Transferable resistance to imipenem in hospital isolates of Pseudomonas aeruginosa.

We monitored systematically, for more than five years, the eventual transferability of resistance to imipenem in strains of Pseudomonas aeruginosa isolated from patients in Frankfurt University Clinics. Quite recently, four strains have been found which transfer resistance to imipenem to recipient strains of P. aeruginosa. Although in three strains imipenem was the only antibiotic where resistance was transferred directly, the indirect selection analysis showed that, in each instance, determinants of resistance to carbenicillin and kanamycin were co-transferred. The situation in the fourth strain was more complicated. It was resistant to at least ten antipseudomonad antibiotics, and transferred directly not only determinants of resistance to imipenem, but also to carbenicillin and kanamycin, as did the other strains, plus determinants of resistance to ceftazidime and cefotaxime. The origin and mode of spread of resistance determinants in studied strains is briefly discussed.