Busulfan inhibits Pseudomonas aeruginosa growth and reduces biofilm biomass and pyocyanin production

Background: remains a serious threat in clinical settings, especially among patients who are immunocompromised, receiving chemotherapy, or in intensive care units. With the rise of antibiotic resistance, drug repurposing offers a promising alternative strategy. Busulfan, an anticancer alkylating agent that induces DNA cross-linking and cytotoxic effects in cancer cells, may exert similar effects on microorganisms, as reported for other alkylating agents. Methods: . Initially, the antimicrobial activity of busulfan was assessed using the microdilution method, followed by investigations of key virulence factors of the PAO1 strain after treatment. Results: Busulfan inhibited bacterial growth in a dose-dependent manner, with 84% inhibition observed at 108 μg/mL, whereas bactericidal activity was only observed at much higher concentrations (MBC >512 and