Identification of Cl. Perfringens was based on atmospheric requirements for growth, colonial morphology, and stormy fermentation in litmus milk. Identification of toxins was based on neutralization tests in guinea pigs and mice.
Cl. Perfringens was isolated from 202 of 399 samples. In 105 additional cultures, colonies characteristic of Cl. Perfringens were present but could not be isolated in pure culture.
Cl. Perfringens type D toxin was identified in only one culture, which was inoculated with ileum contents. Type A toxin was identified in eight of the 24 samples from the one lot of samples in which no type A antitoxin was used. There were no identifications of toxigenic types B, C, or E.
The results indicate that an isolation from necropsy specimens of untyped Cl. Perfringens or type A Cl. Perfringens is in itself of little significance. The infrequency of occurrence of the other toxigenic types in this survey of healthy cattle indicates that recovery of these types from necropsy specimens may be of more significance in determining the cause of death.
相似文献Optimum growth occurred when serum from endotoxin stimulated calves and fetal calf serum were present in a volumetric ratio of 7:3. Inhibition of colony growth occurred when endotoxin-stimulated serum was present at greater than optimum concentration. Normal calf serum, fetal calf serum, mouse L-cell conditioned medium and bovine urine did not stimulate significant colony growth when 8.0 x 104 marrow cells were cultured.
There was a linear relationhip between the number of marrow cells in the cultures and the number of colonies produced. Colony forming efficiency ranged from 13 to 59 colonies per 105 cells plated.
The behaviour of calf colony forming units in suspension culture was similar to that reported for mouse colony forming units.
相似文献Bacterial growth was most common from guttural pouches, wounds and abscesses, and transtracheal washes (TTW), but was less common from uterus, blood, abdominal fluid, and synovial fluids. Streptococcus zooepidemicus was the most common bacterium recovered from guttural pouches, TTW, uterus, and wounds and abscesses. Escherichia coli predominated in abdominal fluids, blood, and synovia. Bacterial sensitivities to common antimicrobials are presented.
相似文献In Ontario, 54% of 156 cows in 15 herds were found to have parasitemia.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pulmonary edema was induced by three different methods: by an aerosol of histamine, by intravenous injection of endotoxin and by intravenous injection of croton oil emulsion. The edema impaired the clearance of P. hemolytica, which was reflected in high numbers of P. hemolytica present in the lungs at four hours after challenge: 260% after histamine, 300% and 400% after endotoxin and 92% after croton oil.
Six days of treatment of four calves with high doses of hydrocortisone acetate produced inconsistent results: two calves treated with a higher daily dose (36 mg/kg) had normal clearance whereas two calves treated with a lower dose had pulmonary edema and displayed lowered clearance with 111% and 31% respectively of P. hemolytica retained in the lungs four hours after challenge.
Immunization of calves by three different methods, a subcutaneously injected bacterin of P. hemolytica (2 calves), single aerosol (2 calves) and four aerosols (4 calves) of live P. hemolytica was reflected in an accelerated pulmonary clearance of P. hemolytica (with a mean of 1.55% of bacteria retained at four hours).
Concurrent infection with parainfluenza-3 virus did not lower the clearance of P. hemolytica in the lungs of 12 calves over 15 days except on the first day following the exposure to parainfluenza-3 virus. These calves had hemagglutinating antibodies against P. hemolytica before exposure.
相似文献The Poly I:C and the swine influenza virus induced production of interferon by PK15 cell cultures, whereas, all three strains of pseudorabies virus at the two concentrations tested failed to induce production of interferon in vitro.
The antiviral substance produced in PK15 cells was identified as an interferon because it was pH stable, non-dialyzable, sensitive to trypsin, non-sedimentable, relatively heat stable, host-species specific and it possessed broad-spectrum antiviral activity. The latter was demonstrated by inhibition of vesicular stomatitis, vaccinia and pseudorabies viruses. Differences in interferon activity against the different viruses were observed.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Diarrhea was observed initially two to four hours after feeding the filtrate prepared from the enteropathogenic E. coli. The duration of diarrhea was five to ten hours. No diarrhea was observed after feeding filtrate prepared from uninoculated medium or cultures of nonenteropathogenic E. coli.
The pH values of the feces increased with the onset of diarrhea and decreased to normal after diarrhea stopped.
No histopathological lesions were found.
相似文献Gross signs common to monocontaminated pigs included distention of the flaccid small and large intestines with fluid contents. Edema was prominent in various tissues of most pigs exposed via the umbilical stump but not in those exposed orally.
Histological lesions were predominantly in the gastrointestinal tract and were variable. At one extreme acute hemorrhagic enteritis was present in two pigs, while at the other extreme in a few pigs it was difficult to distinguish tissues of infected pigs from those of noninfected germfree pigs. Significant histological lesions common to monocontaminates included mild inflammatory reaction, hydropic degeneration of the intestinal epithelium, evidence of interference with normal function of the villus-draining mechanisms, and vascular changes generally indicated by edema.
The findings suggest that interference with normal absorption of nutrients plays at least some role in the pathogenesis of colibacillosis in young gnotobiotic pigs.
