Arthritis after experimental infection with Yersinia enterocolitica 0:3 in rabbits

Arthritis in rabbits was caused after experimental oral infection with Yersinia enterocolitica (serotype 0:3, biotype 4, pYV+). Clinical and laboratory signs, bacterial dissemination to the viscera, immune response and morphological findings were studied from day 1 to day 40 post-infection (p.i.). Augmentation of body temperature and erythrocyte sedimentation rate occurred on day 1, and on day 8 p.i. was accompanied by leucopenia. The number of alveolar macrophages was increased up to the 15th day p.i., in contrast to peritoneal macrophage numbers. Extensive bacterial colonization of the internal organs was detected at necropsy until the end of the experiment. Analysis of the cell immune response revealed activation of B cells in peripheral blood, spleen and thymus as well as augmentation of T-cell number in the lymphoid organs examined on days 15, 28 and 40 p.i. Histological changes typical of a generalized infection, such as purulent meningoencephalitis, catarrhal pneumonia and lymphadenitis, were observed. Clinical and morphological manifestations of arthritis were also established. The results obtained show that Y. enterocolitica (serotype 0:3, pYV+) induces a generalized, non-lethal infection in Chinchilla rabbits, complicated by arthritis.     

Reproduction of Brucella titers in swine using experimental infection with Yersinia enterocolitica, serotypes 0:9 and 0:6

Measurable Brucella titres were produced by slow agglutination, slow agglutination at 57 degrees C (heat test), and complement fixation reaction with Brucella antigen in infection experiments with gilts in which Yersinia enterocolitica Serotypes 0:9 and 0:6 were used. Slow agglutination gave brucellosis titres up to 1:1280 and titres against Yersinia enterocolitica, Serotype 0:9, up to 1:20480. The antibody titres stayed persistent throughout the 80 days of the experiment. Yersinia enterocolitica infection was found to be transmissible between the animals. Aspects relating to the development and course of the infection as well as to pathogen detection are discussed.     

A survey for Listeria species, motile aeromonads and Yersinia enterocolitica on bovine and ovine carcasses

One hundred ovine and 100 bovine carcasses in two abattoirs were sampled just after dressing for the presence of Yersinia enterocolitica, Listeria monocytogenes and motile aeromonads. Yersinia enterocolitica was not isolated and only two samples were positive for Listeria spp. In both cases, the Listeria species were not normally pathogenic to man. In contrast, motile aeromonads were isolated from 81% of ovine and 35% of bovine carcasses.     

Studies of the efficacy of Enterocoliticin, a phage-tail like bacteriocin, as antimicrobial agent against Yersinia enterocolitica serotype O3 in a cell culture system and in mice

The efficacy of enterocoliticin, a phage tail-like bacteriocin, as antimicrobial compound against infections with pathogenic Yersinia enterocolitica serotype O3 strains was assessed. In cell cultures, which were infected with the Y. enterocolitica strains 13 169 or 6471/76, bactericidal activity of enterocoliticin was found for bacteria adhering to the surface of eukaryotic cells, whereas bacteria, which had invaded the eukaryotic cells, were not accessible to the bacteriocin. The interaction of enterocoliticin with Y. enterocolitica was further examined in animals. Female BALB/c mice were experimentally infected with the two Y. enterocolitica strains and enterocoliticin was applied as antimicrobial compound by the oral route. Experimental variations concerning the infectious doses of the Y. enterocolitica strains and the time points of application of the bacteriocin were investigated. The increase of the Yersinia CFU titre in animals was retarded at time points shortly after the application of enterocoliticin indicating that the particles were effective on recently introduced Yersinia. The repeated application of enterocoliticin, however, did not prevent the colonization of the gastrointestinal tract by Yersinia.     

Yersinia species infection of lambs and cull cows at an abattoir

The rectal contents of 330 cull cows and 66 lambs were sampled over the 1984-1985 killing season at a New Zealand freezing works for the presence of Yersinia species. Samples from the cows revealed one isolation of Y. pseudotuberculosis and one isolation of Y. intermedia. Samples from the lambs gave thirteen isolates of Y. enterocolitica, three of Y. inter-media, two of Y. pseudotuberculosis and one of Y. frederiksenii. Two of the isolates of Y. enterocolitica were shown to be serotype 0:3. Although no parallel studies were carried out on young cattle or adult sheep, these findings are consistent with the hypothesis that Yersinia infection primarily involves young animals. Thus there exists the potential for transmission of the above species of Yersinia from young animals to man which needs further detailed study.     

