Nosocomial Outbreak of Carbapenem-Resistant Pseudomonas aeruginosa with a New bla(IMP) Allele, bla(IMP-7)

Pseudomonas aeruginosa isolates from an outbreak in Canada were highly resistant to carbapenems and ceftazidime but not piperacillin. They produced a novel integron-associated metallo-β-lactamase, designated IMP-7, with 91% identity to IMP-1. bla(IMP-7) was not detected with standard bla(IMP)-specific primers, owing to mismatches in the forward primer.