{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T16:48:51Z","timestamp":1787503731677,"version":"build-2736575974"},"reference-count":21,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,11,17]],"date-time":"2025-11-17T00:00:00Z","timestamp":1763337600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Fundaci\u00f3n para la Investigaci\u00f3n Biosanitaria de Andaluc\u00eda Oriental","award":["G18374199"],"award-info":[{"award-number":["G18374199"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background: Cefiderocol, a novel siderophore cephalosporin, has shown promising activity against multidrug-resistant (MDR) Gram-negative pathogens, including metallo-\u03b2-lactamase (MBL) producers. However, emerging reports suggest rapid resistance development under selective pressure, particularly in epidemic Pseudomonas aeruginosa lineages. Case presentation: We describe a 50-year-old man with a history of aortic dissection who developed ventilator-associated pneumonia due to P. aeruginosa ST175 carrying an IMP-type carbapenemase. Initial treatment with ceftazidime\/avibactam plus aztreonam was followed by cefiderocol monotherapy. Although the patient showed early improvement, clinical relapse occurred within days, with subsequent isolation of cefiderocol-resistant P. aeruginosa. Whole-genome sequencing revealed high-impact mutations in iron acquisition systems (including fptA and pvdE) and multiple resistance determinants (oprD, efflux pump regulators, ampD\/ampR), disrupting siderophore-mediated uptake and favoring multidrug resistance. Despite rescue therapy with ceftazidime\/avibactam plus aztreonam and adjunctive agents, the patient ultimately died from septic shock and multiorgan failure. Discussion: This case highlights the ability of high-risk P. aeruginosa clones to rapidly adapt to cefiderocol, driven by combined alterations in iron metabolism and classical resistance pathways. The development of resistance within less than one week of exposure underscores the risk of using cefiderocol as monotherapy in infections caused by epidemic MDR clones. Conclusions: Cefiderocol resistance can emerge rapidly in vivo during treatment of infections caused by P. aeruginosa ST175. Continuous surveillance, molecular characterization of resistance mechanisms, and cautious use of cefiderocol\u2014preferably in combination regimens\u2014are warranted to preserve its clinical utility.<\/jats:p>","DOI":"10.3390\/antibiotics14111162","type":"journal-article","created":{"date-parts":[[2025,11,17]],"date-time":"2025-11-17T10:24:58Z","timestamp":1763375098000},"page":"1162","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Cefiderocol Resistance in Pseudomonas aeruginosa ST175: A Case Report with Genomic Analysis"],"prefix":"10.3390","volume":"14","author":[{"given":"Rosario Fern\u00e1ndez","family":"Fern\u00e1ndez","sequence":"first","affiliation":[{"name":"Intensive Medicine, Hospital San Cecilio, 18016 Granada, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alberto Badillo","family":"Carrasco","sequence":"additional","affiliation":[{"name":"Microbiology Unit, Hospital San Cecilio, 18016 Granada, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3420-3290","authenticated-orcid":false,"given":"Natalia Chueca","family":"Porcuna","sequence":"additional","affiliation":[{"name":"Microbiology Unit, Hospital San Cecilio, 18016 Granada, Spain"},{"name":"Institute of Biosanitary Research (ibs.GRANADA), Hospital San Cecilio, 18016 Granada, Spain"},{"name":"Spanish Consortium for Research on Infectious Diseases (CIBERINFEC), 28029 Madrid, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antonio Mart\u00ednez","family":"Cabezas","sequence":"additional","affiliation":[{"name":"Intensive Medicine, Hospital San Cecilio, 18016 Granada, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5005-1154","authenticated-orcid":false,"given":"Manuel Colmenero","family":"Ruiz","sequence":"additional","affiliation":[{"name":"Intensive Care Medicine Service, Hospital San Cecilio, 18016 Granada, Spain"},{"name":"Department of Medicine, Facultad Medicina, Universidad Granada, 18012 Granada, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/S0168-6445(03)00055-X","article-title":"Bacterial iron homeostasis","volume":"27","author":"Andrews","year":"2003","journal-title":"FEMS Microbiol. 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