[Effect of plasmids on the virulence of Pseudomonas aeruginosa strains in experiments on mice].

A comparative study of virulence of P. aeruginosa strains PAO containing and not containing plasmids has been made. A number of plasmids which are present in strains PAO decrease their virulence for mice 3-7 times. The virulence-affecting plasmids considerably differ in their biological properties. Bacterial mutations rpm, selected as mutations stabilizing RP4 plasmid in PAO cells, have also been found to affect virulence of bacteria, decreasing its level several times. The introduction of plasmids into PAO cells carrying mutations rpm is not accompanied by decrease of virulence.