Transduction of resistance to Imipenem, Aztreonam and Ceftazidime in nosocomial strains of Pseudomonas aeruginosa by wild-type phages.

Two wild-type bacteriophages, designated AP-2 (for P. aeruginosa phage) and AP-12, have been isolated and propagated from two multiple drug resistant strains of P. aeruginosa. Both phages were found to transduce Imipenem- (IMI), Aztreonam- (AZA) and Ceftazidime- (CTZ) resistance as well as resistance determinants to other drugs. Genetic analysis showed that resistance determinants to newest anti-pseudomonal antibiotics IMI, AZA and CTZ could be separated by transduction. Thus the resistance to these antibiotics is presumably coded by different genes. In some transductans also the presence of the tra+ has been demonstrated, indicating that they can transfer the resistance to other strains by conjugation.