Prevalence Of Pathogenic Yersinia Enterocolitica Research Articles

Prevalence, Genetic Homogeneity, and Antibiotic Resistance of Pathogenic Yersinia enterocolitica Strains Isolated from Slaughtered Pigs in Bulgaria.

Yersiniosis is the third most commonly reported foodborne zoonosis in the European Union. Here, we evaluated the prevalence of pathogenic Yersinia enterocolitica among healthy pigs (as a major reservoir) in a slaughterhouse in Bulgaria. A total of 790 tonsils and feces from 601 pigs were examined. Isolation and pathogenicity characterization was carried out by the ISO 10273:2003 protocol and Polymerase Chain Reaction (PCR), detecting the 16S rRNA gene, attachment and invasion locus (ail), Yersinia heat-stable enterotoxin (ystA), and Yersinia adhesion (yadA) genes. Genetic diversity was assessed by pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance by the standard disk diffusion method. Of all the pigs tested, 6.7% were positive for Y. enterocolitica. All isolates belonged to Y. enterocolitica bioserotype 4/O:3. ail, and ystA genes were detected in all positive strains (n = 43), while the plasmid Yersinia virulence plasmid (pYV) was detected in 41. High homogeneity was observed among the strains, with all strains susceptible to ceftriaxone, amikacin and ciprofloxacin, and resistant to ampicillin. In conclusion, a low prevalence of Y. enterocolitica 4/O:3 was found in healthy pigs slaughtered in Bulgaria, not underestimating possible contamination of pork as a potential risk to consumer health.

Isolation and identification of Yersinia enterocolitica in bovine milk samples of bulk tanks from dairy farms in São Paulo, Brazil

Milk and its derivatives are good substrates for the proliferation of pathogenic and quality-deteriorating microorganisms, demanding rigorous care with milking, processing, and storage. Among the various bacteria that can grow in raw refrigerated milk, Yersinia enterocolitica, is an invasive enteropathogen of humans. This bacterium can cause a number of intestinal and extraintestinal clinical symptoms, ranging from mild gastroenteritis to mesenteric lymphadenitis, similar to appendicitis. To evaluate the prevalence of pathogenic Yersinia enterocolitica in raw milk from bulk milk tanks located in the State of São Paulo, 102 bovine milk samples (one per dairy farm) were evaluated by microbiological analyses, followed by biochemical tests PCR and genetic sequencing. Microbiological testing did not isolate Y. enterocolitica. However, PCR analysis revealed six samples that were positive for Y. enterocolitica (5.9%), confirmed by genetic sequencing. Only the inv gene was detected, which is present in virulent and avirulent Y. enterocolitica strains. There was great difficulty in microbiological isolation due to the difficulty of competitiveness of Y. enterocolitica in a very rich microbiota of raw milk. Although virulence genes known to be present in potentially pathogenic strains of Y. enterocolitica have not been identified, the presence of this pathogen in milk from expansion tanks, identified through PCR and confirmed by genetic sequencing, suggests that Y. enterocolitica may be a risk to public health, especially if milk and its derivatives are consumed without heat treatment.

Prevalence of pathogenic Yersinia enterocolitica in minced meat, pig tongues and hearts at the retail level in the Czech Republic detected by real time PCR

Yersiniosis is the third most frequently reported zoonosis in the European Union and Yersinia enterocolitica is the most common species causing human infections. Pigs are assumed to be the main reservoir of human pathogenic Y. enterocolitica with the presence of bacteria mainly in the tonsils and intestinal content. Undercooked pork and pork products have been suggested as the primary source of human yersiniosis. Nevertheless, data on the prevalence of pathogenic Y. enterocolitica in foodstuffs including pork products are very limited. A molecular based method (real time PCR) targeting the ompF gene (detection of Yersinia genus) and the ail gene (a chromosomally located virulence marker of Y. enterocolitica) was used to determine the prevalence of pathogenic Y. enterocolitica in minced meat and edible pork offal at the retail level in the Czech Republic. A total of 50 pig tongues, 50 pig hearts, and 93 samples of minced meat containing pork were purchased at nine retail outlets in Brno. High detection rates of Yersinia spp. were found in all types of samples (pig tongues, 80.0%; pig hearts, 40.0%; and minced meat, 55.9%). The highest prevalence of pathogenic Y. enterocolitica was found in pig tongues (40.0%), followed by pig hearts (18.0%) and minced meat samples (17.2%). Although from the point of view of food safety the merely molecular detection of DNA of the pathogenic bacteria could represent a false positive result, our results indicate the presence of pathogenic Y. enterocolitica in raw pork products at the retail level in the Czech Republic, which may pose a risk of consumer infection. Sufficient heat treatment and prevention of cross-contamination during preparation of food in the kitchen should be recommended.

