Characterization of TEM-56, a Novel β-Lactamase Produced by a Klebsiella pneumoniae Clinical Isolate

TEM-56 produced by a Klebsiella pneumoniae clinical isolate is a novel β-lactamase of isoelectric point 6.4 that confers a moderate resistance level to expanded-spectrum cephalosporins. The amino acid sequence deduced from the corresponding bla gene showed two amino acid replacements with respect to the TEM-2 sequence: Glu-104 to Lys and His-153 to Arg. This enzyme showed catalytic properties close to those of TEM-18. Thus, TEM-56 appears as a new TEM mutant, an intermediary between TEM-18 and the extended-spectrum β-lactamase TEM-21.