Emergence of KPC-31, a KPC-3 Variant Associated with Ceftazidime-Avibactam Resistance, in an Extensively Drug-Resistant ST235 Pseudomonas aeruginosa Clinical Isolate.

A ceftazidime-avibactam-resistant KPC-producing Pseudomonas aeruginosa strain was isolated in Argentina from a tracheal aspirate. The patient was treated with ceftazidime-avibactam in combination with other agents for 130 days. Whole-genome sequencing of P. aeruginosa identified a D179Y substitution in the Ω loop of KPC-3, corresponding to KPC-31, integrated at the chromosome. The strain belonged to the sequence type 235/O11 (ST235/O11) high-risk clone. Evaluation of carbapenemase detection assays most used by clinical laboratories failed to identify the isolate as a KPC producer.