This invention relates to novel substituted succinic acid metallo-null-lactamase inhibitors which are useful potentiators of null-lactam antibiotics. Accordingly, the present invention provides a method of treating bacterial infections in animals or humans which comprises administering, together with a b-lactam antibiotic, a therapeutically effective amount of a compound of formula I: 1 including pharmaceutically acceptable salts, prodrugs, anhydrides, and solvates thereof.