Abstract
During the past year, while working with tissues and exudates from patients with rheumatic fever or rheumatoid arthritis, a pleuro-pneumonia-like micro-organism has been encountered in our laboratory mice.
In each instance, normal young white mice of the same breed were inoculated intranasally under ether anesthesia with 0.05 cc of 10–20% tyrode or saline suspensions of human pathologic tissues. However, exudates were introduced without dilution. Serial mouse-passage was carried on at intervals of 4–6 days, using 10–20% lung-suspensions. Blind passages were done in a parallel fashion. Usually by the fourth passage, purple areas of pneumonic consolidation were clearly visible in one or more lobes. In one instance, the pneumonia appeared as early as the second passage. Further passage slowly increased the virulence, morbidity and mortality. Even after months of passage, however, the mortality never increased beyond 20–30%, with death usually occurring on the fourth or fifth day.
Culture of the ground lungs uniformly grew innumerable colonies of a pleuro-pneumonia-like micro-organism. The morphology and nature of this microbe has been described in a previous note. 1 Other bacteria were rarely encountered, and these usually disappeared with the next passage. However, in 2 instances, the mortality was highly increased by the association of a gram negative bacillus.
The infective agent was readily preserved by freezing at — 80°C. It grew nicely on boiled-blood-ascitic agar plates or broth, in as wide a pH range as 7.0 to 7.8. Multiplication occurred in chick-embryo-tyrode tissue-culture medium, 2 or on embryo-tyrode-agar. 3 We were totally unsuccessful in attaining growth upon the chorioallantoic membranes of chick embryos in the standard fashion. However, if the inoculated embryo was chilled to death at 4°C, followed by incubation, growth and serial passage were readily accomplished.
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