Ceftazidime and aztreonam resistance in Providencia stuartii: Characterization of a natural TEM-derived extended-spectrum β-lactamase, TEM-60

Abstract

A plasmid-encoded β-lactamase produced from a clinical strain of Providencia stuartii has been purified and characterized. The gene coding for the β-lactamase was cloned and sequenced. It appears to be a new natural TEM-derived enzyme, named TEM-60. Point mutations (Q39K, L51P, E104K, and R164S) are present with respect to the TEM-1 enzyme; the mutation L51P has never been previously reported, with the exception of the chromosomally encoded extended-spectrum β-lactamase PER-I. Kinetic parameters relative to penicillins, cephalosporins, and monobactams other than mechanism-based inactivators were related to the in vitro susceptibility phenotype.