Emergence of KPC-producing <i>Pseudomonas aeruginosa</i> in Spain: insights into an outbreak and resistance to the novel carbapenem/β-lactamase inhibitor combinations imipenem/relebactam and meropenem/vaborbactam

We report an outbreak of KPC-producing <i>Pseudomonas aeruginosa</i> in Spain, involving four patients and an environmental isolate recovered from a hospital sink. All isolates belonged to clone ST253 and exhibited difficult-to-treat resistance, including resistance to imipenem/relebactam and meropenem/vaborbactam. Genomic analysis confirmed a plasmid-encoded <i>bla</i>_KPC-2 and OprD deficiency. Functional assays demonstrated synergy between KPC-2 production and porin loss on resistance to carbapenem/β-lactamase inhibitors. The findings highlight the clinical threat posed by KPC-producing <i>P. aeruginosa</i>.