A Latent Pneumotropic Pasteurella of Laboratory Animals

Abstract

In the course of attempts to adapt to Swiss mice an agent causing minor respiratory illness in man, pneumonic lesions were encountered in animals inoculated intranasally with mouse-lung material in serial passage. Some animals showed only a transient illness, others died. In smears from consolidated lung areas of these, short rods staining red by Machiavello method and poorly by the Gram method were found. A short, coccoid, bipolar, Gram-negative rod was cultured on simple media. Close relationship between this organism and Pasteurella was suggested. At first, the disease could be reproduced by intra-nasal administration of infected lung tissue only. In the 14th serial animal passage, 85% of the mice died. Pasteurella recovered from these animals, instilled intranasally (undiluted 18-hr, broth), caused bronchopneumonia in 21-day old mice which resulted in death within 2-5 days. A survey of breeding colonies of 4 laboratories indicates that similar organisms could be recovered from the lungs of a large proportion of Swiss mice, guinea pigs, and white rats. Biochemical and morphological studies supported the belief that this organism is one of the Pasteurella group. Serol. study of 26 strains showed them to belong to one group with only minor antigenic differences between strains, and distinct from related organisms. Streptomycin cured infected animals and prevented transfer of the infection in serial passage of lung material.