Experimental Studies on Mice Subcutaneously Challenged with Heat-Killed Cells of Pseudomonas aeruginosa

Abstract

Summary

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 × 10¹⁰ 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 × 10⁹ from 3.4 × 10¹⁰ cells.

However, both methotrexate and actinomy-cin D decreased the incidence of the black lesions.

This investigation was supported by the Office of Naval Research Grant No. N-00014-69-0235, the National Science Foundation graduate traineeship Grant No. GZ 2033, and the National Institutes of Health general research support Grant No. 5 S01 RR05384.