Enterocolitica Contamination Research Articles

Traceability, virulence and antimicrobial resistance of Yersinia enterocolitica in two industrial cheese-making plants

Between 2018 and 2019, 309 environmental and food samples were collected from two industrial cheese-making plants located in Sardinia, in order to investigate Y. enterocolitica presence and to characterize the isolates. Y. enterocolitica isolates were further compared with isolates detected during a previous investigation from sheep and goat raw milk samples. Y. enterocolitica was detected in 7.4 % of the samples and the prevalence was higher, even if not significantly (P > 0.05) higher in non-food contact surface samples (10.2 %) than in food contact surface samples (3.8 %). The highest prevalence was detected in floor samples (13.5 %), followed by drain samples (7.2 %), which might serve as main harborage sites for further contamination. Y. enterocolitica was also detected in food contact surfaces, namely shelves of the Ricotta cooling room and packaging room, one cheese cutting machine surface and one raw milk filter sample. The biotype 1A isolates identified in this study were classified into six different serotypes. Additionally, a bioserotype 2/O:5,27 isolate was identified in one goat milk sample. All 1A isolates possessed the virulence genes invA and ystB while the 2/O:5,27 isolate showed the presence of ail, ystA, invA and yadA genes, thus confirming a pathogenic potential. The isolates showed intrinsic resistance to amoxicillin-clavulanic acid, ticarcillin and cefoxitin due to the presence of the blaA gene. Whole genome sequencing allowed to identify seven different sequence types among the 1A isolates, thus showing a high genetic diversity. The same Y. enterocolitica sequence type (ST3) was detected from three different areas of the same cheese-making plant, indicating a possible transfer of the microorganism along the processing lines. Y. enterocolitica contamination in cheese-making plants can pose a risk to human health. Preventive measures include the hygienic design of the plant layout and equipment, in association with proper cleaning and disinfection programmes.

Comparison of inactivation kinetics of Yersinia enterocolitica in vegan and non-vegan kimchi during fermentation

Yersinia enterocolitica is occasionally detected in kimchi, a traditional food prepared from fermented vegetables. Changes in growth properties of Y. enterocolitica during kimchi fermentation are largely unknown. We investigated the viability of Y. enterocolitica during the fermentation of vegan and non-vegan kimchi at different temperatures. Changes in Y. enterocolitica population, pH, and titratable acidity were measured for 24 days. In a suspension test with kimchi juice, populations of three Y. enterocolitica strains were above 3.30 log10 CFU/mL at pH > 5 for 7 days. Yersinia enterocolitica counts in vegan kimchi were considerably reduced at 0 °C and 6 °C. During fermentation at 6 °C, Y. enterocolitica populations in non-vegan kimchi and vegan kimchi were not detected starting from days 14 and 10, respectively. In kimchi samples stored at 0 °C and 6 °C, Y. enterocolitica survival correlated with pH changes during fermentation; in samples stored for up to 24 days, Y. enterocolitica was not detected. According to the kmax values from the “log-linear with shoulder and tail” model, Y. enterocolitica was more sensitive to vegan kimchi fermentation than to non-vegan kimchi fermentation. Our findings provide an important basis for ensuring the safe production of kimchi without Y. enterocolitica contamination. Further research is necessary to elucidate the mechanism of Y. enterocolitica inactivation and the major bacterial and physicochemical factors involved in kimchi fermentation.