Isolation of pathogenic yersiniae from wild animals in Bulgaria

Pathogenic Yersinia strains were isolated between December 1998 and April 1999 from 37 wild animals: rabbit (Lepus europeus), boar (Sus scrofa scrofa), asiatic jackal (Canis aureus), red fox (Vulpes vulpes), mouflon (Ovis musimon), european river otter (Lutra lutra), beech marten (Martes foina), polecat (Musleta putorius) and wild cat (Felis silvestris). It was established that among the wild animals Y. enterocolitica strains of serotype 0:3 predominated, accompanied by Y. pseudotuberculosis strains of serotype 0:3. In one sample from asiatic jackal and one sample from rabbit, Y. enterocolitica serotype 0:8 was isolated. Yersinia enterocolitica and Y. pseudotuberculosis strains were isolated from tonsils and tongues as well as from the viscera--lung, liver, heart, spleen, kidney and lymph nodes, mainly in young animals (1-2 years of age). The results showed that wild animals are a possible natural reservoir for pathogenic Y. enterocolitica and Y. pseudotuberculosis and are included in the epidemiological chain of yersinioses.     

Non-specific seroreactions against Brucella abortus in ruminants in New Zealand and the presence of Yersinia enterocolitica 0:9

The level of non-specific reactions found in the brucellosis serology of ruminants in New Zealand was very low until July 1992. This changed when, in an export consignment of 1071 deer, 35% reacted in the Brucella abortus tube agglutination test with titres varying from 50 to 200 IU. The reactors were also positive in the Rose-Bengal agglutination test and most of them reacted in the complement fixation test with titres varying from 10 to 80 IU. Yersinia enterocolitica 0:9 was later isolated from one deer of this consignment. It was the first isolate of this serotype recovered in New Zealand from an animal. Shortly after, false reactors occurred more frequently than before in sera from Brucella abortus accredited free cattle herds. As the involvement of Yersinia enterocolitica 0:9 was suspected in these cases, faecal samples from reactors and in-contact animals were cultured for this organism. Yersinia enterocolitica 0:9 was isolated from nine of 19 herds showing one or more false Brucella abortus seroreactions. Prior to 1990, Yersinia enterocolitica serotype 0:9 had not been isolated in New Zealand, despite the recovery of a number of other bio- or serotypes of the organism from humans and animals. From 1990 onward, serotype 0:9 began to be isolated from human faecal samples with increasing frequency. Since the first isolations from deer and cattle in 1992, it has now also been recovered from a cat and an alpaca and from cattle without any association with false positive Brucella abortus reactions. All serotype 0:9 isolates were of biotype 2.     

Development of an ELISA procedure to detect swine carriers of pathogenic Yersinia enterocolitica

An enzyme immunoassay (ELISA) was developed to detect antibodies in pigs against the lipopolysaccharidic antigen of the three serotypes of Yersinia enterocolitica mostly associated with human infections. Recent epidemiological evidence has demonstrated that pigs and pork are important sources of yersiniosis in humans. The purpose of this study was to clarify the use of an ELISA to detect swine carriers of this enteroinvasive bacteria by examining seroconversion and tissue distribution of Y. enterocolitica following experimental infection and then screening pigs at a slaughterhouse by bacterial culture and ELISA. It was observed that seroconversion occurred in animals experimentally inoculated with Y. enterocolitica but not with other enterobacteria. It was also found that 27% of swine at a slaughterhouse carried the bacterium in their tonsils and/or intestinal tract, whereas 66% showed serological evidence of previous infection. About 6% of swine at slaughter were culture-positive, but seronegative. Although, similar numbers of swine showed serological evidence of previous infection by each of the three Y. enterocolitica serotypes tested, virtually all culture isolates belonged to serotype O:3. This ELISA appears as a valuable control tool that can be used, in conjunction with culture, to identify pigs or herds infected by strains of Y. enterocolitica associated with human infections.     

