Characterization of the dermal lesions induced by a purified protein from toxigenic Pasteurella multocida

The dermonecrotic effect of purified Pasteurella multocida toxin (PMT) was studied sequentially in guinea pigs and rats. The skin reaction was initially an acute inflammatory reaction, with edema and emigration of neutrophils and a few eosinophils and diapedesis of some erythrocytes. Four hours after intracutaneous injection the vessels were congested and thrombocytes were focally attached to the endothelial wall. Twenty-four h after the injection the inflammatory reaction appeared more severe and venules and arterioles were thrombosed. Necrotic changes were seen in hair follicles and in striated muscle fibers. Crude extracts from P. multocida and Clostridium perfringens injected intracutaneously into guinea pigs induced skin lesions qualitatively similar to the lesions induced by the purified PMT, indicating that dermonecrotic bacterial toxins may share similar biochemical properties.

Production of toxin in strains previously classified as Pasteurella multocida

169 strains of P. multocida ssp. multocida, 24 strains of P. multocida ssp. septica, 22 strains of P. multocida ssp. gallicida, and 8 strains of P. avium and P. canis, respectively, were tested for toxin production in EBL-cell culture assay. Toxin production was only demonstrated in strains belonging to P. multocida ssp. multocida. Toxigenic strains were derived from pigs, calves, cats, dogs, rabbits and turkeys.

The pathogenesis of persistent turbinate atrophy induced by toxigenic Pasteurella multocida in pigs

Six one-week-old piglets were pretreated with a 1% acetic acid solution for two days in one or both nostrils. Three piglets were not treated with acetic acid. Three days after treatment all nine piglets were inoculated in both nostrils with a toxigenic type D strain of Pasteurella multocida. Three piglets were killed seven days after inoculation; one died spontaneously 13 days after inoculation and the remaining pigs were killed at approximately 90 kg body weight, i.e., five to six months of age. All acetic acid-treated animals developed severe atrophy of the turbinates in the treated nostrils. Untreated nostrils were normal. The present results showed that toxigenic P. multocida can induce turbinate atrophy that persisted until 90 kg body weight when the lesions were similar to spontaneous atrophic rhinitis in pigs. The turbinate atrophy was not accompanied by inflammatory reaction, atrophy of other bone structures, or lesions in other organs. The experiment showed furthermore that toxigenic P. multocida may be present in the tonsils of control animals without causing turbinate atrophy. A pathogenesis for atrophic rhinitis in pigs is proposed.

Characterization of Pasteurella species isolated from lungs of calves with pneumonia

During routine bacteriological examination of pneumonic calf lungs it was experienced that many Pasteurella multocida-like isolates had a fermentation pattern different from what is generally accepted for P. multocida sensu stricto. Forty-one out of 50 strains selected for further investigation were phenotypically related and formed a group of indole-, mannitol-and sorbitol-negative P. multocida-like strains, which was tentatively designated taxon 13. Deoxyribonucleic acid/deoxyribonucleic acid hybridizations including both ornithine positive and ornithine negative strains of taxon 13 allowed the classification of the former as P. multocida biovar 6 and the latter as V factor independent strains of Haemophilus avium.

Influence of vaccination of sows with Bordetella-Pasteurella vaccines on the occurrence of atrophic rhinitis among their offspring after experimental infection with Bordetella bronchiseptica and toxigenic Pasteurella multocida

Experimental infections with Bordetella bronchiseptica and a toxigenic strain of Pasteurella multocida were carried out in newborn piglets from 25 sows. Severe progressive atrophic rhinitis corresponding to the natural disease was produced. The effect of vaccination of sows during pregnancy with two vaccines containing antigens from B. bronchiseptica and toxigenic P. multocida on the incidence of nasal lesions in the offspring was studied.

