IMP-29, a Novel IMP-Type Metallo-β-Lactamase in Pseudomonas aeruginosa

Analysis of two clonally related multiresistant Pseudomonas aeruginosa isolates led to the identification of a novel IMP-type metallo-beta-lactamase. IMP-29 was significantly different from the other IMP variants (the closest variant being IMP-5 with 93% amino acid identity). The bla(IMP-29) gene cassette was carried by a class 1 integron in strain 10.298, while in strain 10.266 it was located in a rearranged DNA region on a 30-kb conjugative plasmid. Biochemical analysis confirmed that IMP-29 efficiently hydrolyzed carbapenems.