Virulence of Pseudomonas aeruginosa and spontaneous spread of pseudomonas pneumonia in a mink ranch.

Comparative studies on the virulence of two strains of Pseudomonas aeruginosa isolated from otic pus and mink pneumonic lesion, respectively, were made by means of intranasal inoculation in mink. The minimal lethal dose of the former (strain NC-5, highly virulent for mice) was 10(10), and that of the latter (strain No. 5, moderately virulent for mice) was 5.5 x 10(6). By planting droplets of P. aeruginosa suspension on the mink in the wire cages, an enzootic lethal pneumonia was brought about in a ranch. This disease spread to the neighboring 12 mink in turn, in one direction, with new cases occurring every day or every other day for 13 days.