Longevity of Bact. Tularense in Muscle Tissue

Abstract

As the result of investigations carried out by Francis, it has become customary to test for the presence of Bact. tularense in animals dead from tularemia by the injection of a suspension of liver or spleen into guinea pigs. Francis 1 has pointed out that Bact. tularense gradually disappears from the liver and spleen of animals dead from tularemia. He 2 has demonstrated that Bact. tularense in spleen tissue may be kept viable 30 days or longer by storage in 50% glycerine at ice-box temperature. He states that liver is inimical to the life of the infection and, when stored in glycerine with spleen, will destroy the infectivity of the spleen tissue. In his investigation of rabbit livers from the Washington Market, Francis 3 found Bact. tularense viable in rabbits shipped from Tennessee, but the lapse of time after death was unknown.

We have investigated the longevity of Bact. tularense in the liver and spleen of animals dead from experimental tularemia and have gathered comparative data with respect to the longevity of the organism in muscle tissue. Tissues from one guinea pig and 2 rabbits were injected at intervals into 142 guinea pigs used as test animals.

Test No. 1. The carcass of a guinea pig dead from experimental tularemia 4 days after inoculation was kept at room temperature (ca. 20°C). The spleen and liver were thickly studded with necrotic areas. At intervals portions of the liver and spleen of approximately the same size were removed and emulsified in normal saline solution. The suspensions were immediately injected subcutaneously into guinea pigs. The results are shown in Table I.