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Experimental observations on the pathogenesis of necrobacillosis

  • G. R. Smith (a1), L. M. Wallace (a1) and D. E. Noakes (a2)

Earlier studies showed that the minimum infective dose (>106 organisms) of a virulent strain of Fusobacterium necrophorum could be greatly reduced by suspending the fusobacteria in sub-lethal doses of cultures of other bacteria such as Escherichia coli before inoculating mice subcutaneously.

In the present study the infective dose of the same strain of F. necrophorum was reduced by a factor of >103 by suspending the fusobacteria in sub-lethal doses of 5% homogenate of gaur or wallaby faeces. Sterile faecal filtrate had no such effect. The sites of low grade infection produced by the prior subcutaneous injection of E. coli culture or gaur faecal suspension were susceptible to superinfection by doses of F. necrophorum far below those required to infect normal tissue.

This work helps to explain the production of necrobacillosis by the faecal contamination of small wounds. It proved impossible, however, to produce necrobacillosis in mice by the subcutaneous injection of faecal suspensions from 33 farm cattle. This suggests that the proportion of cattle with virulent F. necrophorum in their faeces is low.

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2.Beerens, H, Fievez, L, Wattre, P.Observations concernant 7 souches appartenant aux espèces Sphaerophorus necrophorus Sphaerophorus fundutiformis, Sphaerophorus pseudonecrophorus. Annls Inst Pasteur Lille 1971; 121; 3741.
3.Hofstad, T.Fusobacterium necrophorum-pathogenic organism? J Med Microbiol 1985; 20: vii.
4.Shinjo, T, Miyazato, S, Kaneuchi, C, Mitsuoka, T.Physiological and biochemical characteristics of Fusobacterium necrophorum biovar A and biovar B strains and their deoxyribonucleic acid homology. Jap J Vet Sci 1981; 43: 233–41.
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7.Smith, GR, Oliphant, JC, Parsons, R.The pathogenic properties of Fusobacterium and Bacteroides species from wallabies and other sources. J Hyg 1984; 92: 165–75.
8.Deacon, AG, Duerden, BI, Holbrook, WP.Gas-liquid chromatographic analysis of metabolic products in the identification of Bacteroidaceae of clinical interest. J Med Microbiol 1978; 11: 8199.
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
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