Abstract: A pharmaceutical formulation comprises, in combination with a penem of formula (I): in which: R1 is hydrogen or an organic substituent group; R2 is a fused bicyclic heterocyclic ring system of general formula:  wherein R4 and R5 are independently hydrogen or one or more substituents replacing hydrogen atoms in the ring system shown; m is 2 or 3; p is zero, 1 or 2; and R3 is hydrogen, a salt-forming cation or an ester-forming group; and the symbol ═/═ indicates that the double bond may be in either the E or Z configuration; and a pharmaceutically acceptable carrier; a &bgr;-lactam antibiotic selected from the group consisting of ceftazidime, cefotaxime, amoxycillin, and piperacillin, and pharmaceutically acceptable derivatives thereof.

Abstract: Pharmaceutical formulations comprising ceftriaxone in combination with a penem of formula (I) in which R.sup.1 is hydrogen or an organic group; R.sup.2 is a ring system of formula (II), wherein R.sup.4 and R.sup.5 are hydrogen or one or more substituents; m is 2 or 3; p is 0, 1 or 2; R.sup.3 is hydrogen, a pharmaceutically acceptable salt-forming cation or a pharmaceutically acceptable in-vivo hydrolysable ester-forming group; and with a pharmaceutically acceptable carrier. The formulations have antibacterial activity, the compound of formula (I) acting as a .beta.-lactamase inhibitor.

Abstract: A pharmaceutical formulation comprises, in combination with a penem of formula (I): ##STR1## in which: R.sup.1 is hydrogen or an organic substituent group;R.sup.2 is a fused bicyclic heterocyclic ring system of general formula: ##STR2## wherein R.sup.4 and R.sup.5 are independently hydrogen or one or more substituents replacing hydrogen atoms in the ring system shown; m is 2 or 3; p is zero, 1 or 2; and R.sup.3 is hydrogen, a salt-forming cation or an ester-forming group; and the symbol =/= indicates that the double bond may be in either the E or Z configuration; and a pharmaceutically acceptable carrier; a .beta.-lactam antibiotic selected from the group consisting of ceftazidime, cefotaxime, amoxycillin, and piperacillin, and pharmaceutically acceptable derivatives thereof.

Abstract: A pharmaceutical formulation comprises, in combination with a penem of formula (I), in which: R.sup.1 is hydrogen or an organic substituent group; R.sup.2 is a fused bicyclic heterocyclic ring system of general formula (a), wherein R.sup.4 and R.sup.5 are independently hydrogen or one or more substituents replacing hydrogen atoms in the ring system shown; m is 2 or 3; p is zero, 1 or 2; and R.sup.3 is hydrogen, a salt-forming cation or an ester-forming group; and the symbol .dbd./.dbd. indicates that the double bond may be in either the E or Z configuration; and a pharmaceutically acceptable carrier, a .beta.-lactam antibiotic selected from the group consisting of ceftazidime, cefotaxime, amoxycillin, and piperacillin, and pharmaceutically acceptable derivatives thereof.

Abstract: A pharmaceutical formulation comprises, in combination with a penem of formula (I): ##STR1## in which: R.sup.1 is hydrogen or an organic substituent group;R.sup.2 is a fused bicyclic heterocyclic ring system of general formula: ##STR2## wherein R.sup.4 and R.sup.5 are independently hydrogen or one or more substituents replacing hydrogen atoms in the ring system shown; m is 2 or 3; p is zero, 1 or 2; and R.sup.3 is hydrogen, a salt-forming cation or an ester-forming group; and the symbol .dbd./.dbd. indicates that the double bond may be in either the E or Z configuration; and a pharmaceutically acceptable carrier; a .beta.-lactam antibiotic selected from the group consisting of ceftazidime, cefotaxime, amoxycillin, and piperacillin, and pharmaceutically acceptable derivatives thereof.