The present invention relates to metallo-β-lactamase inhibitor compounds of Formula I: and pharmaceutically acceptable salts thereof, wherein Z, RA, X1, X2 and R1 are as defined herein. The present invention also relates to compositions which comprise a metallo-β-lactamase inhibitor compound of the invention or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, optionally in combination with a beta lactam antibiotic and/or a beta-lactamase inhibitor. The invention further relates to methods for treating a bacterial infection comprising administering to a patient a therapeutically effective amount of a compound of the invention, in combination with a therapeutically effective amount of one or more β-lactam antibiotics and optionally in combination with one or more beta-lactamase inhibitor compounds. The compounds of the invention are useful in the methods described herein for overcoming antibiotic resistance.