Unusual tazobactam-sensitive AmpC β-lactamase from two Escherichia coli isolates

Gioia S. Babini, Franck Danel, Susan D. Munro, Patricia A. Micklesen, David Livermore*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Two Escherichia coli isolates were studied. MIC patterns and hydrolysis assays suggested that they hyperproduced AmpC β-lactamase, but synergy between ceftazidime and tazobactam was greater than between ceftazidime and Ro 48-1256, whereas the converse pattern is typical of AmpC hyperproducers. Studies with purified β-lactamase from one of the isolates confirmed that tazobactam was a 100-fold stronger inhibitor than for the classical E. coli AmpC enzyme. Moreover, in contrast to typical AmpC types, the new enzyme had greater affinity for cephaloridine than for benzylpenicillin.

Original languageEnglish
Pages (from-to)115-118
Number of pages4
JournalJournal of Antimicrobial Chemotherapy
Issue number1
Publication statusPublished - Jan 1998


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