Studies on the efficacy of combined immunostimulant-antibiotic therapy against experimental Mycoplasma gallisepticum infection in chickens.

Josamycin is an antibiotic known to become selectively concentrated intracellularly and in respiratory organs, the habitate of Mycoplasma gallisepticum. The aim of this present work was to evaluate the efficacy of josamycin when given alone or combined with an immunostimulant Cornebacterium cutis ultralysate. Groups of chickens were given josamycin alone or Corynebacterium ultralysate alone or both agents or nothing immediately before induction of Mycoplasma gallisepticum infection. Birds were subjected to pathological examination to evaluate the incidence and severity of air-sacculitis, bacteriological examination for re-isolation of Mycoplasma gallisepticum and for immunological examination to evaluate the humoral immune response to the infection (haemagglutination inhibiting titre determination). The effect of treatments used in this study was to decrease the incidence and severity of air sacculitis. The magnitude of rise in haemagglutination inhibiting titres were greater and faster in birds given Corynebacterium ultralysate. Treatments failed to achieve complete elimination of Mycoplasma. No special advantage was obtained from the use of josamycin, its effects were rather similar to previously used chemotherapy.