A PRELIMINARY-STUDY ON THE PATHOGENICITY OF BACILLUS-LICHENIFORMIS BACTERIA IN IMMUNODEPRESSED MICE

The pathogenicity of 13 strains of Bacillus licheniformis was studied in immunodepressed mice. The strains had been isolated from cases of b ovine abortions (n=5), bovine feedstuffs (n=3), soil (n=l), and grain products (n=2). The origin of two strains was unknown. Groups of 10 mi ce were inoculated intravenously with B. licheniformis bacteria at dos es from <10(6) to 10(10) colony-forming units. Following 7 days of inf ection, the animals were euthanized and examined bacteriologically, hi stologically, and immunohistochemically using a PAP technique based on primary polyclonal rabbit anti-B. licheniformis antibodies. B. lichen iformis bacteria were reisolated from the liver, spleen, or kidneys of mice in all groups. Inflammatory lesions were present in mice of all immunodepressed groups, but only brain and pulmonic lesions were defin itely attributed to B. licheniformis infection, as strong immunostaini ng was found within these lesions. It is concluded that all strains of B, licheniformis examined were pathogenic for immunodepressed mice, a nd that spontaneous infections may be established by bacterial strains to which susceptible individuals are accidentally exposed.