Inhibitory effect of protocatechualdehyde on Yersinia enterocolitica and its critical virulence factors

Yersinia enterocolitica (Y. enterocolitica) is a gastrointestinal pathogen that is distributed worldwide, involved in systemic, extraintestinal and invasive infections in immunocompromised patients. Establishment of antibiotic resistance in the pathogen has produced a need for new antibacterial agents. The purpose of this study was to elucidate antibacterial mechanism of protocatechualdehyde (PCA) extracted from the roots of Salvia miltiorrhiza towards Y. enterocolitica, and to investigate effects of PCA on key virulence factors associated with human infection. Present results indicated that PCA exerted its antibacterial activity against Y. enterocolitica mainly by the rapid rise of intracellular reactive oxygen species, leading to change in permeability and integrity of cell membrane, and ultimately decline of membrane potential and intracellular ATP. Furthermore, scanning electron microscopic analysis revealed that Y. enterocolitica presented gradually shrinkage in length and partial wrinkles upon PCA treatment. PCA also effectively decreased motility, biofilm formation, quorum sensing in a dose-dependent manner without affecting bacterial growth. Further, at SICs, PCA substantially suppressed the adhesion and invasion of Y. enterocolitica to HT-29 cells and the downregulation of essential virulence factor-encoding genes unveiled impaired virulence. Overall, the findings revealed the potential of PCA as an alternative antibacterial agent to combat Y. enterocolitica contamination and infections.

Antibacterial mechanism of Protocatechuic acid against Yersinia enterocolitica and its application in pork

Protocatechuic acid (PCA) has adequate antibacterial activity against foodborne pathogens; however, its antibacterial mechanism has been rarely investigated. Therefore, this study attempts to elucidate the antibacterial mechanism of PCA against Yersinia enterocolitica . The corresponding results showed that PCA had a satisfactory antibacterial effect on Y. enterocolitica with a minimum inhibitory concentration (MIC) of 2.5 mg/mL. Accordingly, depolarization of the cell membrane, reduction of intracellular pH (pH in ) and adenosine triphosphate (ATP), leakage of K + and destruction of cell morphology were observed in this study, which indicated that PCA changed the membrane permeability of Y. enterocolitica . According to the metabolomics analysis, PCA induced the differential expression of the metabolites of Y. enterocolitica . In addition, enrichment analysis of metabolic pathways demonstrated that PCA disordered energy metabolism and amino acid biosynthesis of Y. enterocolitica . PCA also exhibited a notable inhibitory effect on Y. enterocolitica in pork. According to the corresponding findings, PCA may possess potential antibacterial properties in controlling Y. enterocolitica contamination within food industry. • Protocatechuic acid showed high antibacterial activity against Y. enterocolitica. • Protocatechuic acid destroyed the cell membrane structure of Y. enterocolitica. • Protocatechuic acid disordered energy metabolism and amino acid metabolism. • Protocatechuic acid extended the shelf life of chilled pork.

Study of Yersinia enterocolitica contamination in red meat supplied In Shiraz, Iran

Yersinia enterocolitica is one of the intestinal pathogens that are transferred to human through water and food, especially infected meat. Food contamination with this bacterium causes diarrhea, vomiting, stomach pain, appendicitis syndrome, like fever and septicemia. This study aimed study the red meat supplied in Shiraz for Yersinia enterocolitica contamination. In this study, 200 samples of meat supplied in Shiraz were prepared, and were classified based on packaging and non-packaging, storage method and retention time of cart and were investigated for Yersinia enterocolitica contamination. Samples were transferred to PBS enriched environment containing sorbitol sugar and bile salts. These samples were stored in a refrigerator at 4°C for three weeks and then cultured on selected culture medium of Yersinia enterocolitica. Then, microbiological and biochemical subtraction tests were performed on samples. According to study, 13% of the collect meat samples (26 samples) was infected with Yersinia enterocolitica. The results showed no significant difference in the frequency of contamination among different groups of the samples. The studies show that a significant amount of red meat can be contaminated with bacteria when meat foods are not heated enough during cooking, and subsequent storage in the refrigerator provides the opportunity to amplification of this bacterium. Moreover, due to the lack of apparent signs of spoilage, this bacterium causes gastroenteritis and other gastrointestinal complications in consumers.

Development of IMBs-qPCR detection method for Yersinia enterocolitica based on the foxA gene.

