A combination of a compound of Formula I: or a pharmaceutically acceptable salt thereof, wherein: X is: CH 2, CH 2 CH 2, or CH 2 CH 2 CH2; R 1 is C N(R 3)R 4, R 2 is SO 3 M, OSO 3 M, SO 2 NH 2, PO 3 M, OPO 3 M, CH 2 CO 2 M, CF 2 CO 2 M, or CF 3; M is H or a pharmaceutically acceptable cation; R3 is Het A; R 4 is H or C 1-8 alkyl optionally substituted with N(R A)R B; or alternatively R 3 and R 4 together with the N atom to which they are both attached form a 4- to 9-membered, saturated monocyclic ring optionally containing 1 heteroatom in addition to the nitrogen attached to R 3 and R 4 selected from N, O, and S, where the S is optionally oxidized to S or S 2; wherein the monocyclic ring is optionally fused to, bridged with, or spiro to a 4- to 7-membered, saturated heterocyclic ring containing from 1 to 3 heteroatoms independently selected from N, O and S, where the S is optionally oxidized to S or S 2, to form a bicyclic ring system, wherein the monocyclic ring or the bicyclic ring system so formed is optionally substituted with 1 or 2 substituents each of which is independently: C 1-6 alkyl, C 1-6 fluoroalkyl, (CH 2) 1-2 G wherein G is OH, O-C 1-6 alkyl, O-C 1-6 fluoroalkyl, N(R A)R B, C N(R A)R B, C R A, CO 2 R A, or SO 2 R A, O-C 1-6 alkyl, O-C 1-6 fluoroalkyl, OH, oxo, halogen, N(R A)R B, C N(R A)R B, C R A, C -C 1-6 fluoroalkyl, C OR A, or S 2 R A; HetA is a 4- to 9-membered saturated or mono-unsaturated heterocyclic ring containing from 1 to 3 heteroatoms independently selected from N, O and S, wherein any ring S is optionally oxidized to S or S 2 and either 1 or 2 ring carbons are optionally oxidized to C; wherein the ring is optionally fused with a C 3-7 cycloalkyl; and wherein the optionally fused, saturated or mono-unsaturated heterocyclic ring is optionally substituted with a total of from 1 to 4 substituents selected from zero to 2 (CH 2) n N(R A)R B and zero to 2 (CH 2) n R C; each n is independently an integer which is 0, 1, 2, or 3; each R A is independently H or C 1-8 alkyl; each R B is independently H or C 1-8 alkyl; each RC is independently C 1-6 alkyl, OH, O-C 1-8 alkyl, OC -C 1-8 alkyl, C(=NH)NH 2, NH-C(=NH)NH 2, halogen, CN, C R A, C OR A, C N(R A)R B, SO 2 R A, SO 2 N(R A)R B, pyridyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, or thiomorpholinyl; and a carbapenem antibiotic. X is: CH 2, CH 2 CH 2, or CH 2 CH 2 CH2; CH 2, CH 2 CH 2, or CH 2 CH 2 CH2; R 1 is C N(R 3)R 4, R 2 is SO 3 M, OSO 3 M, SO 2 NH 2, PO 3 M, OPO 3 M, CH 2 CO 2 M, CF 2 CO 2 M, or CF 3; M is H or a pharmaceutically acceptable cation; R3 is Het A; R 4 is H or C 1-8 alkyl optionally substituted with N(R A)R B; or alternatively R 3 and R 4 together with the N atom to which they are both attached form a 4- to 9-membered, saturated monocyclic ring optionally containing 1 heteroatom in addition to the nitrogen attached to R 3 and R 4 selected from N, O, and S, where the S is optionally oxidized to S or S 2; wherein the monocyclic ring is optionally fused to, bridged with, or spiro to a 4- to 7-membered, saturated heterocyclic ring containing from 1 to 3 heteroatoms independently selected from N, O and S, where the S is optionally oxidized to S or S 2, to form a bicyclic ring system, wherein the monocyclic ring or the bicyclic ring system so formed is optionally substituted with 1 or 2 substituents each of which is independently: C 1-6 alkyl, C 1-6 fluoroalkyl, (CH 2) 1-2 G wherein G is OH, O-C 1-6 alkyl, O-C 1-6 fluoroalkyl, N(R A)R B, C N(R A)R B, C R A, CO 2 R A, or SO 2 R A, O-C 1-6 alkyl, O-C 1-6 fluoroalkyl, OH, oxo, halogen, N(R A)R B, C N(R A)R B, C R A, C -C 1-6 fluoroalkyl, C OR A, or S 2 R A; HetA is a 4- to 9-membered saturated or mono-unsaturated heterocyclic ring containing from 1 to 3 heteroatoms independently selected from N, O and S, wherein any ring S is optionally oxidized to S or S 2 and either 1 or 2 ring carbons are optionally oxidized to C; wherein the ring is optionally fused with a C 3-7 cycloalkyl; and wherein the optionally fused, saturated or mono-unsaturated heterocyclic ring is optionally substituted with a total of from 1 to 4 substituents selected from zero to 2 (CH 2) n N(R A)R B and zero to 2 (CH 2) n R C; each n is independently an integer which is 0, 1, 2, or 3; each R A is independently H or C 1-8 alkyl; each R B is independently H or C 1-8 alkyl; each RC is independently C 1-6 alkyl, OH, O-C 1-8 alkyl, OC -C 1-8 alkyl, C(=NH)NH 2, NH-C(=NH)NH 2, halogen, CN, C R A, C OR A, C N(R A)R B, SO 2 R A, SO 2 N(R A)R B, pyridyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, or thiomorpholinyl; and a carbapenem antibiotic.