{"title":"In vitro activity of cefiderocol against Pseudomonas aeruginosa isolated from adult patients with cystic fibrosis.","authors":"Saied Ali, Sinead McDermott","doi":"10.1099/acmi.0.001001.v3","DOIUrl":null,"url":null,"abstract":"<p><p><b>Background.</b> <i>Pseudomonas aeruginosa</i> is a key pathogen in cystic fibrosis (CF), driving pulmonary decline and exhibiting resistance through virulence factors and adaptive mutations. Cefiderocol (FDC) is a novel siderophore cephalosporin with activity against Gram-negative bacteria. We aimed to assess the <i>in vitro</i> efficacy of FDC against <i>P. aeruginosa</i> isolates in a CF population. <b>Methods.</b> The study was conducted in a tertiary hospital with a specialist adult CF service. All first isolates of significant respiratory pathogens among this cohort are cryopreserved at -80 °C. Antimicrobial susceptibility testing to FDC was performed as per European Committee on Antimicrobial Susceptibility Testing Disk-Diffusion (version 10) for all stored isolates of <i>P. aeruginosa</i> from 2017 to 2022 inclusive. <b>Results.</b> Eighty-five isolates from seventy-one patients were included. Resistance phenotypes comprised 19% (<i>n</i>=16) multidrug-resistant (MDR), 16% (<i>n</i>=14) extensively drug-resistant (XDR) and 24% (<i>n</i>=20) pandrug-resistant (PDR), with 24 % (<i>n</i>=20) exhibiting the mucoid phenotype. Overall, 85% of isolates were susceptible to FDC, with a mean inhibition zone of 25.2 mm. Antimicrobial activity was retained in 81% of MDR, 86% of XDR, 60% of PDR and 90% of mucoid isolates. Seventy-four per cent of meropenem-non-susceptible isolates remained susceptible to FDC, compared with lower susceptibility to ceftolozane-tazobactam (42%), tobramycin (36%) and ciprofloxacin (22%). <b>Conclusion.</b> FDC exhibited excellent <i>in vitro</i> activity against <i>P. aeruginosa</i> from adults with CF, including highly resistant and mucoid phenotypes. These findings highlight its potential as a salvage option in this high-risk population and provide the first Irish surveillance data to inform antimicrobial stewardship and future clinical use.</p>","PeriodicalId":94366,"journal":{"name":"Access microbiology","volume":"7 9","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12451307/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Access microbiology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1099/acmi.0.001001.v3","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/1/1 0:00:00","PubModel":"eCollection","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Background.Pseudomonas aeruginosa is a key pathogen in cystic fibrosis (CF), driving pulmonary decline and exhibiting resistance through virulence factors and adaptive mutations. Cefiderocol (FDC) is a novel siderophore cephalosporin with activity against Gram-negative bacteria. We aimed to assess the in vitro efficacy of FDC against P. aeruginosa isolates in a CF population. Methods. The study was conducted in a tertiary hospital with a specialist adult CF service. All first isolates of significant respiratory pathogens among this cohort are cryopreserved at -80 °C. Antimicrobial susceptibility testing to FDC was performed as per European Committee on Antimicrobial Susceptibility Testing Disk-Diffusion (version 10) for all stored isolates of P. aeruginosa from 2017 to 2022 inclusive. Results. Eighty-five isolates from seventy-one patients were included. Resistance phenotypes comprised 19% (n=16) multidrug-resistant (MDR), 16% (n=14) extensively drug-resistant (XDR) and 24% (n=20) pandrug-resistant (PDR), with 24 % (n=20) exhibiting the mucoid phenotype. Overall, 85% of isolates were susceptible to FDC, with a mean inhibition zone of 25.2 mm. Antimicrobial activity was retained in 81% of MDR, 86% of XDR, 60% of PDR and 90% of mucoid isolates. Seventy-four per cent of meropenem-non-susceptible isolates remained susceptible to FDC, compared with lower susceptibility to ceftolozane-tazobactam (42%), tobramycin (36%) and ciprofloxacin (22%). Conclusion. FDC exhibited excellent in vitro activity against P. aeruginosa from adults with CF, including highly resistant and mucoid phenotypes. These findings highlight its potential as a salvage option in this high-risk population and provide the first Irish surveillance data to inform antimicrobial stewardship and future clinical use.