Yersinia enterocolitica is an important zoonotic pathogen, which seriously endangers food-safety risk. In this study, the recombinant outer membrane protein OmpF and its antibody were prepared and coupled with immunomagnetic beads (IMBs) to capture Y. enterocolitica in food samples, combining the quantitative PCR detection with primers of virulence factor gene foxA for Yersinia enterocolitica contamination. The results showed that the capture efficiency of approximately 80% using anti-OmpF antibody-immunomagnetic beads and linearly dependent capture under 101-105CFU/mL Y. enterocolitica compared with less than 10% capture of other bacteria. The detection limit of 64CFU/mL was obtained based on foxA gene PCR detection combined with capture of the anti-OmpF antibody-immunomagnetic beads to detect Yersinia enterocolitica in artificially contaminated milk and pork samples. Compared to the culture method, the developed IMBs-qPCR method has higher consistency, was less time consuming, which taken together provides an effective alternative method for rapid detection of Y. enterocolitica in food.

Survival of Yersinia enterocolitica in Yogurt and Ice-cream

In this study yogurt was inoculated with Y. enterocolitica strain during its manufacture, then part stored at refrigerated temperature and the other part stored at room temperature. Acidity % and pH were measured as well as enumeration of Yersinia. Results showed that Y. enterocolitica could be detected in refrigerated stored yogurt but not in yogurt stored at room temperature by the end of the week. The same strain was inoculated during manufacture of vanilla as well as lemon flavor ice-cream and enumeration of the microorganism was done for 2 months. Results revealed that Y. enterocolitica survived in vanilla ice-cream but can’t survive in lemon flavor ice-cream for 2 months. It was concluded that strict hygienic measures must be applied to prevent infections associated with Y. enterocolitica contamination.

Prevalence, antimicrobial resistance and phylogenetic characterization of Yersinia enterocolitica in retail poultry meat and swine feces in parts of China

Yersinia enterocolitica is an enteropathogen transmitted by contaminated food. In this study, a total of 500 retail poultry meat samples from 4 provinces and 145 swine feces samples from 12 provinces in China was tested for Y. enterocolitica and 26 isolates were obtained for further bio-serotyping, testing with antimicrobial susceptibility testing to a panel of antimicrobial compounds, and genetically characterization based on the whole genome sequencing. Higher prevalence (4.8%) of Y. enterocolitica contamination in retail poultry meat than that in swine feces (2.76%) was observed. No difference in bio-serotypes, multilocus sequence typing (MLST) and virulence genes distribution between swine and poultry origin were found. All isolates were resistant to ampicillin, amoxicillin/clavulanic acid, and cefazolin and were multi-drug resistant (MDR). The most predominant drug-resistance profile was AMP-CFZ-AMC-FOX (42.31%). A pathogenic isolate with bio-serotype 3/O:3 and ST135 was cultured from retail fresh chicken meat for the first time in China. Based on the whole-genome single nucleotide polymorphisms (SNPs) tree analysis, pathogenic isolates clustered closely, while nonpathogenic isolates exhibited high genetic heterogeneity. These indicated that pathogenic isolates were conserved on genetic level. The whole-genome SNP tree also revealed that Y. enterocolitica of swine, chicken and duck origin may share a common ancestor. The findings highlight the emergence of drug-resistant pathogenic Y. entrocoliticas in retailed poultry meats in China.

Yersinia enterocolitica in a Brazilian pork production chain: Tracking of contamination routes, virulence and antimicrobial resistance

