L-Type Variation and Bacterial Reproduction by Large Bodies as Seen in Electron Micrographic Studies of Bacteroides funduliformis

Chemotherapy of an experimental Fusobacterium (Sphaerophorus) necrophorum infection in mice

An experimental animal model for testing antibiotics in vivo against Fusobacterium (Sphaerophorus) necrophorum has been developed. It incorporates the subcutaneous injection of the bacteria into mice followed by intraperitoneal administration of the antibiotic at 24, 48, 72, and 96 h. Mean effective dose values are based on the number of survivors 21 days after challenge. Tetracycline was the most effective drug tested, with a mean effective dose of 5.0 mg/kg, compared with mean effective dose values of 11.1 for clindamycin, 11.8 for penicillin-G, and 52.9 for lincomycin.

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.

In vivo protection of Fusobacterium necrophorum from penicillin by Bacteroides fragilis

A mixed infection of Bacteroides fragilis and Fusobacterium necrophorum was resistant to treatment with penicillin even though a pure F. necrophorum infection could be successfully treated with penicillin. Since B. fragilis alone did not produce infection, these results indicate that B. fragilis can protect F. necrophorum from penicillin in vivo. The extent of protection afforded by a strain of B. fragilis was related to its level of resistance to penicillin. Only a few cells of B. fragilis were required in the initial bacterial injection. Moreover, protection was demonstrated when B. fragilis cells were injected as late as 24 h after the F. necrophorum cells. Protection of F. necrophorum from penicillin by B. fragilis was also demonstrated in vitro.

Examination of the L forms of group A streptococci for the group-specific polysaccharide and M protein

Two strains of L forms of group A streptococci were examined for group-specific polysaccharide and found to lack this substance. One of these was found to make a substance that had several properties in common with M protein. It is suggested that the absence of the cell wall polysaccharide is responsible for the lack of rigidity of the L form and that the L form of this species closely resembles protoplasts as prepared from other species.

Electron micrographs made from L forms of Proteus and two human strains of pleuropneumonia-like organisms

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Observations upon the cytology and life history of Fusiformis

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