Phenotypic characteristics and lipopolysaccharides of human and animal isolates of Fusobacterium necrophorum

As part of a collaborative study, six culture collection isolates and 50 coded isolates of Fusobacterium necrophorum were examined for the types of lipopolysaccharides (LPS) they contained, and to see if this related to their reactions in a range of phenotypic tests and their susceptibility to a panel of six antimicrobial compounds, The biotype B type strain, putative biotype B isolates and human isolates were predominantly coccobacillary, had rough type LPS and some of these isolates (8 of 26) required incubation for >2 days to demonstrate lipase activity, The biotype A type strain, putative biotype AB isolates and most putative biotype A isolates (16 of 18) were predominantly rod-shaped, had either smooth LPS or low M-r, rough type LPS and all demonstrated lipase activity within 2 days, The other two putative biotype A isolates were coccobacillary and had rough type LPS, and one of these required incubation for >2 days to demonstrate lipase activity, The results of these latter two isolates more closely resembled biotype B, A few isolates were asaccharolytic, but most fermented one or more of glucose, fructose, maltose and galactose, There was no correlation between fermentation pattern and LPS type, biotype or source of isolate (animal or human) but, with the exception of two abberant isolates, there was good correlation between cellular morphology, type of growth in liquid media and LPS type.