This study aimed to track Yersinia enterocolitica contamination in a pork production chain in Minas Gerais, Brazil, and to characterize the virulence and antibiotic resistance of isolates. Samples were collected from four different steps of the pork production chain (pig farm, carcass, processing environment and end product; n = 870), and tested for the presence of Y. enterocolitica. The pathogen was detected in 8 samples (palatine tonsils = 5; mesenteric lymph nodes = 2; carcass after bleeding = 1), from which 16 isolates were obtained and identified as Y. enterocolitica bioserotype 4/O:3. XbaI macrorestriction allowed the clustering of isolates in 5 pulsetypes, and the identification of identical profiles of Y. enterocolitca isolated from different samples. All isolates were positive for the virulence related genes ail, virF, myfA, ystA, tccC, ymoA, hreP and sat, and negative for ystB, ystC, fepA, fepD and fes. Considering 17 antibiotics from 11 classes, only ciprofloxacin and kanamycin were effective against all isolates, and three multidrug resistance profiles were identified among them, with simultaneous resistance to 9 of 11 classes. All isolates presented positive results for emrD, yfhD and marC, related to multidrug resistance. The results of this study demonstrated the contamination routes of Y. enterocolitica within the assessed pork production chain, and highlighted the pathogenic potential and antibiotic resistance of this foodborne pathogen.

Bacteriophages reduce Yersinia enterocolitica contamination of food and kitchenware

Yersinia enterocolitica, the primary cause of yersiniosis, is one of the most important foodborne pathogens globally and is associated with the consumption of raw contaminated pork. In the current study, four virulent bacteriophages (phages), one of Podoviridae (fHe-Yen3-01) and three of Myoviridae (fHe-Yen9-01, fHe-Yen9-02, and fHe-Yen9-03), capable of infecting Y. enterocolitica were isolated and characterized. fHe-Yen9-01 had the broadest host range (61.3% of strains, 65/106). It demonstrated a latent period of 35 min and a burst size of 33 plaque-forming units/cell, and was found to have a genome of 167,773 bp with 34.79% GC content. To evaluate the effectiveness of phage fHe-Yen9-01 against Y. enterocolitica O:9 strain Ruokola/71, we designed an experimental model of the food market environment. Phage treatment after bacterial inoculation of food samples, including raw pork (4 °C, 72 h), ready-to-eat pork (26 °C, 12 h), and milk (4 °C, 72 h), prevented bacterial growth throughout the experiments, with counts decreasing by 1–3 logs from the original levels of 2–4 × 103 CFU/g or ml. Similarly, when artificially contaminated kitchen utensils, such as wooden and plastic cutting boards and knives, and artificial hands, were treated with phages for 2 h, bacterial growth was effectively inhibited, with counts decreasing by 1–2 logs from the original levels of ca 104 CFU/cm2 or ml. To the best of our knowledge, this is the first report of the successful application of phages for the control of Y. enterocolitica growth in food and on kitchen utensils.

ЧУТЛИВІСТЬ ЗБУДНИКА КИШКОВОГО ІЄРСИНІОЗУ ДО ДЕЗІНФЕКТАНТІВ

The article presents the results of a study of the inactivating action of modern disinfectants pathogen intestinal yersiniosis. Determine the sensitivity of the laboratory and field strains of Yersinia enterocolitica to drugs «Virosan» and «Biokontakt». Preparations intended for preventive disinfection of livestock buildings and facilities subject to veterinary supervision, items of artificial insemination, filling dezbarerov, as well as for disinfection of transport, processing of hatching eggs. As a result, three–time experiments conducted in similar conditions found that the drugs «Virosan» and «Biokontakt» are effective disinfectants in the case of pathogen Yersinia enterocolitica contamination of various objects (concrete, brick, wood and tile, metal). The studies found effective concentrations mentioned disinfectants and the exposure determined under what strains of Y. enterocolitica is completely inactivated. It was established that the preparation «Virosan» at a concentration of 0.1% has a bactericidal effect at 30 minutes, at a concentration of 0.2–0.5% – within 15 minutes. It is also found that the disinfectant «Biokontakt» ensures complete killing Y. enterocolitica in all test sites at a concentration of 0.01% within 30 minutes, at a concentration of 0.1 – 0.5% – bactericidal effects is apparent within 15 min. Differences in their antibacterial action on laboratory and field strains of the pathogen were observed.