Prevalence of Pathogenic Yersinia enterocolitica in Finnish Slaughter Pigs

The prevalence of human pathogenic Yersinia enterocolitica was determined in tonsil and intestinal content samples from 388 healthy fattening pigs at the four biggest Finnish slaughterhouses. These slaughterhouses process 73% of pigs in Finland. Tonsil samples were tested by PCR targeted for yadA, and intestinal samples were cultured. All pathogenic Y. enterocolitica isolates represented bioserotype 4/O:3. The prevalence of Y. enterocolitica in tonsil samples was 60% (95% confidence limit, 55.4 to 65.1%), and its prevalence in intestinal samples was 26% (95% confidence limit, 22.1 to 31.2%). The prevalence of Y. enterocolitica in tonsil and intestinal samples varied between the four slaughterhouses. The tonsil prevalence of Y. enterocolitica was higher in slaughterhouse B, and the prevalence in intestinal content was higher in slaughterhouse C. There were more positive results in both tonsil and intestinal samples in pigs coming from fattening farms than in pigs coming from farrowing-and-fattening farms. A seasonal variation was observed in the prevalence of Y. enterocolitica in intestinal samples, with the highest prevalence during July and August, but no seasonal variation was detected in tonsil samples.

Detection and prevalence of pathogenic Yersinia enterocolitica in refrigerated and frozen dairy products by duplex PCR and dot hybridization targeting the virF and ail genes

Pathogenic Yersinia enterocolitica is involved in yersiniosis through expression of chromosome-borne or plasmid-borne virulence factors. Yersinia enterocolitica is a cold-tolerant pathogen frequently isolated from refrigerated or frozen foods. However, little attention has been focused on the prevalence of pathogenic Y. enterocolitica in refrigerated or frozen dairy samples in China. In this study, we developed a new duplex PCR targeting the plasmid-borne virF gene and chromosome-borne ail gene for detection of pathogenic Y. enterocolitica isolates. We established a detection limit for the duplex PCR of 6.5×102cfu/mL in artificially contaminated dairy samples. In addition, the duplex PCR could detect directly 4.5 to 5.7 cfu of Y. enterocolitica in 5mL of brain heart infusion broth after 6 h of enrichment at 28°C. A newly developed dot hybridization assay further confirmed specificity of the duplex PCR for detection of virulent Y. enterocolitica. Furthermore, 13 Y. enterocolitica and 5 pathogenic strains, from 88 commercial frozen or refrigerated dairy products, were detected successfully by the China National Standard method (GB/T4789.8-2008) and the duplex PCR, respectively. Finally, biotypes and serotypes of pathogenic Y. enterocolitica strains were further characterized. The duplex PCR developed here is reliable for large-scale screening, routine monitoring, and risk assessment of pathogenic Y. enterocolitica in refrigerated or frozen dairy products.

High prevalence of pathogenic Yersinia enterocolitica in pig cheeks

Samples from pork cuts for minced meat and cheeks from processing plants and a slaughterhouse, and modified atmosphere (MA) packaged pork from retail were studied to estimate the prevalence of pathogenic, i.e. virulence plasmid bearing, Yersinia enterocolitica and Yersinia pseudotuberculosis in pork, as well as to quantify pathogenic Y. enterocolitica in pork cuts. Pathogenic (virF-positive) Y. enterocolitica was isolated from 17 pig cheeks (23%) but not from any of the MA-packaged 54 retail pork samples and only from one of the 155 pork cut (0.6%). Most (16/17) of the cheek samples were contaminated with pathogenic Y. enterocolitica 4/O:3 and one with bioserotype 2/O:9. No Y. pseudotuberculosis was isolated. The prevalence of pathogenic Y. enterocolitica was clearly higher (39%) in 155 pork cuts when studied with nested PCR targeting yadA on the virulence plasmid pYV although the contamination level was low varying between 0.1 and 1.6 MPN/g. Raw pork cuts and especially pig cheeks may serve as possible sources for yersiniosis caused by pathogenic Y. enterocolitica.

