RIBOTYPING TO COMPARE FUSOBACTERIUM-NECROPHORUM ISOLATES FROM BOVINE LIVER-ABSCESSES, RUMINAL WALLS, AND RUMINAL CONTENTS

Restriction fragment length polymorphism analysis of rRNA genes was em ployed to genetically compare Fusobacterium necrophorum subsp. necroph orum and F. necrophorum subsp. funduliforme isolates from multiple abs cesses of the same liver and isolates from liver abscesses, the rumina l wall, and ruminal contents from the same animal. Four livers with mu ltiple abscesses and samples of ruminal contents, ruminal walls, and l iver abscesses were collected from 11 cattle at slaughter. F. necropho rum was isolated from all liver abscesses, nine ruminal walls, and six ruminal content samples. Chromosomal DNA of the isolates was extracte d and single or double digested with restriction endonucleases (EcoRI, EcoRV, SalL, and HaeIII); then restriction fragments were hybridized with a digoxigenin-labeled cDNA probe transcribed from a mixture of 16 S and 23S rRNAs from Escherichia coli. EcoRI alone or in combination w ith EcoRV yielded the most discriminating ribopatterns for comparison. Within the subspecies multiple isolates from the same liver were indi stinguishable based on the ribopattern obtained with EcoRI. The hybrid ization patterns of liver abscess isolates were concordant with those of the corresponding isolates from ruminal walls in eight of nine sets of samples. None of the six ruminal content isolates matched either t he liver abscess isolates or the ruminal wall isolates. The genetic si milarity between the isolates from liver abscesses, and ruminal walls supports the hypothesis that F. necrophorum isolates of liver abscesse s originate from the rumen.