, 2.3%, 95% CI, 0–5.0%). S. Typhimurium was isolated from human feces (1/70, 1.4%, 95% CI, 0–4.2%) while one S. Newport and two S. Gaminara strains were recovered from one wild boar (1/3, 33%, 95% CI, 0–99%). The knowledge of prevalence and characteristics of these enteropathogens in our region would allow public health services to take adequate preventive measures.

Unique activity spectrum of colicin FY: all 110 characterized Yersinia enterocolitica isolates were colicin FY susceptible

Colicin FY is a plasmid encoded toxin that recognizes a yersinia-specific outer membrane protein (YiuR) as a receptor molecule. We have previously shown that the activity spectrum of colicin FY comprises strains of the genus Yersinia. In this study, we analyzed the activity of colicin FY against 110 Yersinia enterocolitica isolates differing in geographical origin and source. All isolates were characterized through analysis of 16S rRNA genes, serotyping, biotyping, restriction profiling of genomic DNA, detection of virulence markers and susceptibility to antibiotics. This confirmed the broad variability of the collection, in which all 110 Y. enterocolitica isolates, representing 77 various strains, were inhibited by colicin FY. Although isolates showed variable levels of susceptibility to colicin FY, it was not associated with any strain characteristic. The universal susceptibility of Y. enterocolitica strains to colicin FY together with the absence of activity towards strains outside the Yersinia genus suggests potential therapeutic applications for colicin FY.

Persistent bloody diarrhoea without fever associated with diffusely adherent Escherichia coli in a young child

Diffusely adherent Escherichia coli (DAEC) is thought to cause diarrhoea in children, and so too are other diarrhoeagenic E. coli (DEC); however, the evidence base is inconclusive. DEC pathotypes are differentiated on the basis of their pathogenic features, and thus cannot be quickly identified on selective culture media. Molecular techniques, not readily available in most clinical laboratories, are required to differentiate DEC strains from non-pathogenic E. coli in the stool flora. We report a case of persistent bloody diarrhoea, without fever, in a previously healthy 21-month infant from whom we isolated five DAEC strains. The child’s stools movements were loose, with gross blood and mucus; fresh mount analysis revealed numerous faecal leukocytes and erythrocytes. Response to antimicrobial treatment with trimethoprim-sulfamethoxazole was poor despite susceptibility in vitro. Although the patient improved with azithromycin, blood was present in the patient’s stools for over 30 days. The severe diarrhoea in this patient might be explained by the fact that these DAEC isolates harboured a siderophore receptor, which allows the bacteria to use iron derived from haem compounds that promote its multiplication. The isolates also induced in vitro secretion of several immunomodulatory cytokines that may account for the patient’s loose stools and faecal leukocytes. DAEC may play a greater role than suspected in afebrile children with bloody diarrhoea.

Yersinia enterocoliticainfections associated with improperly pasteurized milk products: southwest Pennsylvania, March–August, 2011

In July 2011, a cluster ofYersinia enterocoliticainfections was detected in southwestern Pennsylvania, USA. We investigated the outbreak's source and scope in order to prevent further transmission. Twenty-two persons were diagnosed with yersiniosis; 16 of whom reported consuming pasteurized dairy products from dairy A. Pasteurized milk and food samples were collected from this dairy.Y. enterocoliticawas isolated from two products. Isolates from both food samples and available clinical isolates from nine dairy A consumers were indistinguishable by pulsed-field gel electrophoresis. Environmental and microbiological investigations were performed at dairy A and pasteurization deficiencies were noted. Because consumption of pasteurized milk is common and outbreaks have the potential to become large, public health interventions such as consumer advisories or closure of the dairy must be implemented quickly to prevent additional cases if epidemiological or laboratory evidence implicates pasteurized milk as the outbreak source.