Prevalence of pathogenic Yersinia enterocolitica in slaughter-aged pigs during a one-year survey, 2010–2011, France

The prevalence of pathogenic Yersinia enterocolitica in French slaughter-aged pigs was estimated by sampling 3120 pigs from 96 batches in 16 slaughterhouses from January 2010 to February 2011. Respectively, 36 batches (20 pigs/batch) and 60 batches (40 pigs/batch) were considered during the cold period and the warm period. Tonsils were swabbed before the chilling step. Pathogenic Y. enterocolitica was detected after enrichment in ITC and streaking on CIN and YeCM media. Typical isolates were confirmed as Y. enterocolitica and biotyped by biochemical tests as described in the ISO 10273:2003 method.Of the tested pigs, 13.7% (CI95% [10.1–17.3]) were found positive for pathogenic Y. enterocolitica and 74.3% (CI95% [64.8–83.8]) of the pig batches contained at least one positive pig. The percentage of positive pigs per batch was generally low; 60.3% of positive batches contained fewer than 5 positive pigs. The prevalence of the pathogen at the batch level remained unchanged throughout this one-year study, but the prevalence in pigs was significantly higher during the warm period than during the cold period. Biotype 4 was the most prevalent biotype among the 827 isolated strains (91.9% of the isolates), followed by biotype 3 (7.25% of the isolates). Six isolates were of biotype 5 and one of biotype 2. Biotype 4 was found in all the 16 participating slaughterhouses, biotype 3 in ten slaughterhouses and biotype 5 in four.This study provides valuable recent figures for the prevalence of pathogenic Y. enterocolitica in French pigs. It also highlights the seasonal aspect of the carriage of this pathogen by pigs, a pattern which differs from those in other countries.

Wide variety of bioserotypes of enteropathogenic Yersinia in tonsils of English pigs at slaughter

The tonsils of 630 pigs from 45 English farms using three different rearing methods (Assured British Pigs, Open Management and Organic) were examined between 2003 and 2005 in order to investigate if the low incidence of human yersiniosis could be attributed to a low prevalence of enteropathogenic Yersinia among English pigs. In addition, different isolation methods were compared, possible differences in prevalence among pigs were studied, as well as the prevalence of different bioserotypes of enteropathogenic Yersinia. A high prevalence and a wide diversity of bioserotypes of enteropathogenic Yersinia compared to other European countries were observed. The prevalence of pathogenic Yersinia enterocolitica was 44% and of Yersinia pseudotuberculosis 18%. Overall, 60% of pigs carried enteropathogenic Yersinia. Y. pseudotuberculosis was detected on 78% of farms and Y. enterocolitica on 69%. The most common bioserotypes of Y. enterocolitica were 2/O:9 (33%) and 2/O:5 (26%), and of Y. pseudotuberculosis 2/O:3 (34%), 1/O:1 (26%) and 1/O:4 (24%). Cold enrichment gave the highest isolation rate for both species. Y. enterocolitica was more prevalent ( P < 0.001) and Y. pseudotuberculosis less prevalent ( P < 0.05) in winter than in summer in Eastern England. Y. enterocolitica was more common in Eastern England and in assured British pigs, whereas Y. pseudotuberculosis was more common in Western England and in organic pigs. Y. pseudotuberculosis 1/O:1 was predominant ( P < 0.05) in Western England. Types 1/O:4 ( P < 0.05) and 2/O:3 ( P < 0.001) predominated in Eastern England. The high prevalence of Y. enterocolitica bioserotypes 2/O:9 and 2/O:5 found in this study suggests that English pigs are an important reservoir of these bioserotypes whereas in other European countries bioserotype 4/O:3 predominates.

