Through a preliminary in vitro screening of a library of 100 molecules, the researchers identified the main structural characteristics needed for the inhibition of the quorum sensing that represents the “language” made of chemical signals used by bacterial species, such as Pseudomonas aeruginosa (Pa), to communicate with each other. The researchers then interrogated FDA libraries of drugs already approved for other therapeutic approaches and identified two compounds, Azaperone and MK-8245, as the most active in reducing virulence factors in P. aeruginosa. Indeed, the two compounds damped the ability of the bacterium in invading the host and in producing biofilm. Interestingly, the compounds also counteracted Pa infection in Gallera mellonella, an insect used as an experimental model to test antimicrobial compounds. The researchers confirmed the antivirulence effects of the compounds in 23 clinical isolates of P. aeruginosa obtained from patients with cystic fibrosis. The obtained results validated the use of already approved drugs as quorum sensing inhibitors active in Pa and provided insights into ready-to-use treatments for lung infections in cystic Fibrosis.