The present invention is directed to an acyl homoserine lactone and catalase conjugate wherein the acyl homoserine lactone is N-3-(oxododecanoyl)-L-homoserine lactone (OdDHL) or butyryl L-homoserine lactone (BHL) and the catalase is a P. aeruginosa KatA protein or an antigenic portion thereof. The conjugate is used to treat P. aeruginosa infections by limiting the formation of biofilms and inhibiting a range of quorum-sensing dependent virulence factors by having an immunogenic conjugate provided as a therapeutic or prophylactic vaccine.