Prevalence, antimicrobial resistance and genetic diversity of Yersinia enterocolitica isolated from retail frozen foods in China.

In this study, our aim was to estimate the extent of Yersinia enterocolitica contamination in frozen foods in China and determine the bioserotype, virulotype, antimicrobial resistance, and enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) genotyping profiles of recovered Y. enterocolitica isolates. Out of 455 samples collected between July 2011 and May 2014, 56 (12.3%) tested positive for Y. enterocolitica. The 70 isolated strains were grouped into five clusters and one singleton based on their ERIC-PCR fingerprint, at a similarity coefficient of 70%. All strains were of biotype 1A, and 35.7% were of bioserotype 1A/O:8. Most strains lacked the virulence genes ail, virF, ystA, and ystC, but harbored ystB, fepD, ymoA, fes and sat. All strains were sensitive to ticarcillin but resistant to two or more antibiotics, and 48.6% of the strains were resistant to four to nine antibiotics. High resistance rates were observed for ampicillin, cephalothin, trimethoprim/sulfamethoxazole, amoxicillin/clavulanic acid, nalidixic acid and chloramphenicol (98.6%, 95.7%, 74.3%, 28.6%, 18.6% and 12.9%, respectively). This study provides a systematic surveillance of Y. enterocolitica prevalence in frozen foods in China and indicates its high antibiotic resistance, which could serve as useful information for the government to control Y. enterocolitica contamination in frozen foods and the use of antibiotics.

Bayesian modelling to identify the risk factors for Yersinia enterocolitica contamination of pork carcasses and pluck sets in slaughterhouses

The probability of contamination by pathogenic Yersinia enterocolitica of carcasses and pluck sets at slaughterhouse was determined by means of a Bayesian analysis. Prior information of the prevalence of Y. enterocolitica in faeces and the seroprevalence of Yersinia in serum of pigs collected at farms were obtained from previous studies and introduced in the models as beta prior informative distributions. Samples of intestinal content, tonsils, and swabs of carcasses and pluck set surfaces were collected at slaughterhouses. The posterior probabilities, odds ratio (OR) and their probability interval (PI) were calculated by means of a generalized linear model constructed in WinBugs. Occurrence of Y. enterocolitica in intestinal content (OR: 35.6, 95%PI 2.8–8285), tonsils (OR: 38.4, 95%PI 5.0–854), and pluck set (OR: 16.6, 95%PI 1.9–1111) was a risk for the contamination of pork carcasses, and an increased risk of contaminated pluck set was observed when Y. enterocolitica was isolated in intestinal content (OR: 40.6, 95%PI 2.1–10510) and tonsils (OR: 17.6, 95%PI 3.4–230.6). This increased risk indicated a potential cross-contamination at the slaughterhouse.

THE ROLE OF PIGS AS PHARYNGEAL CARRIERS OF HUMAN PATHOGENIC YERSINIA ENTEROCOLITICA STRAINS

From March 2007 to January 2008, a total of 170 pigs at slaughter were tested for Y. enterocolitica contamination in tonsils tissue. The animals came from 125 different farms located in four regions of Northern Italy. Y. enterocolitica was isolated from 19 out of 170 (11.2%) tonsils samples. The prevalent bio-serotype (68.4%) was 4/O:3, followed by bioserotypes 1A/O:8 (15.8%), 1A/O:5 (10.5%) and 4/O:8 (5.2%). Among bio-serotype 4/O:3, several strains possessed yadA, ail and ystA virulence genes.

