Effect of chemotherapeutic agents on Pasteurella anatipestifer infection in White Pekin ducklings.

In a series of experiments, various chemotherapeutic agents administered in feed were evaluated for their efficacy against experimental Pasteurella anatipestifer (PA) infection in White Pekin ducklings. The feeding of medicated diets was started 3 days prior to challenge and continued throughout each experiment. Novobiocin and lincomycin, when fed at adequate concentrations, were the most effective medicaments tested. Mortality in treated groups was 0-18% compared with 45-92% mortality in controls. Sulfadimethoxine-ormetoprim, sulfaquinoxaline, and lincomycin-spectinomycin were moderately effective. Drugs that were not effective included chlortetracycline, tylosin-sulfamethazine, fosfomycin, furazolidone, nihydrazone, penicillin, bacitracin, and erythromycin. Six antibiotics were tested parenterally against experimental PA infection in another series of experiments. A single dose of an antibiotic was injected subcutaneously 5 to 6 hr after infection except in one experiment in which treatment was delayed until 24 hr after infection. When given 5 to 6 hr after infection, lincomycin-spectinomycin, penicillin-streptomycin, penicillin, oxytetracycline, and spectinomycin significantly reduced mortality. Gentamicin tested under the same conditions was ineffective. Drugs injected 24 hr after infection were not effective.