[A novel extended-spectrum beta-lactamase in a ceftazidime-resistant isolate of E. coli].

A novel extended-spectrum beta-lactamase (ESbla) encoded on a plasmid of approximately 7.5kb, conferring resistance to beta-lactams tested except cefoxitin and imipenem, was found in a ceftazidime-resistant isolate of E. coli form our hospital. The resistance to beta-lactams was transferred by conjugation to E. coli JP559 together with the aminoglycosides and sulfonamide resistance. Clavulanate, one of beta-lactamase inhibitors, inhibited its activity. This ESbla gene hybridized neither with an intra-genic fragment of SHV-1 nor with that of TEM-1. The molecular origin of that novel ESbla needed to be further studied.