Experimental Yersinia enterocolitica placentitis in sheep.

A strain of Yersinia enterocolitica of O serogroup 6,30 isolated from the liver of an aborted ovine fetus was inoculated intravenously into a group of pregnant ewes at about 90 days gestation and produced placentitis with abortion or delivery of infected lambs about 50 days later. Y. enterocolitica of the same serogroup was recovered from the necrotic placental cotyledons and most other fetal tissues and could be isolated from vaginal discharges of the ewes for a least 2 weeks after abortion. Histological changes were consistent with an acute bacterial necrotizing placentitis and systemic infection of the fetus. Subsequent pregnancies in the ewes proceeded to term without evidence of infection.     

Yersinia enterocolitica. Experimental pathogenicity for chinchilla.

An intragastric inoculation of approx. 2 × 10¹⁰ Yersinia enterocolitica cells killed chinchillas in three days in the case of four strains out of six tested. Because of the sensitivity of chinchillas to this bacterium, the test is useful for the evaluation of the virulence and invasiveness of Y. enterocolitica isolates. This animal model could also be used for studies on the mechanism of the infection.     

The pathogenicity of Yersinia enterocolitica for piglets.

The pathogenicity of Yersinia enterocolitica, a bacterium that has been isolated frequently from healthy swine, was studied in piglets by oral challenge of two litters, one derived by cesarean section and deprived of colostrum, and the other delivered at full-term. Eight cesarean-derived piglets were divided into groups of two and challenged with four serotypes of Y. enterocolitica (O:8, O:21, O:3, O:13). Two deaths occurred and two piglets were killed because of severe illness before termination of the experiment eight days after challenge. Surviving piglets showed no clinical signs of illness. Rectal cultures were consistently positive and all cesarean-derived piglets were colonized in the small intestine and throat at necropsy. Full-term piglets were allowed access for 36 hours to sow colostrum containing low levels of antibody against the challenge strains. Six full-term piglets challenged with three serotypes of Y. enterocolitica (O:8, O:21, O:13) survived for 15 days without any signs of illness. These piglets had fewer positive rectal cultures and showed less extensive colonization of internal organs at necropsy than did cesarean-derived piglets. It is uncertain whether this increased resistance to infection with Y. enterocolitica resulted from colostrum-derived antibody, intestinal colonization with other bacteria, or an improved physical condition which accompanied full-term development. Nevertheless, the results of this challenge experiment suggest that piglets are capable of restricting colonization by Y. enterocolitica to the throat and intestinal tract without development of serious illness.     

仔猪粪便中小肠结肠炎耶尔森菌的检测

应用常规细菌分离培养鉴定技术对西宁市某猪场断奶仔猪粪便中小肠结肠炎耶尔森菌带菌率进行了调查。结果显示,在60头断奶仔猪粪便中共检出7株小肠结肠炎耶尔森菌,阳性率为11.7%(7/60)。致病性试验表明有3株分离菌对小鼠具有致死效应。     

Yersinia enterocolitica infection in goat. A serological and bacteriological investigation

The distribution of agglutinating antibodies to Yersinia enterocolitica type 2 in sera from goats in an infected herd, and in 190 other animals from different parts of the country was studied. The faecal excretion of Yersinia enterocolitica from the same animals was also examined. Experimental inoculations of two goats were carried out. The serological results indicate that subclinical cases had occurred in the infected herd during the enzooty and during the following months. Faecal excretion of the organism was observed during the first month after the acute phase of the disease. It was found to be difficult to induce the disease experimentally, but clinical signs were observed in 1 goat after injection of live Yersinia enterocolitica intraperitoneally. The Widal-titre rose to 1/1250 during the first 2 weeks after the inoculation and then fell to 1/80 during the next 2 months. The serological results indicate infections with Yersinia enterocolitica, if a Widal-titre of at least 1/80–1/160 in the first month after the acute phase of a disease and a fall to a low level during the following months are found. Among animals from different partst of the country 16.3 % had a Widal-titre which indicated infection with Yersinia enterocolitica during the previous 3–6 months.     

Yersinia enterocolitica infections: 1. Impact on animal health

In Europe, yersiniosis is mainly caused by the bacterial species Yersinia enterocolitica. The clinical picture of yersiniosis in farm animals including pig, chinchilla, cattle, small ruminants and the pet animals dog and cat is described in detail. However, data on seroprevalence and prevalence in these animals are not available. Therefore, further research is needed in the fields of epidemiology and epizootiology.     

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.     

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.     

Immunostimulating effect of culture filtrates of Yersinia enterocolitica

Application of sterile culturing supernatant of Yersinia (Y.) enterocolitica (tested serovars were 03 and 08) caused significantly accelerated transplant rejection in mice of various inbreeding strains. Action correlated with dosage (r = -0.92). C57B16 mice were tested for their pregnancy rates in response to the same filtrate (serovar 03), with 5.5 live births per mating being recorded from 47 control matings but only 4.4 from 45 experimental matings (alpha less than 0.0025). The mean gestation period of experimental animals was extended by five percent over that of simultaneous controls (alpha = 0.25). Particular reference is made in this paper to Vesikari et al. (1987) who found Y. enterocolitica to function as interleukin-1 inductor via lipopolysaccharide. The active substance tested in this context, however, proved to be thermolabile, with 30 minutes of heating to 56 degrees C eliminating the action tested before. Y. enterocolitica infections were frequently found to coincide with rheumatoid arthritis, and evidence has been produced to the unspecific stimulating effect of Y. enterocolitica culture filtrates (testing being applied to serovar 03, biovar 4 and serovar 08, biovar 2). It is against the background of these aspects that chronic and other infections by Y. enterocolitica are considered to be of substantive relevance to the etiopathogenesis of autoimmune diseases, above all rheumatoid arthritis.