TEM-72, a new extended-spectrum beta-lactamase detected in Proteus mirabilis and Morganella morganii in Italy

Abstract

A new natural TEM-2 derivative, named TEM-72, was identified in a Proteus mirabilis strain and in a Morganella morganii strain isolated in Italy in 1999. Compared to TEM-1, TEM-72 contains the following amino acid substitutions: Q39K, M182T, G238S, and E240K. Kinetic analysis showed that TEM-72 exhibits an extended-spectrum activity, including activity against oxyimino-cephalosporins and aztreonam. Expression of bla(TEM-72) in Escherichia coli was capable of decreasing the host susceptibility to the above drugs.

FIG. 1

(A) Agarose gel electrophoresis of the plasmid pPM14, purified from P. mirabilis FI-14. Lanes: U, uncut; H, B, R, V, P, after digestion with HindIII, BglII, EcoRI, EcoRV, and PstI, respectively. (B) Results of Southern blot analysis of the gel shown in panel A using the bla_TEM probe. DNA size standards (in kilobase pairs) are shown on the left. Identical results were obtained with plasmid pMN-13 purified from M. morganii FI-13 and with plasmids purified from the respective E. coli transformants.