A crystalline compound of formula (I): ##STR00001## The compound of formula (I) is a β-lactamase inhibitor and may be administered in combination with an antibacterial agent for prevention or treatment of bacterial infection.

A crystalline compound of formula (I): ##STR00001## The compound of formula (I) is a β-lactamase inhibitor and may be administered in combination with an antibacterial agent for prevention or treatment of bacterial infection.

Novel iron chelating group conjugated penam derivatives described herein show antibacterial activity, and could be used as antibacterial agents or beta-lactamase inhibitors (BLIs) which are of value for application in combination with other antibacterial agents. ##STR00001##

Novel iron chelating group conjugated penam derivatives described herein show antibacterial activity, and could be used as antibacterial agents or beta-lactamase inhibitors (BLIs) which are of value for application in combination with other antibacterial agents. ##STR00001##

Novel iron chelating group conjugated penam derivatives described herein show antibacterial activity, and could be used as antibacterial agents or beta-lactamase inhibitors (BLIs) which are of value for application in combination with other antibacterial agents.

##STR00001##

Novel iron chelating group conjugated penam derivatives described herein show antibacterial activity, and could be used as antibacterial agents or beta-lactamase inhibitors (BLIs) which are of value for application in combination with other antibacterial agents.

##STR00001##

A crystalline compound of formula (I):

##STR00001##

The compound of formula (I) is a -lactamase inhibitor and may be administered in combination with an antibacterial agent for prevention or treatment of bacterial infection.

A crystalline compound of formula (I):

##STR00001##

The compound of formula (I) is a -lactamase inhibitor and may be administered in combination with an antibacterial agent for prevention or treatment of bacterial infection.

Pharmaceutical compositions comprising cefepime or a pharmaceutically acceptable salt thereof, tazobactam or a pharmaceutically acceptable salt thereof, and arginine or a pharmaceutically acceptable salt thereof; and their use in treatment, control or prevention of bacterial infection is disclosed.

Pharmaceutical compositions comprising cefepime or a pharmaceutically acceptable salt thereof, tazobactam or a pharmaceutically acceptable salt thereof, and arginine or a pharmaceutically acceptable salt thereof; and their use in treatment, control or prevention of bacterial infection is disclosed.