Presence of Yersinia enterocolitica in tissues of orally-inoculated pigs and the tonsils and feces of pigs at slaughter.

In order to study the early events associated with infection of swine by Yersinia enterocolitica, 42 five-week-old crossbred piglets were inoculated per os with approximately 10(8) Y. enterocolitica O:3. Groups of 5 animals (and one negative control) were euthanized 30 min, 3, 6, 12, 24, 48 and 72 h following the infection. Palatine tonsils, retropharyngeal and mesenteric lymph nodes, esophagus, duodenum, jejunum, ileum (and Peyer's patches), stomach, liver, spleen and feces (from colon) were collected and analyzed for the presence of Y. enterocolitica by standard bacteriological procedures. Natural infections were also analyzed, as a complementary study, by taking one-gram samples of fecal material and tonsils from 291 pig carcasses less than 3 h after slaughter and culturing them for Y. enterocolitica using a cold enrichment technique. Within 30 min, Yersinia enterocolitica O:3 was already present at most sites. The presence of Y. enterocolitica in the liver of 3 out of 10 animals and also in the spleen of 3 out of 10 piglets, within the first 3 h postinfection, but not at later times (with one exception), probably indicated a transient bacteremia accompanying the initial stages of infection. The tonsils were colonized in most animals (13/20) as the bacteria remained present from 12 to 72 h postinfection, while only 4 out of 20 fecal samples were found to be positive over the same period. Up to 10(4) colony-forming units of Y. enterocolitica per gram of tonsil and fecal material were recovered. Finally, among the 291 animals sampled at the abattoir, a total of 79 were found positive, 70 of the tonsils sampled were positive, and bacteria were recovered in 17 fecal samples. It is therefore suggested that palatine tonsils are the most reliable tissue for the indication of an infection/colonization by Y. enterocolitica O:3 in swine and that the removal of this tissue during the slaughter process should be considered in order to minimize the possibility of contamination of meat products.     

Presence and coincidence of Listeria spp., motile aeromonads and Yersinia enterocolitica in a cold-smoked salmon processing and packing plant

Environmental samples and samples of partially processed fish from a cold-smoked salmon processing and packing plant, and product samples purchased from retail outlets, were examined for the presence of Listeria monocytogenes and other Listeria spp., motile aeromonads and Yersinia enterocolitica. Listeria spp. were not isolated from raw fish but were a contaminant of processed and partially processed fish. Listeria spp. were also detected in 18.8% of surfaces in contact with fish. Unlike Listeria spp., motile aeromonads were isolated from the raw fish but not from the finished product. They were more frequently isolated from environmental sources than Listeria spp. Yersinia enterocolitica was not isolated from any of the samples tested. Little evidence was found to show a coincidence of motile aeromonads and Listeria spp., since only one subset of samples showed such a link. It is concluded that contamination by Listeria spp. was from environmental sources at the processing plant at, or beyond, the slicing stage. Reducing the number of wet areas and special cleaning and sanitation considerations for a contaminated site (the freezer seal) are suggested as ways of reducing contamination of the product.     

Differentiation of Brucella abortus and Yersinia enterocolitica serotype 09 infections in cattle: the use of specific lymphocyte transformation and brucellin skin tests

The lymphocyte transformation test (using an in vitro whole-blood lymphocyte stimulation procedure) and the Brucellin skin test were applied to five heifers infected with virulent Brucella abortus strain 544, five cows inoculated with Yersinia enterocolitica serotype 09, and four non-exposed cows. Lymphocytes from Brucella-inoculated animals persistently gave very high blastogenic reactions indicative of active Brucella infection. The test was persistently negative in Yersinia-infected and non-exposed cattle. Four of the five cows infected with Yersinia enterocolitica type 09 and all four control cattle were persistently negative to the delayed hypersensitivity skin reaction with brucellin. All cattle infected with Yersinia enterocolitica type 09 were strongly positive to the Rose Bengal, Serum agglutination, Complement fixation and Antibovine globulin tests using Brucella abortus antigens. One lactating cow infected with Yersinia enterocolitica type 09 was positive to Brucella milk ring test. These results indicate that standard Brucella serological tests are unreliable in differentiating the two infections in cattle and that both the Lymphocyte transformation and brucellin skin tests could be used to differentiate bovine brucellosis from yersiniosis.     

