[Comparison of the frequency of imi-r resistant Pseudomonas aeruginosa mutants generated by infection of the bacteria with various bacteriophage-transposons].

We compared the frequencies of imipenem-resistant (imi-r) mutants of a Pseudomonas aeruginosa laboratory strain PAO1 infected by the phages-transposons (PT) specific for this pseudomonad species. The frequency of imi-r mutants among the lysogenic bacteria that appeared after infection reflects the frequency of integrative (conserved) PT transposition into ompD2 gene responsible for synthesis of porin, the protein required for the passage of antibiotic through the cell membrane. After infection by either PT the proportion of imi-r mutants among the lysogenic bacteria was higher than that of spontaneous mutants. The imi-r mutants induced by PT infection form colonies that differ in morphology when grown on different media. The frequencies of imi-r mutants induced by all PT are similar, except for HW12, PM57, and PM62 assigned to a species of the group B3. The phages of this species induce imi-r mutants at a high frequency. Variations in frequencies and colony morphology of imi-r mutants are discussed.