Abstract
In connection with an investigation to determine the etiological agent responsible for a pandemic disease of rabbits 1 , filtration experiments were conducted, and all filter candles were tested in the usual manner with a strain of Serratia marcescens (Bacillus prodigiosus) obtained from Institute stocks. As the work progressed, a fortuitous observation led to an investigation of the pathogenicity of this organism. The growth from a 24 hour agar slant was suspended in 10 cc. of Locke's solution, and rabbits and mice were injected with this material. Rabbits receiving 0.3 cc. intra-cerebrally, or 1.0 cc. intraperitoneally, intravenously, or intrates-ticularly, all died within 24 hours, and all mice injected with 0.6 cc. intraperitoneally or 0.05 cc. intracerebrally also died within 24 hours. A benign course attended the use of smaller amounts of the organism.
The gross findings at autopsy were striking. Hemorrhagic peritonitis with effusion, punctate hemorrhages in the adrenals, hemorrhagic lymph nodes, and small areas of focal necrosis in the liver were constant findings. An occasional animal had consolidated patches in the lungs. The spleen was usually large and swollen. Bacillus prodigiosus was recovered in pure culture from the brain, liver, spleen, lymph nodes, kidneys, lung, and blood.
A second strain of the organism was obtained from another laboratory. Morphologically and culturally it was identical with our own strain. When injected into animals in the large doses previously mentioned, it too caused death in less than 24 hours, and the same pathological picture was present.
Bertarelli 2 reported the death of rats, guinea pigs, and mice following the inoculation of massive doses of Bacillus prodigiosus.
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