Immunotoxic effects of T-2 mycotoxin on cell-mediated resistance to Listeria monocytogenes infection

The effect of T-2 toxin on cell-mediated resistance to bacterial infection was evaluated in mice exposed to Listeria monocytogenes. Mice were inoculated with 4.0 X 10(5) (LD50) or 4.0 X 10(4) (nonlethal) L. monocytogenes on day 0 and treated orally on days 0, 1, 2, and 3 with 2.0, 1.0, or 0 mg/kg T-2 toxin. Toxin induced suppression of resistance was indicated by the rapid growth of Listeria in the spleen and by significant (P less than 0.005) increases in mortality due to listeriosis. Necrosis and depletion of lymphoid tissue, lymphopenia, and a marked decrease in the influx of lymphocytes and macrophages into Listeria elicited peritoneal exudates and at sites of infection in the liver and spleen occurred in the toxin treated mice. The immunotoxic effect of T-2 toxin on cell-mediated resistance to listeriosis was dosage dependent and attributed to toxin induced lymphoid depletion and the failure of surviving lymphocytes and mononuclear cells to clear the host of infection.     

Enteritis in sheep and goats due to Yersinia enterocolitica infection

Yersinia enterocolitica biotype 5, serotype 02,3 was isolated from the intestine of 38 sheep and 8 goats submitted to the laboratory for disease diagnosis. Infected animals were usually young, had diarrhoea and were in poor condition or emaciated. A number were moribund or dead when submitted. Characteristic microabscesses were demonstrated in the intestine of 5 of 38 sheep and 3 of 8 goats and no alternative cause of morbidity or mortality was established in these animals. Of the 33 sheep and 5 goats infected with Y. enterocolitica in which microabscesses were not demonstrated, a number of other diagnoses were made, including internal parasitism (18), selenium deficiency or white muscle disease (6) and cobalt deficiency (2), so that morbidity and mortality were possibly unrelated to Y. enterocolitica infection. Five of 6 sheep exposed experimentally by mouth to Y. enterocolitica biotype 5, serotype 02,3 developed an intestinal infection. Although infected sheep showed no clinical evidence of disease and haematological and biochemical indices remained normal, multiple intestinal microabscesses typical of yersiniosis were demonstrated in 3 of 5 infected sheep. It is concluded that Y. enterocolitica biotype 5, serotype 02,3 is an enteropathogen of sheep and goats. Since sheep and goats may be the specific hosts of this bacterium, its virulence for these species is apparently low. Morbidity and mortality may, therefore, be unusual manifestations of infection.     

Humoral and Delayed-type Hypersensitive Responses againstListeria monocytogenes Phosphatidylinositol-specific Phospholipase C in Experimentally Infected Buffaloes

The kinetics of antibody production against phosphatidylinositol-specific phospholipase C (PI-PLC) and the isolation pattern of Listeria monocytogenes from bacteriological samples were studied following oral infection of buffalo calves with 3 x 10(9) cells each of pathogenic L. monocytogenes. Antibodies to PI-PLC appeared by 4-8 days post infection (PI), with a peak between days 7 and 16 PI, when tested by indirect plate-ELISA. Subsequently, antibody titres in all the animals declined and became undetectable on days 26-35 PI onwards until the study concluded on day 211 PI. Dot-ELISA could detect the antibodies to PI-PLC 1-2 days earlier and at higher titres as compared to plate-ELISA. L. monocytogenes could be recovered from faeces, nasal swabs and haemocultures from days 2 to 33, days 2 to 21 and days 11 to 17 PI, respectively. Antibodies to PI-PLC were detected during the course of active infection but their titres declined sharply once animals became culturally negative. Sonicated antigen elicited the highest delayed-type hypersensitivity response, followed by PI-PLC and listeriolysin O.     