The bacteriology of endocarditis in slaughter pigs

Streptococcus suis was isolated from 11 (10 per cent) out of 107 cases of endocarditis in slaughter pigs from which bacteria of any kind were isolated. Seven of the isolates belonged to the capsular serotypes 1, 2 and 1/2. Four were non-typable owing to lack of capsule. The organism isolated most often was Erysipelothrix rhusiopathiae, which was found in 68 (64 per cent) cases.

The pathogenesis of atrophic rhinitis in pigs induced by toxigenic Pasteurella multocida

The pathogenesis of atrophic rhinitis was studied in an experiment in which piglets were infected with a toxigenic type D Pasteurella multocida strain in the right half of the nasal cavity. Two days before inoculation the nasal mucosa on the right side had been subjected to mild irritation by intranasal instillation of a weak solution of acetic acid. The untreated (left) half of the nasal cavity served as an intrinsic control. Macroscopically, changes in the turbinates were already appreciable at 3 days p.i., and pronounced turbinate atrophy was noted at 7 days p.i. At 14 days p.i. deviation of the snout and almost complete turbinate atrophy was observed. The turbinates in the untreated half of the nasal cavity developed normally. Histologically, the changes were initially characterized by bone resorption mediated by an increased number of osteoclasts. Later osteoclasts were sparse, and there was an apparent disruption of osteoid synthesis. Ultrastructurally, the osteoblasts showed nuclear indentations and dilatation of the endoplasmic reticulum. Since no inflammatory reaction was observed, the hypothesis is advanced that atrophic rhinitis in pigs is caused by a P. multocida-produced factor which will stimulate bone resorption and suppress osteoid synthesis.

Serology of capsulated streptococci pathogenic for pigs: six new serotypes of Streptococcus suis

A total of 138 capsulated strains of streptococci were isolated from pigs with various infections, notably septicemia and bronchopneumonia. Biochemically all strains were similar, and 31 strains were serologically identical to the previously described groups R, S, and RS streptococci, provisionally designated Streptococcus suis types 1, 2, and 1/2 by Elliot. The remaining 107 strains could be divided into six new capsular serotypes of S. suis.

Effect on the incidence of atrophic rhinitis of vaccination of sows with a vaccine containing Pasteurella multocida toxin

Combined experimental infections with Bordetella bronchiseptica and either a toxigenic or a non-toxic strain of P. multocida were carried out in newborn specific pathogen free piglets born to 25 sows. Pigs inoculated with B. bronchiseptica and toxin-producing P. multocida developed severe progressive atrophic rhinitis corresponding to the natural disease. The effect of vaccination of sows with a toxin-containing P. multocida vaccine on the incidence of nasal lesions in the offspring was studied.

The influence of sow colostrum trypsin inhibitor on the immunoglobulin absorption in newborn piglets

The influence of sow colostrum trypsin inhibitor (SCTI) on the immunoglobulin absorption from the gut of 16 newborn colostrum-deprived piglets was investigated in a paired feeding experiment.

Three times at 1 h intervals the piglets were fed an experimental diet consisting of sow milk, purified swine serum immunoglobulins containing agglutinins against Bordetella bronchiseptica, and purified SGTI (diet I) or saline (diet II). The serum concentrations of IgG, IgM, IgA, and antibodies for B. bronchiseptica were measured by single radial immunodiffusion and by a tube agglutination procedure and used to evaluate the immunoglobulin absorption. Four and 6 h after the first experimental meal, blood samples from the piglets given SGTI in their diet had a generally higher level of IgG, IgA and aggutinins against B. bronchiseptica than blood samples from the piglets d no SGTI. No real differences were found in the IgM levels. Although the piglets fed no SGTI all showed a considerable immunoglobulin absorption, the SCTI was found to have a statistically significant positive influence on the IgG and IgA absorption.

The aetiological significance of Bordetella bronchiseptica and Pasteurella multocida in atrophic rhinitis of swine

Experimental infection with either pure culture of Bordetella bronchiseptica or B. bronchiseptica and a toxin-producing strain of Pasteurella multocida was studied in newborn piglets from 26 sows. Pigs inoculated with B. bronchiseptica alone got mild lesions, whereas pigs inoculated with both organisms showed clinical and pathological signs of atrophic rhinitis, corresponding to the progressive natural diseases. The effect of vaccinating sows against B bronchiseptica during pregnancy was studied.