Prevalence of pathogenic Yersinia enterocolitica and Yersinia pseudotuberculosis in wild boars in Switzerland

Between October 2007 and March 2008, 153 wild boars shot in the Canton of Geneva in Switzerland were sampled. Fifty-one percent of the animals were males and 49% were females. The age of most (81%) animals varied between 6 months and 2 years. Prevalence of enteropathogenic Yersinia in tonsils and faeces was studied using culture and PCR methods and in tissue fluid of tonsils using an ELISA system. Prevalence of anti- Yersinia antibodies in tissue fluid was 65%. Detection rate of enteropathogenic Yersinia in tonsils of 153 wild boars by real-time PCR was 44%. Ail-positive Y ersinia enterocolitica and inv-positive Y ersinia pseudotuberculosis were detected in 35 and 20% of the animals, respectively. Both species were detected in 10% of the animals. Isolation rate of enteropathogenic Yersinia was low; ail-positive Y. enterocolitica and inv-positive Y. pseudotuberculosis were found in 9 and 3% of the animals, respectively. Prevalence was shown to be significantly higher in tonsils than in faeces. Furthermore, females were more commonly positive than males. This study shows that the prevalence of enteropathogenic Yersinia is high and both enteropathogenic Y. enterocolitica and Y. pseudotuberculosis are common findings in tonsils of wild boars in Switzerland.

Prevalence of pathogenic Yersinia enterocolitica in pigs slaughtered at a Swiss abattoir

Human yersiniosis is the third most common enteric disease after campylobacteriosis and salmonellosis in many European countries. However, epidemiological data on the prevalence of pathogenic Yersinia enterocolitica in animals and humans is insufficient. Pigs are assumed to be the main reservoir of pathogenic Y. enterocolitica because pig is so far the only animal species from which pathogenic strains have frequently been isolated. This work was conducted to study the frequency of ail-positive Y. enterocolitica in pigs slaughtered at a Swiss abattoir. In total, 212 pig tonsils were screened by real-time PCR and culture methods. The prevalence rate of ail-positive Y. enterocolitica in pigs at slaughter was 88% and 34% with PCR and culture methods, respectively. The 148 ail-positive isolates from the 72 culture-positive tonsils were bio-and serotyped. The most common bioserotype was 4/O:3 found in 96% (69/72) of the culture-positive samples. However, pig was also shown to be a reservoir for ail-positive Y. enterocolitica belonging to bioserotypes 2/O:5,27 and 2/O:9, which were detected in 8% (6/72) and 1% (1/72) of the culture-positive samples, respectively. Using PFGE with NotI, only a limited number of different patterns was found. In all, 6 genotypes were obtained when 86 isolates of bioserotype 4/O:3 from 69 samples were characterised and two genotypes (N1 and N4) dominated. The biotype 4 differs clearly from biotype 2 with PFGE. Antimicrobial resistance testing of 77 ail-positive Y. enterocolitica isolates from 72 samples studied with disc-diffusion revealed that all strains were sensitive to cefotaxime, chloramphenicol, ciprofloxacin and tetracycline, which are antimicrobial agents used for treatment of human disease. The isolates of bioserotype 2/O:5,27 differed from the isolates of bioserotypes 2/O:9 and 4/O:3 in resistance to ampicillin and amoxicillin/clavulanic acid.

The prevalence of pathogenic Yersinia enterocolitica among diarrhea patients in Jos, Nigeria

One hundred and fifty (150) stool samples from diarrhoeic children and adults seeking for medical attention (including hospitalized patients) in Vom Christain Hospital (VCH), Mandela Clinic (MC) Vom and Dagott Family Health Clinic (DFHC) Vom were screened for Yersinia enterocolitica infection between August 2005 and August 2006. The isolation methods adopted were direct plating on MacConkey Agar (MCA), Deoxycholate Citrate Agar (DCA) and cold enrichment method using phosphate buffered saline prior to subculture onto selective solid culture media (Cefsulodin Irgasan Novobiocin [CIN] agar). Out of the 150 samples screened, 6 (15%) were positive. The incidence of the infection was highest among those aged 1 - 10 years 3 (7.5%), followed by 21 - 31 years 2 (5%) and 11 - 20 years 1 (2.5%). Serotyped and biotyped, pathogenic Y. enterocolitica (2/O: 9. 4/O: 9) were susceptible to ciprofloxin, floxavid, streptomycin and tetracycline.

