Comparative study of Mycoplasma pulmonis and Mycoplasma gallisepticum infections in turkey sinus.

Infraorbital sinuses of young turkeys were injected with virulent strains of Mycoplasma pulmonis and Mycoplasma gallisepticum to compare the diseases caused by the 2 agents. Mycoplasma pulmonis did not cause visible swelling from large quantities of mucous exudate in the sinuses, such as occurs with M gallisepticum, and it could not be recovered by bacteriologic culture technique after 3 weeks. However, slight exudate did accompany the M pulmonis infection. Similarities between the disease caused by M pulmonis and that caused by M gallisepticum included lymphocytic infiltration in the submucosa, swollen epithelial cells, and loss of cilia from sinus epithelial cell surfaces. This strain of M pulmonis, which is pathogenic for rats, was only mildly pathogenic for turkeys and the infection did not persist for long.