Relebactam and vaborbactam: These drugs block classes A and C but not classes D and B. There are no currently available beta-lactamase inhibitors active against MBLs, such as NDM-1 (New Delhi MBL-1), VIMs (Verona integron-encoded MBLs), and IMP (imipenem) - types, which can inactivate all beta-lactam antibiotics except for aztreonam.