A minute, pleomorphic, motile, Gram-negative bacterium has been isolated from two specimens of nodular tissue from human verruga. In films and sections of the original tissues the organism in question is difficult to distinguish from Bartonella bacilliformis, with which it was associated, and even in pure culture it has a number of properties in common with that parasite. No sugars are fermented by it, it is an obligate aerobe, the optimum temperature for its growth is 25°C., and it has two to four spiral flagella attached to one end of the body. It is, however, readily cultivated on any ordinary culture medium. Broth cultures contain much mucin, but no hydrogen sulfide is formed. Coagulated serum is liquefied by its growth, and the red corpuscles in a blood agar plate are hemolyzed.
Rabbits, guinea pigs, rats, and mice develop acute, fatal septicemia as a result of intravenous or intratesticular inoculation of young cultures. The liver is characteristically affected and shows a general parenchymatous degeneration and necrosis; the entire gastrointestinal tract is intensely congested, and numerous hemorrhagic areas are present; the spleen, dark and soft, is rarely much enlarged; the kidneys are swollen and congested; the adrenals are much swollen and intensely red; the lungs are sometimes congested but otherwise normal. In the case of intratesticular inoculation the scrotum and testicle both undergo rapid gangrene. In monkeys no septicemia has been observed, but a violent local reaction—swelling, congestion, sometimes necrosis—follows intradermal inoculation.
Since no microorganism corresponding in character with this one has previously been described, it is regarded as a new species, and because of its presence in material obtained from Peru it has been given the name Bacterium peruvianum. The significance of the association of B. peruvianum with Bartonella bacilliformis deserves further investigation; it is not impossible that the two organisms are introduced into the human body by the same blood-sucking insect.