Human necrobacillosis, with emphasis on Lemierre's syndrome.

Lemierre's syndrome is the classical presentation of human necrobacillosis. It is characterized by a primary infection in the head in a young, previously healthy person who subsequently develops persistent high fever and disseminated metastatic abscesses, frequently including a septic thrombophlebitis of the internal jugular vein. The main pathogen is Fusobacterium necrophorum, an obligate anaerobic, pleomorphic, gram-negative rod. Clinical microbiologists have a key role in alerting clinicians and advising proper antibiotic treatment when the characteristic microscopic morphology of the pleomorphic F. necrophorum is seen in Gram stains from positive anaerobic cultures of blood and pus. Early diagnosis and prolonged appropriate antibiotic treatment with good anaerobic coverage are crucial to reduce morbidity and mortality. F. necrophorum also causes human necrobacillosis with foci caudal to the head, mainly in elderly patients with high mortality related to age and predisposing diseases, such as cancers of the primary focus.

Actin degradation concomitant with Fusobacterium necrophorum subsp. necrophorum adhesion to bovine portal cells.

The effects of Fusobacterium necrophorum subsp. necrophorum on cellular actin were investigated using tissue-cultured bovine portal cells. Fluorescence studies revealed the appearance of intense fluorescent spots on the cellular actin and the spots increased in a time dependent manner. Sodium dodecyl sulphate polyacrylamide gel electrophoresis profiles manifested partial or complete degradation of actin preparation after treatment with the bacterial cells. These findings suggest that the bacterial cell wall may contribute to the degradation of the cellular actin during the initial stage of the infection caused by F. necrophorum subsp. necrophorum.

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.

Pleomorphism of fusobacteria isolated from the cockroach hindgut.

Fusobacteria are commonly isolated from the hindgut of the cockroach Eublaberus posticus . Eleven strains isolated from E. posticus by us were keyed to four species, Fusobacterium necrophorum, F. varium , F. gonidiaformans , and F. prausnitzii , using current taxonomic criteria. With the exception of F. gonidiaformis , all species showed rods with swollen centers and large bodies. The pleomorphism of F. varium was examined by phase microscopy and scanning and transmission electron microscopy. The pleomorphic process begins with a gradual swelling at the center of the rod until a large round body is formed. Some of these round bodies then fragment, giving rise to rod-shaped cells. When 10% yeast extract was added to growth media, pleomorphism was not induced. A dialyzable factor was found to account for this observation. Fermentation of [1-14C]glutamic acid gives rise to butyrate labeled in the carboxyl carbon, indicating that butyrate is formed by the hydroxyglutarate pathway which may be characteristic for the genus Fusobacterium.