Enterotoxin production at 4, 22, and 37 degrees C by Yersinia enterocolitica and Yersinia enterocolitica-like bacteria isolated from porcine tonsils and pork products

Altogether, 71 strains of Yersinia enterocolitica and Yersinia enterocolitica-like bacteria from porcine tonsils and pork products were examined for their ability to produce enterotoxin using the infant mouse assay. Of these, 37 strains (52.1 %) produced enterotoxin at 22 °C, 3 were positive at 4 and 22 °C, and 1 was enterotoxigenic at 22 and 37°C. No strain was positive at all 3 temperatures. The highest prevalence of enterotoxin production at 22°C was detected in serotype 0:11 (80.0%), followed by 0:3/ biotype 4 (74.2 %), and 0:12 (66.7 %). Enterotoxin production at 4°C was recorded in 2 (15.4 %) of the Yersinia kristensenii strains (0:11, 0:12) and 1 of the Yersinia enterocolitica strains, (0:3) examined. One Yersinia kristensenii strain (0:11) was enterotoxigenic at 37 °C. The results indicate that enterotoxin production is a common feature of yersiniae isolated from porcine tonsils and pork products in Norway and may represent a possible source of food borne intoxication.     

Experimental infection of newborn piglets with Yersinia enterocolitica: an animal model of enteritis

Newborn, colostrum-deprived Large White piglets infected with a human isolate of Yersinia enterocolitica biotype 4 serotype 0:3 were used as an animal model of yersiniosis. Within 3 hours of birth and before being fed, 14 piglets were inoculated orogastrically with 10 ml of bacterial suspension containing about 3 x 10(10) colony forming units of Y. enterocolitica, followed by 10 ml of 10% NaHCO3 solution. A further 14 litter mates acted as controls. The animals were reared on an artificial milk formula and humanely killed at 3 or 5 days after infection. Of the 14 infected piglets, 11 became anorexic, five vomited and 13 developed diarrhoea. Yersinia enterocolitica was isolated from their faeces and small intestinal contents. Body weight gains and the plasma glucose concentrations were significantly lower in the infected piglets than in the controls. Damage to the mucosa was observed in the whole gastro-intestinal tract, but was more severe in the small intestine and caecum. Micro-abscesses surrounding bacteria were present at the base of the villi in all parts of the small intestine, particularly in the distal ileum. Lesions were present in the small intestine in all infected piglets by day 3 and were more extensive by day 5. The liver was damaged by day 5, but not day 3. Similar lesions were seen in the mucosa of the stomach in one of six piglets at 3 days and in two of eight piglets at 5 days. It is hypothesised that the hypoacidity in the newborn stomach, as well as the administration of the NaHCO3 solution, may have produced favourable conditions for bacterial invasion.     

Yersinia enterocolitica infection in breeding colonies of ruffed lemurs

Two outbreaks of yersiniosis caused by Yersinia enterocolitica occurred in breeding colonies of red ruffed lemurs (Varecia variegata rubra) and black and white ruffed lemurs (Varecia variegata variegata) housed in outdoor enclosures during the winter breeding season and spring birth season, respectively. Seven of 11 animals at risk in the combined outbreaks became ill, and 3 died of acute to chronic infection. Clinical signs included anorexia, lethargy, diarrhea, abdominal pain, and hyperpyrexia. Necropsy findings included ulcerative enterocolitis and multifocal necrosis and abscess formation in mesenteric lymph nodes, liver, spleen, kidneys, and lungs. Histologically, lesions were characterized by necrotizing inflammation containing masses of basophilic bacteria. Yersinia enterocolitica serotype 0:2 was isolated from lesions. Neomycin sulfate given orally and chloramphenicol given intramuscularly were effective in treatment early in the course of the disease or in mild cases. In severe cases, lemurs did not respond to antibiotic and fluid therapy. Exposure to soil contaminated with infected rodent feces, stress, and behavioral factors in the ruffed lemur species are believed to have precipitated the infection.     