Inhibitory effects of sucrose fatty acid esters on survival ofYersinia enterocoliticaon eggshell surface and use of blue lake as indicator of bacterial penetration into eggs

To determine the effectiveness of sucrose monolaurate (SML) and sucrose monocaprate (SMC), alone and in combination with ethylenediaminetetraacetic acid (EDTA), propionic acid (PA) or citric acid (CA) in reducing mesophilic aerobic bacteria (MAB) and Yersinia enterocolitica O:9 populations on eggshells and their damage potential on the microstructure of shell cuticle. Uninoculated eggs and eggs submerged in a solution of Y. enterocolitica were immersed in solutions of the various treatments. MAB and Y. enterocolitica counts on the surface of the eggs were carried out before and after treatment. MAB counts decreased less than 2 logs on uninoculated eggshells irrespective of treatment and reductions of 3.2 and 3.0 logs of Y. enterocolitica were obtained with 1000 microg ml(-1) SML plus 0.1% CA or 1000 microg ml(-1) SML plus 600 microg ml(-1) EDTA solutions, respectively. Y. enterocolitica 2/O:9 was recovered from natural microflora. Use of blue lake staining revealed minimal damage to the shells from the washing treatments. SML and SMC at 1000 microg ml(-1) combined with CA or EDTA could be effective in reducing Y. enterocolitica on eggshells with a minimal risk of later bacterial recontamination. Eggs are a recognized vehicle for transmission of Y enterocolitica although a prevalence of only 2.7% was detected in this study. Washing eggs in solutions containing SML or SMC could eliminate Y. enterocolitica contamination of egg shells.

Validation of a method for the detection of virulent Yersinia enterocolitica and their distribution in slaughter pigs from conventional and alternative housing systems

Various methods have been described in the literature for the detection of virulent Yersinia enterocolitica in pigs. The risk factors for pig herd contamination have yet to be determined. The objective of this study was to validate a sensitive method for the detection of Y. enterocolitica and to describe the distribution of the bacteria in pigs at slaughter from conventional and alternative (“organic”) housing systems. First, samples were collected from tonsils, caecum with caecal contents, and the caecal lymph nodes of 60 slaughter pigs. These samples were used to compare the sensitivity of six different laboratory culture methods either in common use or described in the literature with that of a polymerase chain reaction with two primer pairs (multiplex PCR). Then, only PCR was used to examine tonsils, caecum and caecal lymph nodes from two groups of slaughter pigs: 210 from six conventional fattening farms and 200 from three with alternative housing. The results of the multiplex PCR were positive in 28 cases. All culture methods proved inferior to PCR in sensitivity. In the second part of the study, PCR detected 36 (18%) positive pigs from alternative housing and 60 (29%) from conventional housing ( p < 0.05). The highest rate of Y. enterocolitica contamination was found in tonsils (11% alternative, 22% conventional; p < 0.05), followed by caecum (5%, 11%) and lymph nodes (2%, 7%). The housing system appears to be one important factor in the prevalence of this common pathogen in pig herds, as we found important differences between the two systems studied here. In the conventional system, the main risk factors appeared to be sourcing pigs from different pig suppliers, use of commercial feed and transportation to slaughter.

Contamination of Carcasses, Offals, and the Environment with yadA-Positive Yersinia enterocolitica in a Pig Slaughterhouse

This study was carried out in order to evaluate the contamination of the pig-slaughtering line with pathogenic Yersinia enterocolitica carrying the yadA gene. A total of 292 samples were collected from the slaughterhouse; 131 swab samples from pig carcasses, ears, livers, kidneys, and hearts; 89 swab samples from the environment; and 72 sedimentation samples from the air. All surface samples were studied with both the polymerase chain reaction (PCR) and culture methods. The contamination rate of edible pig offals was high with both methods. Using PCR, the detection rates of yadA-positive Y. enterocolitica for livers, kidneys, and hearts were 38, 86, and 63%, respectively, and using the culture method, the detection rates were 31, 69, and 50%, respectively. Pathogenic Y. enterocolitica was also detected from different environmental sites in the slaughterhouse. Using PCR, 13% of the surface samples from the environment were contaminated with yadA-positive Y. enterocolitica. PCR-positive samples were found on the brisket saw, the hook from which the pluck set (heart, lungs, esophagus, trachea, diaphragm, liver, kidneys, and tongue with tonsils) hang, the knife used for evisceration, the floors in the eviscerating area and the weighing area, the meat-cutting table, the aprons used by trimming workers, the computer used in the meat-inspection area, and the coffeemaker used by slaughterhouse workers. The respective detection rate (6%) was considerably lower when we used the culture method. Pathogenic Y. enterocolitica was isolated from the air in the bleeding area. Bioserotype 4/O:3 was the only pathogenic bioserotype isolated in this study. A total of 113 isolates of type 4/O:3 were characterized with pulsed-field gel electrophoresis using NotI and XbaI digests. By combining these profiles, nine different pulsotypes were obtained, the most common of which (1a) was found in 19 (61%) of 31 samples from different sites. This is the same type that has dominated in pig tonsils, which suggests that tonsils may be the source of Y. enterocolitica contamination in the slaughterhouse. The four pulsotypes (1a, 4g, 6g, and 19q) found on edible offals were the same as those found in tonsils, which supports our hypothesis that tonsils are the contamination source for the liver, heart, and kidneys.

