A compound selected in the group consisting in (RS)-2,3-bis(sulfanyl)propane-1-sulfonic acid or one of his salts for use in a method of treating a bacterial infection, pharmaceutical compositions comprising (RS)-2,3-bis(sulfanyl)propane-1-sulfonic acid or one of his salts, and a method for inhibiting ß-lactamases of bacteria in warm-blooded animals, comprising administering to warm-blooded animals a ß-lactamase inhibiting effective amount of at least (RS)-2,3-bis(sulfanyl)propane-1-sulfonic acid or one of his salts.