Fusobacterium necrophorum isolated from a hepatic abscess and from mastitic udder secretions in a heifer.

Strains of Fusobacterium necrophorum were isolated from secretions of an udder affected with mastitis (4 strains), an adjacent unaffected udder (3 strains), a superficial inguinal lymph node (2 strains) and a liver abscess (4 strains). These 13 strains were examined bacteriologically together with three known strains: F. necrophorum VPI-2891 and VPI-6161, and Sphaerophorus necrophorus (F. necrophorum) N-167. All strains produced butyric acid from glucose and propionic acid from lactic acid, were positive for the indole reaction, failed to hydrolyse esculin, caused beta-haemolysis and showed sensitivity to penicillin (500 U/ml). They were divided roughly into two groups on the basis of differences in their properties as described below. Six strains belonged to one group and ten strains to the other: the former agglutinated chick red blood cells, formed colonies of type A of Fiévez, were long rods, showed turbid growth in liquid medium and were highly pathogenic for mice; the latter strains, consisting of short bacilli and forming colonies of type B, had no or weak haemagglutinin, showed, in liquid medium, sedimentary growth with a clear supernatant and were not fatal to mice. The 4 strains isolated from the hepatic abscess as well as the F. necrophorum strain VPI-2891 and the Sphaerophorus necrophorus strain N-167 were classified into biovar A. The 9 strains isolated from udder and lymph node, as well as the F. necrophorum strain VPI-6161, were classified into biovar B.