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31.
J L?fstedt J A Roth R F Ross W C Wagner 《American journal of veterinary research》1983,44(7):1224-1228
In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection. 相似文献
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P Sch?ss 《Berliner und Münchener tier?rztliche Wochenschrift》1989,102(11):387-389
Atrophic rhinitis is caused by toxigenic Pasteurella multocida strains. The infection is supported by Bordetella bronchiseptica and other widespread agents and by non-infectious factors damaging the nasal epithelium. The term "infectious multifactorial disease" means in German, that ubiquitous low-virulent agents cause disease when intensified by non-infectious factors. Atrophic rhinitis does not belong to this group but is an infectious disease, caused by a specific agent and influenced by several factors. 相似文献
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M S?rensen 《Nordisk veterinaermedicin》1979,31(1):25-34
A comparative study of investigations from 1970 (before the prohibition against therapeutically used antibiotics as food additives for growth promotion) and from 1978 respectively proves that the prevalence of young pigs and calves with resistant E. coli has increased significantly from 61% to 92% and from 69% to 86% (tables I and II). Figures 1 and 2 show the prevalence of young pigs and calves with antibiotic resistant E. coli with resistance determinants towards sulfonamides, tetracycline, streptomycin, ampicillin, chloramphenicol, neomycin and furazolidone. This shows that the prevalence of young pigs with resistance determinants towards sulfonamides, tetracycline, streptomycin, ampicillin, and chloramphenicol has increased significantly from 1970 to 1978. The same facts apply to the calves. However, the increase in tetracycline resistance is not significant. Neomycin resistant E. coli for both young pigs and calves were only found in 1978. Figure 3 shows the distribution of the number of resistance determinants per young pig and calf with resistant E. coli. The figure shows the significant tendency that the pigs and calves investigated contain resistant E. coli with more resistance determinants in 1978 than in 1970. The distribution of R-factors among resistant E. coli seems to be reduced at first sight but a closer examination establishes that this only goes for R-factor mediated sulfonamide resistance (the experimental conditions may account for this). R-factor mediated streptomycin resistance has increased while R-factor mediated tetracycline resistance was at the same level. On the basis of literature the causes and risks of an increased distribution of antibiotic resistant E. coli are discussed. 相似文献
37.
The prevalence of E. coli, coliforms and Vibrio-like-organisms has been studied at four different sites along the east coast of Zealand. High values were registered in sediment taken from the water-line and at a depth of one meter. Generally there exist significant differences between the bacterial counts of water and sediment, and it is obvious that the greatest concentration is in the waterline sediment. The epidemiological and hygienic consequences of these facts are discussed. 相似文献
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P R?dl 《Folia parasitologica》1979,26(3):265-274
The transfer of fleas Megabothris turbidus, Ctenophthalmus agyrtes, Nosopsyllus fasciatus etc. was investigated by labelling the bank vole (Clethrionomys glareolus Schreb.) with radioactive phosphorus. On the one hand, the process of flea transfer was traced among different individuals of the same host species, and on the other, among different host species (C. glareolus, Apodemus flavicollis Melch.). The investigations revealed that the flea transfer in a rodent nest visited by another host depended partly on the number of fleas present in the nest, partly on the period spent by the new-comer in it. Conversely, the number of fleas transferred in the nest by the newly arrived host depended on the temperature of nest bedding and on the initial nest occupation by other host. 相似文献