Ribotyping ofFusobacterium necrophorumStrains Isolated from Bovine and Ovine Hepatic Abscesses

A microbiological study was made of 100 strains ofFusobacterium necrophorumisolated from hepatic abscesses in bovine and ovine herds. Differences between the biological activity and ribotypes within the twoF. necrophorumsubspecies were studied. Conventional methods identified 89 isolates asF. necrophorumsubsp.necrophorumand 11 asF. necrophorumsubsp.funduliforme. For ribotyping, 50 strains (35F.n.subsp.necrophorum, 11F.n.subsp.funduliformeand 4 reference strains) were digested with restriction endonucleases (HindIII,EcoRI andBamHI) and examined after hybridization with digoxigenin-labelled cDNA probe transcribed from a 16 and 23S rRNAs fromEscherichia coli. The most discriminating restriction endonuclease enzymes for ribotyping wereEcoRI andBamHI. The presence or absence of two distinct band of 5 kb (EcoRI) and 10.5 kb (BamHI) differentiated the two subspecies. This technique also revealed genetic differences between isolates which could be used in the epidemiological study of clinical processes caused byF. necrophorum.