EXPERIMENTAL STUDIES ON THE SIGNIFICANCE OF ENDOTOXIN IN THE PATHOGENESIS OF BRUCELLOSIS

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Abstract
The somatic antigen, or endotoxin, from smooth cultures of Brucella organisms was prepared according to the method of Boivin and the lethal activity of the material was detd. with a strain of ABC white male mice. It was observed that regardless of the invasiveness and virulence of the living Brucella cells, the lethal action of the endotoxin was of the same degree for all strains of Brucella, which included the 3 different spp., provided that smooth cultures were used in the prepn. of the material. Cortisone protected the animals against the lethal action of the endotoxin, but pretreatment or simultaneous therapy with antibiotics had no effect on the outcome. The admn. of thorotrast abetted the action of the endotoxin. The fact that the endotoxin from a strain of Br. abortus of low virulence was just as lethal as the endotoxin from a highly invasive strain of Br. melitensis, suggested that the toxemia exhibited in the acute phase of human brucellosis was related to the activity of liberated somatic antigen. It was postulated that if the human host permitted the rapid multiplication of the less virulent strains of Brucella, such as strain 19 of Br. abortus, the toxemia might be just as severe as seen in patients infected with a highly invasive strain of Br. melitensis. Human disease due to strain 19 rarely occurs, but a severe state of toxemia was observed in a young adult male from whose blood strain 19 was cultured. A similar relationship between toxicity and the somatic antigen probably occurs with other gram-negative spp., particularly typhoid fever.