Identification of New Natural CphA Metallo-β-Lactamases CphA4 and CphA5 in Aeromonas veronii and Aeromonas hydrophila Isolates from Municipal Sewage in Central Italy

Abstract

Two new natural CphA metallo-β-lactamases, the CphA4 and CphA5 enzymes, were identified in water samples from municipal sewage in central Italy. Compared to CphA, the CphA4 and CphA5 enzymes showed numerous point mutations. These enzymes have a narrow spectrum of substrates focused on carbapenems only. CphA5 showed kcat values about 40-, 12-, and 97-fold higher than those observed for CphA4 versus imipenem, ertapenem, and biapenem, respectively.