Antibiotics at sub-inhibitory concentrations and virulence factors of Pseudomonas aeruginosa.

The difficulty of instituting an efficacious therapy against Pseudomonas aeruginosa infections is principally due to the microorganism's antibiotic resistance. The aim of our study was to evaluate the activity of four antibacterial drugs, two penems and two quinolones, on the production of virulence factors. Our results demonstrated that the antibiotics tested have a different behaviour depending on the P. aeruginosa phenotype. Therefore it would be advisable to choose the drug on the basis of the isolated strain phenotype.