LAUSR

Four sequence type 664 (ST664) (serotype O:5) strains of Pseudomonas aeruginosa that were highly resistant to antibiotics, including ceftolozane-tazobactam and ceftazidime-avibactam, but were susceptible to colistin were found to harbor the gene encoding the rare class C β-lactamase PAC-1 on a chromosomally located Tn1721-like transposon. The blaPAC-1 gene was associated with the 16S rRNA methylase determinant rmtF2, which confers pan-aminoglycoside resistance. ABSTRACT Four sequence type 664 (ST664) (serotype O:5) strains of Pseudomonas aeruginosa that were highly resistant to antibiotics, including ceftolozane-tazobactam and ceftazidime-avibactam, but were susceptible to colistin were found to harbor the gene encoding the rare class C β-lactamase PAC-1 on a chromosomally located Tn1721-like transposon. The blaPAC-1 gene was associated with the 16S rRNA methylase determinant rmtF2, which confers pan-aminoglycoside resistance. These genotypically related strains were isolated in repatriated patients from Mauritius and Afghanistan and were close to a lineage reported in Nepal, Pakistan, and India.