CHARACTERIZATION OF THE PLASMID MEDIATED BETA-LACTAMASE BIL-1

A multi-resistant strain of Escherichia coli isolated from a patient from Pakistan was shown to possess a new plasmid-mediated β-lactamase. This enzyme, designated BIL-1, conferred resistance to extended-spectrum cephalosporins such as cefotaxime and ceftazidime. However, unlike other plasmid-mediated β-lactamases capable of conferring resistance to these drugs, the BIL-1 was not a member of the TEM or SHV group of plasmid-mediated β-lactamases and it also conferred resistance to β-lactam drugs in combination with β-lactamase inhibitors (i.e. clavulanic acid). The biochemical properties of the enzyme suggest that BIL-l is related to the Richmond & Sykes Class I chromosomal β-lactamases. Its inhibition properties by various β-lactam drugs are similar to the inhibition properties of the chromosomally encoded P99 enzyme of Enterobacter cloacae. © 1992 The British Society for Antimicrobial Chemotherapy.