Modeling the growth of Yersinia enterocolitica in donated blood.

Sepsis and death subsequent to the transfusion of blood containing Yersinia enterocolitica is an increasing problem. The organisms probably originate from bacteremia in the donor and can subsequently multiply at low temperature. Reported here are experiments with a strain of Y. enterocolitica associated with a case of transfusion-associated bacteremia. It was found that the rapid early killing of Y. enterocolitica injected into donated blood does not require viable phagocytes and can be explained by complement-mediated killing. Complement resistance in Y. enterocolitica is known to be plasmid-coded. It is expressed at 37 degrees C, but not at 20 degrees C, and is favored by calcium-deficient culture media. Y. enterocolitica organisms induced to express complement resistance were still killed in donated blood, though the initial rate was slower. Such organisms multiplied in plasma at 37 degrees C, but were killed after 6 hours of incubation at 20 degrees C, presumably because complement resistance genes are switched off at this temperature. This experiment is thought to reflect the natural history of Y. enterocolitica contamination of blood, in which complement-resistant organisms in the donor blood encounter lower temperatures after donation. These observations suggest that the practice of plasma depletion may have contributed to the increased incidence of mortality due to Y. enterocolitica contamination of donated blood.

Yersinia pathogenicity factors.

Among the many species of the Yersinia genus, only Y. pestis, Y. pseudotuberculosis and Y. enterocolitica are adapted to multiply at the expense of a host that is still alive. Y. pestis, the agent of plague, and Y. pseudotuberculosis are essentially rodent pathogens. Y. enterocolitica is a common human pathogen which causes gastrointestinal syndromes of varying severities, ranging from mild self-limited diarrhea to mesenteric adenitis evoking an appendicitis. Systemic involvement is unusual with Y. enterocolitica but reactive arthritis and erythema nodosum are common complications (COVER and ABER 1989) . In Europe, pork is a current source of Y. enterocolitica contamination (TAUXE et al. 1987).KeywordsOuter Membrane ProteinYersinia EnterocoliticaShigella FlexneriXanthomonas CampestrisYersinia PestisThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Direct identification of Yersinia enterocolitica in blood by polymerase chain reaction amplification

Primers based on the nucleotide sequence of the virF gene in the pYV plasmid and the chromosomal ail gene were used in polymerase chain reaction (PCR) amplifications to directly identify Yersinia enterocolitica in blood. Approximately 500 bacteria seeded into 100 microL of blood can be extracted and amplified by PCR to yield positive results. PCR analyses of seven Y. enterocolitica isolates previously implicated in blood contaminations showed that only one isolate harbored the plasmid-borne virF gene; however, all seven isolates were identified effectively by the PCR product amplified from the chromosomal gene. The PCR assay has the potential for use in the identification of Y. enterocolitica contamination in stored units of blood or in the rapid diagnosis of transfusion-related bacteremia caused by Y.