Studies on a haemolytic substance in Yersinia enterocolitica

Yersinia enterocolitica serotype O3 was found to produce a haemolytic substance which could be released from the bacterial cells by sonic disintegration. The substance was non-dialysable, thermolabile, antigenic, and sensitive to trypsin. Chromatographic studies indicated a high molecular weight. Erythrocytes from different mammalian species differed in sensitivity to the haemolytic substance. Y. enterocolitica serotypes O8 and O9 produced no haemolytic substance.

Infection with RS streptococci in pigs

RS streptococci were isolated from pigs that died in an outbreak of septicemia and meningitis in a Danish herd of swine. Most of the affected pigs were 7-9 weeks old. Experimental inoculation of SPF pigs with a culture of the streptococci isolated from the brain of a pig that had died during the outbreak showed that the bacterium was pathogenic for pigs. Out of 35 8-15-week-old pigs inoculated, nine developed arthritis and one died in septicemia. At necropsy, four of the pigs were found to have endocarditis. Blood cultures from pigs with endocarditis were constantly positive throughout the experiment, i.e., until the pigs died 5-7 weeks after inoculation. In vivo loss of capsular antigen was observed. A human strain of R streptococci isolated from a case of septicemia was also shown to be pathogenic for pigs.

Studies on the interaction between different O-serotypes of Yersinia enterocolitica and HeLa cells

Eighty strains of Yersinia enterocolitica were examined for their ability to invade HeLa cells. The following O-serotypes were found to be invasive: 1, 3, 4a, 4c, 5b, 8, 9, 15a, 18, 20, 21 and 22. Biochemically, these types are either indole-, aesculin-, and salicin-negative, or indole-positive but aesculin- and salicin-negative. Other serotypes of Y. enterocolitica did not invade HeLa cells. Biochemically, these non-invasive strains are indole-, aesculin- and salicin-positive. Also the non-sucrose-fermenting strains of O-serotypes 11 and 12 were non-invasive. The interaction with HeLa cells was not restricted to viable bacteria, since also bacterial cells inactivated by formalin or ultraviolet light could gain entrance to the HeLa cells. Heating of the bacteria to 100 degrees C for 30 min. completely inhibited their invasiveness. Monolayer cultures of porcine kidney cells were also invaded by strains which invaded HeLa cells.

Studies on Yersinia enterocolitica isolated from swine and dogs

Yersinia enterocolitica serotype 03 was isolated from the colon contents of 27 (4.5%) of 599 bacon pigs on slaughter. Two (1.7%) out of 115 dogs were positive by culture for this human-athogenic serotype of Y. enterocolitica. A number of other serotypes of Y. enterocolitica were also obtained both from porcine and canine enteric contents (4b, 5a, 6, 7, 11, 12, 15, 17, 19, 26b, and non-typeable strains). All these serotypes are supposedly non-pathogenic for man and may possibly originate from the microflora of the environment. Haemolysis on bovine blood agar was observed for strains belonging to O-serotype 3.

Isolation of Mycoplasma bovoculi from cases of infectious bovine keratoconjunctivitis

Five outbreaks of infectious bovine keratoconjunctivitis were examined for bacteria and mycoplasmas. Mycoplasma bovoculi was demonstrated in four of the five outbreaks. Other mycoplasmatales were represented by Ureaplasma in one sample. Moraxella bovis and Neisseria ovis were found in all the outbreaks, the former being present in the vast majority of the animals. Transmission experiments with Mycoplasma bovoculi and Moraxella bovis in combination were carried out on four young, colostrumdeprived calves. Mycoplasma bovoculi appeared to have an enhancing effect on the pathogenicity of Moraxella bovis.

