Augmentation of the antimicrobial efficacy of antibiotics by filamentous phage.

A significant increase in sensitivity to several antibiotics was observed in vitro after infection of the two Pseudomonas aeruginosa strains O1 and K with the filamentous phage Pf3 and Pf1, respectively. Moreover, upon infection with phage Pf1 a P. aeruginosa K strain harboring a plasmid-borne gentamicin resistance gene could be resensitized to the antibiotic. We further show that BALB/c mice were rescued from lethal infections with P. aeruginosa K by concomitant treatment with phage Pf1 and low concentrations of gentamicin, neither of which was able to cure the infection when administered alone.