Effects of minocycline and other antibiotics on Fusobacterium necrophorum infections in mice.

Several antibiotics were evaluated in model infections produced in mice with each of two strains of Fusobacterium necrophorum. In one model, local abscesses occurred at the site of subcutaneous injection; in another intra-abdominal abscesses were produced when the organisms were injected into the peritoneal cavity. Treatment with effective antibiotics prevented the formation of abscesses or minimized the size of the lesions. Several treatment schedules were used. Minocycline was the most active antibiotic of the seven agents tested against both strains and in both models. Clindamycin was equal to minocycline against one strain with certain multiple dose treatment schedules and less active with others. Protective effects in mice were achieved with serum levels of minocycline and clindamycin that appear to be clinically achievable. Doxycycline was less active than minocycline, and tetracycline was relatively ineffective, as were cephalexin, ampicillin and penicillin G.