Studies on immunoglobulins and trypsin inhibitor in colostrum and milk from sows and in serum of their piglets

The concentrations of IgG, IgM, IgA and the specific sow colostrum trypsin inhibitor (SCTI) were measured by radial immunodiffusion in colostrum and milk samples from sows and in serum samples from their offspring during the suckling period. A clear time dependence was found for all the measured variates in both whey and serum. Statistically significant positive correlations were found between, on the one hand, concentrations of IgG and IgA, but not IgM, in sera from 39 suckling piglets 1 and 3 days old, and, on the other hand, concentrations of the same immunoglobulins and of the trypsin inhibitor in maternal colostrum (n = 7). Multiple regression analyses showed that at day 1 and day 3 the levels of both IgG and IgA in serum samples from the suckling piglets were positively influenced by both the SCTI and the IgG or IgA contents in maternal colostrum.

Congenital ataxia and tremor with cerebellar hypoplasia in piglets borne by sows treated with Neguvon vet. (metrifonate, trichlorfon) during pregnancy

In 1976--77 The State Veterinary Serum Laboratory received new-born pigs which had shown nervous disorders immediately after birth. In all the cases the sows had been treated with Nevugon vet. (metrifonate, trichlorfon) during pregnancy. In the majority of the affected litters the morbidity and lethality were 100 per cent. Analysis of the breeding data from some of the herds suggested that the period during which the fetuses are sensitive is rather narrow, i.e., approximately from day 45 to day 63. The disease was reproduced experimentally and it was concluded that oral treatment of pregnant sows with Neguvon vet. about the middle of the gestation period can result in severe nervous disorders in the piglets. Clinically the disease is characterized by ataxia and tremor, and corresponding to that there is a pronounced hypoplasia of the cerebellum and also a reduction in the size of the spinal cord.

Effect of vaccination of sows with Bordetella bronchiseptica on the incidence of atrophic rhinitis in swine

Vaccination of pregnant sows with Bordetella bronchiseptica was performed in an SPF herd with clinical atrophic rhinitis. Agglutinins against the organism were induced in serum and colostrum by the vaccination. The antibody titres were generally higher in colostrum than in corresponding serum samples. The frequency at slaughter of turbinate atrophy (+, ++, +++) was lower among pigs from vaccinated sows (11%) than in pigs borne by unvaccinated sows (20%). In the control group a lower daily weight gain was observed in pigs with turbinate atrophy than in pigs with normal noses. The mean daily weight gain in pigs with turbinate atrophy borne by vaccinated sows was slightly lower than in pigs without atrophy of conchae, but the difference was not significant. A specific immunological prophylaxis might be an alternative to antibacterial treatment in herds where atrophic rhinitis is aetiologically related to B. bronchiseptica infection.

[Feed supplementation with selenium in relation to the vitamin E-selenium deficiency syndrome in pigs (author's transl)]

After the addition of selenium to swine feed (max. 0.1 ppm) was legalized in Denmark in 1975, a marked reduction has occurred in the incidence of hepatosis dietetica (HD) in the material received at the State Veterinary Serum Laboratory for diagnostic examination, while the incidence of mulberry heart disease (MHD) appears to be unchanged (Table I). In a material collected before the addition of selenium to swine feed was permitted, the selenium content in liver and heart was found to be significantly lower in the pigs that had died of MHD than in normal pigs, but higher than in pigs that had died of HD (Table II). These observations tend to support the view that feed supplementation with selenium is more effective to prevent HD than MHD.

[Actinobacillus infections in swine (author's transl)]

Actinobacilli infections in pigs are relatively rare. Most cases were septicaemic in the first week of life. With increasing age manifestations after generalized infections were characteristic, such as arthritis, polyarthritis, endocarditis, nephritis, osteomyelitis and embolic pneumonia. Of 34 porcine strains 33 were identified as A. equuli and only one was identical with A. suis. The justification of retaining this species is discussed.