相似文献The technique used demonstrated the presence of P. haemolytica in the tracheal air of calves and provides a useful tool for monitoring and determining the phase in the colonization of the respiratory tract in which the majority of the potential pathogen P. haemolytica pass from the nose to the tracheal air and presumably to the lung.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Autolytic change was detected only in the digestive system and the sequence of autolytic events was similar in all groups. The time of onset and rate of progress differed markedly between groups and between segments of the alimentary canal. In the conventional group, autolysis started quickly and progressed rapidly. In the germfree group it was later in onset and slower in progress. The E. coli infected group was intermediate. The initial visible change occurred in the small intestine.
The morphological differences and autolytic changes were described.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Eleven species of clostridia were isolated from a total of 524 products tested. Some products harboured more than one species.
C. sporogenes, one of the most heat resistant organisms, was the most common type isolated.
C. sordellii produced a transient illness in guinea pigs while all other species were innocuous.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
P.haemolytica were isolated from 15 selected major anatomical areas of the nasal cavity in calves with high numbers of P.haemolytica following shipment from Western Canada. When the organisms were present in the nasal cavity of live animals in low numbers, they were isolated from many, but not all, areas. P.haemolytica was isolated post mortem from one or more selected areas of several nasal cavities in spite of negative antemortem cultures.
By the direct fluorescent antibody technique, P.haemolytica was demonstrated at the surface of nasal epithelial cells. Organisms were not seen in or between epithelial cells nor in the ducts nor alveoli of glands. The findings were similar when high and low numbers of P.haemolytica were present in the nasal cavity.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
No sera from 17 deer known to be free of Theileria infection reacted positively to the CF test. Of 35 tests on sera from 12 infected deer having a parasitemia of 2% or less and no accompanying anemia, only 10 (29%) were positive, 2 (6%) were suspicious, and 23 (66%) were negative. Of 65 tests on 8 acutely infected deer, 49 (75%) were positive, 4 (6%) were suspicious and 12 (18%) were negative. Of the 8 deer in which acute theileriasis occurred all reacted to Theileria antigen at one time or another.
A significant correlation was found between CF titers and the degree of parasitemia in acute infections.
Rabbits were hyperimmunized using erythrocytes from either normal or Theileria infected deer. Reciprocal absorption of the hyperimmune sera with Theileria and normal erythrocytic antigens demonstrated the presence of antibodies specific for Theileria.
相似文献In the Calves the compound was very effective (90 to 99%) against adult Haemonchus placei, Ostertagia spp., Trichostrongylus axei and Cooperia oncophora at all levels tested (15, 20, 25, 30, 40 and 60 mg/kg). Against adult Nematodirus spp. dosages of 30, 40 and 60 mg/kg were 81%, 94% and 99% effective respectively
Against arrested Ostertagia spp. larvae, a dosage of 60 mg/kg was 90% effective. Immature stages of Cooperia spp. were susceptible at all levels used but those of Nematodirus spp. required levels of 60 mg/kg for 99% removal.
In the lambs the compound was highly effective against immature and mature nematodes when given orally at all levels tested from 15 mg/kg to 30 mg/kg. Significant reductions (81%) in Moniezia expansa scolices were also observed at dosages from 15 mg/kg to 30 mg/kg.
相似文献It was found that 0.05% or 0.5% formalin added to suspensions of Pseudomonas aeruginosa or ultrasonification of the suspension produced better results than 0.5% phenol, 0.3% alcohol or heat at 100°C for half an hour.
Chinchillas vaccinated with two doses of formolized Pseudomonas aeruginosa bacterins were immune for 36 weeks after the second dose, while all controls died within 48 hours after being challenged.
It was found that the protection afforded by the polyvalent bacterin extended beyond the strains included in the vaccine.
A field survey on 34 ranches which included over 7,700 chinchillas showed very promising and encouraging results.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The labelled endotoxin became associated with neutrophils, monocytes, lymphocytes, platelets and erythrocytes. Association of 3H-endotoxin with formed elements of the blood occurred during the first five minutes of incubation and did not significantly change over the course of a three hour incubation period. Tolerance did not result in increased uptake of 3H-endotoxin by formed elements of the blood. Tolerance of calves to endotoxin is apparently not due to increased uptake of endotoxin by formed elements of the blood.
The Limulus amebocyte lysate assay was unreliable for the detection of endotoxin which was present in calf blood in vitro and requires further modification.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The two hemolysins were neutralized in vitro only by the antitoxin A. Broiler chickens injected I.V. with a Viande-Foie (VF) broth culture of Clostridium perfringens together with the antitoxin A survived, whereas those receiving antitoxin C died. These results seem to indicate that this organism belongs to the type A. This bacillus was sensitive to a great variety of antibiotics, except neomycin.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
No vomitions, symptoms, or lesions of drug toxicity were observed in the medicated dogs.
相似文献![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fluorescence was not seen in known positive preparations stained with non-immune pig globulin conjugates or in preparations from uninoculated cell cultures or pigs, stained with non-immune or immune globulin conjugates.
Mycoplasma hyorhinis was detected by immunofluorescent staining with homologous conjugates, in smears of broth cultures and in tissue sections from pigs with polyserositis.
Immunofluorescent staining was found to be species specific and useful for the early species identification of mycoplasma isolated from pigs.
相似文献