The present invention relates to the compound (E,Z)-ajoene of formula (1) for use in treatment of bacterial infections. Another aspect of the present invention is a composition comprising (E,Z)-ajoene of formula (1) and at least one antibiotic. Yet another aspect of the invention relates to a method for manufacturing (E,Z) ajoene of formula (1) wherein the conformation of the internal C=C- bond can be either E or Z or a mixture thereof, said method comprising reacting allicin of formula (3) with an acid in the presence of a solvent to provide (E,Z ajoene) of formula (1) as defined above. Yet another aspect of the invention is (E,Z)-ajoene of formula 1 obtainable by the method described above.