Influence of the route of administration on efficacy and tissue distribution of ivermectin in goat

The tissue concentration and efficacy of ivermectin after per os and subcutaneous administration were compared in goats experimentally infected with Trichostrongylus colubriformis (ivermectin-susceptible strain, INRA). Infected goats (n = 24) were treated per os (n = 9) or subcutaneously (n = 9) with ivermectin, 0.2 mg/kg, or kept as not treated controls. The faecal egg counts and small intestine worm counts were determined. Ivermectin concentration was measured in the plasma, gastrointestinal tract, lung, skin or hair, liver and adipose tissues at 0, 2, 7 and 17 days post-treatment. The efficacy of ivermectin against T. colubriformis infection in goat was 98.7 and 99.9% for subcutaneous and oral administration, respectively. Ivermectin concentration declined with time and only residual concentration was measured at 17 days post-treatment in plasma and gastrointestinal tract. Ivermectin concentration was higher after subcutaneous compared to per os injection in most of the tissue examined. In skin, hair and subcutaneous adipose tissue ivermectin persisted at significant concentrations 17 days post-treatment for both routes of administration. In our experimental conditions, ivermectin provides similar efficacy against T. colubriformis after subcutaneous or per os administration in goat. However, the lower ivermectin levels in tissues after per os administration suggest that the lasting of efficacy may be shortened after per os compared to subcutaneous administration especially in animals with poor body condition in pasture where re-infection occurs quickly after anthelmintic treatment.     

Experimental studies on Yersinia enterocolitica infection in chickens exposed at 1-day old

1. Seventy 1-d-old broiler chicks were experimentally inoculated orally with Yersinia enterocolitica serotype 0:3 (1.4 x 10(11) cells/chick), 0:8 (1.6 x 10(11) cells) and 0:9 (8.0 x 10(10) cells) with or without sodium bicarbonate solution (10 g/l). 2. None of the chicks showed any overt clinical signs or pathological lesions although the organism was demonstrated in the ileum and shedding was observed up to 13 d after exposure. 3. The serotype, dose of Y. enterocolitica and administration of NaHCO3 solution had no significant effect on the weight gain of exposed broiler chicks. 4. Y. enterocolitica was isolated from the liver, spleen, heart and gall bladder of infected chicks 70 d after exposure. 5. Although broiler chicks appear resistant to high doses of Y. enterocolitica by the oral route, detection of the organism in the organs of infected chickens is of public health significance.     

Competitive exclusion of Yersinia enterocolitica biotype 4, serotype O:3 by Yersinia enterocolitica biotype 1A, serotype O:6,30 in tissue culture and in pigs

AIMS: To study the adhesion properties of a biotype 4, serotype O:3 (human pathogenic) strain of Yersinia enterocolitica and to determine if adhesion in vitro and colonisation in vivo can be prevented by competition with a biotype 1A, serotype O:6,30 (non-pathogenic) strain. To study interaction between Y. enterocolitica biotype 4, serotype O:3 and cultured epithelial cells using the synthetic tripeptide arginine-glycine-aspartic acid (RGD). METHODS: The human intestinal epithelial (HEp-2) cell line was used for in vitro studies. Inocula of Y. enterocolitica biotype 4, serotype O:3 radiolabelled using tritium were incubated with HEp-2 cells and RGD tripeptide, or with Y. enterocolitica biotype 1A, serotype O:6,30 sequentially or concurrently, then washed and lysed, and radioactivity measured to determine the effect of RGD on adhesion, and competitive exclusion of pathogenic by non-pathogenic bacteria. For in vivo studies, two groups of 5-week-old piglets (n=5/group) were sequentially inoculated orally with 5 x 10(9) colony forming units (cfu) of either a non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica followed by a pathogenic biotype 4, serotype O:3 strain, or vice versa. Pigs were monitored for carriage of strains using bacterial culture and a multiplex polymerase chain reaction (PCR). RESULTS: The RGD tripeptide significantly inhibited adherence of the pathogenic Y. enterocolitica strain to cultured epithelial cells, suggesting that adhesion involved the RGD tripeptide sequence. The non-pathogenic biotype 1A, serotype O:6,30 strain of Y. enterocolitica prevented adhesion of the pathogenic strain to cells in vitro when allowed to adhere first. Pathogenic Y. enterocolitica was consistently isolated from rectal swabs from 80-100% of pigs on all sampling occasions but not from oral swabs after 14 days in pigs first inoculated with the non-pathogenic strain or at 26 days in pigs first inoculated with the pathogenic strain. CONCLUSIONS: A non-pathogenic strain of Y. enterocolitica reduced adhesion of a human pathogenic strain in vitro but not in vivo.