Experimental studies on mice subcutaneously challenged with heat-killed cells of Pseudomonas aeruginosa.

Mice were found to be generally refractory to sc challenge with heat-killed cells of Pseudomonas aeruginosa and did not die unless unusually high concentrations were employed. Approximately 38.6% of the animals receiving a single, sublethal dose of 1 X 10(10) dead cells developed black, crusty, necrotic skin lesions within 3 to 5 days. No major gross and histopathological changes were detected in internal organs. If the animals were sc administered sublethal doses of either live or dead cells of P aeruginosa 16 days prior to sc challenge, then the incidence of black lesions rose to 78.6 and 50% of the animals, respectively. Of several antineoplastic agents tested, only methotrexate significantly affected the 72-hr LD50 resulting in a drop to 1.8 X 10(9) afrom 3.4 X 10(10) cells. However, both methotrexate and actinomycin D decreased the incidence of the black lesions.