Imipenem and cefotaxime resistance: transduction by wild-type phages in hospital strains of Pseudomonas aeruginosa.

A wild-type bacteriophage appeared and was isolated from a Pseudomonas aeruginosa strain resistant to imipenem, cefotaxime, kanamycin and streptomycin (susceptible to carbenicillin, aztreonam, amikacin and fluoroquinolones). The best transducing properties were obtained with phage lysates prepared from bacteria growing on cefotaxime or imipenem. Transducing properties were found specific for individual recipient strain(s) susceptible to all drugs. A high-frequency of transduction was recorded for kanamycin and particularly for cefotaxime resistance determinants, followed by an imipenem determinant. This is now the fourth published wild-type bacteriophage, isolated from lysogenic nosocomial P. aeruginosa resistant to imipenem which was found to transduce this resistance determinant to susceptible pseudomonads.