The prevalence of pathogenic Yersinia enterocolitica among diarrhea patients in Jos, Nigeria

One hundred and fifty (150) stool samples from diarrhoeic children and adults seeking for medical attention (including hospitalized patients) in Vom Christain Hospital (VCH), Mandela Clinic (MC) Vom and Dagott Family Health Clinic (DFHC) Vom were screened for Yersinia enterocolitica infection between August 2005 and August 2006. The isolation methods adopted were direct plating on MacConkey Agar (MCA), Deoxycholate Citrate Agar (DCA) and cold enrichment method using phosphate buffered saline prior to subculture onto selective solid culture media (Cefsulodin Irgasan Novobiocin [CIN] agar). Out of the 150 samples screened, 6 (15%) were positive. The incidence of the infection was highest among those aged 1 - 10 years 3 (7.5%), followed by 21 - 31 years 2 (5%) and 11 - 20 years 1 (2.5%). Serotyped and biotyped, pathogenic Y. enterocolitica (2/O: 9. 4/O: 9) were susceptible to ciprofloxin, floxavid, streptomycin and tetracycline.

Prevalence of Yersinia enterocolitica in Fattening Pigs

The prevalence of pathogenic Yersinia enterocolitica in pig herds was monitored during six trials (at four different farrowto-finisher farms). Samples were taken throughout the whole rearing period from birth of the piglets to the final fattening stage, and different samples were taken from these pigs during the slaughter process. Environmental samples also were evaluated to identify potential sources of on-farm infection. Y. enterocolitica was isolated using irgasan–ticarcillin–potassium chlorate broth enrichment and cefsulodin-irgasan-novobiocin agar culture. Colonies were identified using bio- and serotyping methods and by PCR assay. Pathogenic Y. enterocolitica were not isolated from fecal samples from piglets and weaners. The only fecal samples positive for Y. enterocolitica were obtained during the fattening stage. The prevalence of Y. enterocolitica in fattening pig herds ranged between 0 and 65.4%. Y. enterocolitica isolates were detected at the abattoir in 38.4% of the tonsils, in 3.8% of the ileocecal lymph nodes, on 0.3% of the carcass surfaces before chilling, and on 0% of the carcass surfaces after chilling. Almost all isolates belonged to bioserotype 4/O:3. Only one strain was identified as O:9. All isolates contained the ail gene. The yopT gene was found in 99.1% of the farm isolates but in only 76.6% of the isolates found at the abattoir from the corresponding carcasses. Although a direct link between porcine isolates and human infection has not been demonstrated, the similarity of the bioserotypes in infected pigs and humans and the presence of virulence factors in porcine isolates should encourage further studies to determine the risk of transmission of Y. enterocolitica to humans from pigs and pork products.

Prevalence of Pathogenic Yersinia enterocolitica in Groups of Swine at Slaughter

In order to estimate the prevalence of swine herds infected with pathogenic Yersinia enterocolitica, 103 lots of market swine were randomly selected at slaughter during six 1-month intervals. Pigs within each lot were sampled by swabbing the oral-pharyngeal surface, poststunning and postexsanguination but prescalding. Ninety-five lots (92.2%) contained at least one pig infected with Y. enterocolitica. Pathogenic strains were defined as those harboring the ail gene which has been identified in Y. enterocolitica that causes human clinical disease. Identification of those strains harboring the ail gene was accomplished using a polymerase chain reaction technique. Twenty-nine lots (28.2%) contained at least one pig from which ail-containing (pathogenic) Y. enterocolitica were isolated. Of the 107 pathogenic Y. enterocolitica isolates identified, 89.7% were serotype O:5 and 3.7% were serotype O:3. The results from this study will aid in the design of future epidemiological investigations concerning on-farm prevalence and associated risk factors for pathogenic Y. enterocolitica. Additionally, the results support the hypothesis that swine are a significant potential reservoir for human infections by Y. enterocolitica.