AUTHOR=Soto Katherine D. , Alcalde-Rico Manuel , Ugalde Juan A. , Olivares-Pacheco Jorge , Quiroz Valeria , Brito Bárbara , Rivas Lina M. , Munita José M. , García Patricia C. , Wozniak Aniela 

TITLE=Ceftazidime/avibactam resistance is associated with PER-3-producing ST309 lineage in Chilean clinical isolates of non-carbapenemase producing Pseudomonas aeruginosa

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2024.1410834

DOI=10.3389/fcimb.2024.1410834

ISSN=2235-2988

ABSTRACT=<sec><title>Introduction</title><p>Ceftazidime/avibactam (CZA) is indicated against multidrug-resistant <italic>Pseudomonas aeruginosa</italic>, particularly those that are carbapenem resistant. CZA resistance in <italic>P. aeruginosa</italic> producing PER, a class A extended-spectrum β-lactamase, has been well documented <italic>in vitro</italic>. However, data regarding clinical isolates are scarce. Our aim was to analyze the contribution of PER to CZA resistance in non-carbapenemase-producing <italic>P. aeruginosa</italic> clinical isolates that were ceftazidime and/or carbapenem non-susceptible.</p></sec><sec><title>Methods</title><p>Antimicrobial susceptibility was determined through agar dilution and broth microdilution, while <italic>bla</italic><sub>PER</sub> gene was screened through PCR. All PER-positive isolates and five PER-negative isolates were analyzed through Whole Genome Sequencing. The mutational resistome associated to CZA resistance was determined through sequence analysis of genes coding for PBPs 1b, 3 and 4, MexAB-OprM regulators MexZ, MexR, NalC and NalD, AmpC regulators AmpD and AmpR, and OprD porin. Loss of <italic>bla</italic><sub>PER-3</sub> gene was induced in a PER-positive isolate by successive passages at 43°C without antibiotics. </p></sec><sec><title>Results</title><p>Twenty-six of 287 isolates studied (9.1%) were CZA-resistant. Thirteen of 26 CZA-resistant isolates (50%) carried <italic>bla</italic><sub>PER</sub>. One isolate carried <italic>bla</italic><sub>PER</sub> but was CZA-susceptible. PER-producing isolates had significantly higher MICs for CZA, amikacin, gentamicin, ceftazidime, meropenem and ciprofloxacin than non-PER-producing isolates. All PER-producing isolates were ST309 and their <italic>bla</italic><sub>PER-3</sub> gene was associated to ISCR1, an insertion sequence known to mobilize adjacent DNA. PER-negative isolates were classified as ST41, ST235 (two isolates), ST395 and ST253. PER-negative isolates carried genes for narrow-spectrum β-lactamases and the mutational resistome showed that all isolates had one major alteration in at least one of the genes analyzed. Loss of <italic>bla</italic><sub>PER-3</sub> gene restored susceptibility to CZA, ceftolozane/tazobactam and other β-lactamsin the <italic>in vitro</italic> evolved isolate. </p></sec><sec><title>Discussion</title><p>PER-3-producing ST309 <italic>P. aeruginosa</italic> is a successful multidrug-resistant clone with <italic>bla<sub>PER-3</sub></italic> gene implicated in resistance to CZA and other β-lactams.</p></sec>