0000000000374355
AUTHOR
Maxime Bour
Mechanisms of Resistance to Ceftolozane/Tazobactam in Pseudomonas aeruginosa : Results of the GERPA Multicenter Study
ABSTRACT Resistance mechanisms of Pseudomonas aeruginosa to ceftolozane/tazobactam (C/T) were assessed on a collection of 420 nonredundant strains nonsusceptible to ceftazidime (MIC > 8 μg/ml) and/or imipenem (>4 μg/ml), collected by 36 French hospital laboratories over a one-month period (the GERPA study). Rates of C/T resistance (MIC > 4/4 μg/ml) were equal to 10% in this population (42/420 strains), and 23.2% (26/112) among the isolates resistant to both ceftazidime and imipenem. A first group of 21 strains (50%) was found to harbor various extended-spectrum β-lactamases (1 OXA-14; 2 OXA-19; 1 OXA-35; 1 GES-9; and 3 PER-1), carbapenemases (2 GES-5; 1 IMP-8; and 8 VIM-2), or both (1 VIM-2…
Acquisition of Class C β-Lactamase PAC-1 by Sequence Type 644 Strains of Pseudomonas aeruginosa
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 Tn 1721 -like transposon. The bla PAC-1 gene was associated with the 16S rRNA methylase determinant rmtF2 , which confers pan-aminoglycoside resistance.