Experimental Studies upon B. violaceous,Isolated from a Fulminating Fatal Human Infection. ∗

Bacillus violaceous (Chromobacterium violaceum) is considered a common saprophytic microorganism occurring in soil, water, sewage and contaminated food. It is generally regarded as non-pathogenic for man and lower animals.

Woolley 1 reported fatal infections of caribao in Manila with this microorganism which resembled hemorrhagic septicemia of cattle. He also established the pathogenicity of the isolated culture but did not find evidence of toxin-production. Recently Black and Shahan 2 and Soule 3 reported instances of human infection with B. violaceous which persisted for many months and finally proved fatal. Soule demonstrated pathogenicity for laboratory animals.

The culture employed in the present experiments was isolated in pure state on ordinary media from the lesions present in various organs at the necropsy of a human case. The infection arose from a wound of the foot. There ensued a marked inguinal adenitis∗ septicemia, as shown by a positive blood culture, and death within a week.

Studies of pathogenicity and animal protection have been performed with this culture.

Pathogenicity Experiments. 12 rabbits, 10 guinea pigs and 12 white mice were employed. Six rabbits received intravenously 1 cc of a saline suspension containing approximately one billion microorganisms per cc. The suspension was made from the growth of B. violaceous on nutrient agar. All 6 animals died in approximately 24 hours. The necropsies showed no macroscopical lesions. Cultures of B. violaceous were recovered from the lungs, liver, spleen, and heart's blood. The microscopical study of sections revealed degenerative changes, particularly in the liver.

Six rabbits were injected intraäbdominally with a broth culture of B. violaceous in amounts of .5 cc, 0.75 cc, 1 cc, 1.25 cc, 1.5 cc, and 2 cc. Those receiving 2 cc and 1.5 cc died in 12 hours and 24 hours respectively.