{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T19:16:36Z","timestamp":1791486996211,"version":"4.3.4"},"reference-count":8,"publisher":"Oxford University Press (OUP)","issue":"5","license":[{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"vor","delay-in-days":37,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009947","name":"MSD (UK) Limited, London, UK","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100009947","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>A subset of clinical Pseudomonas aeruginosa isolates from the INVICTUS I study was selected to compare antimicrobial susceptibility performance for disc diffusion and broth microdilution of ceftolozane\/tazobactam and five comparator antipseudomonal agents.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Overall, 159 non\u2013cystic fibrosis isolates were chosen from INVICTUS I that had the smallest zone diameters from disc testing to ceftolozane\/tazobactam, including isolates that were close to the breakpoints. The isolates were tested across 14 centres in the UK. Susceptibility results were interpreted using EUCAST 2026 criteria.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Discrepancy analysis showed combined error rates (very major and major errors) highest for ceftolozane\/tazobactam, ceftazidime and piperacillin\/tazobactam (15.7%, 14.5% and 12.6%, respectively); when adjusted to remove isolates close to the breakpoint for ceftolozane\/tazobactam and piperacillin\/tazobactam there were still remarkably high error rates (10.6% and 7.2%, respectively). Essential agreement and bias analysis were not performed as MICs were being compared with zone diameters.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>Our findings highlight substantial challenges in performing and interpreting susceptibility testing for these two important antipseudomonal \u03b2-lactam\/\u03b2-lactamase inhibitors, which are commonly employed as either first-line empirical therapy (piperacillin\/tazobactam) or for serious and MDR infection (ceftolozane\/tazobactam). A review of disc testing for these agents may be warranted, and diagnostic laboratories may wish to review the technical limitations and put in place mitigating measures.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/jacamr\/dlag212","type":"journal-article","created":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T12:03:06Z","timestamp":1789473786000},"source":"Crossref","is-referenced-by-count":0,"title":["INVICTUS II: comparison of disc diffusion and broth microdilution methods for susceptibility testing of ceftolozane\/tazobactam and five comparator agents against a subset of INVICTUS I\n                    <i>Pseudomonas aeruginosa<\/i>\n                    clinical isolates"],"prefix":"10.1093","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-6017-8865","authenticated-orcid":false,"given":"Kate","family":"Baldwin","sequence":"first","affiliation":[{"name":"Specialist Antimicrobial Chemotherapy Unit, Public Health Wales NHS , Cardiff ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adela","family":"Alvarez-Buylla","sequence":"additional","affiliation":[{"name":"Medical Affairs, MSD (UK) Limited , 120 Moorgate, London EC2M 6UR ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Allen","sequence":"additional","affiliation":[{"name":"Medical Affairs, MSD (UK) Limited , 120 Moorgate, London EC2M 6UR ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ricky","family":"Henry-Grant","sequence":"additional","affiliation":[{"name":"Medical Affairs, MSD (UK) Limited , 120 Moorgate, London EC2M 6UR ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Edita Custic","family":"Weguelin","sequence":"additional","affiliation":[{"name":"Medical Affairs, MSD (UK) Limited , 120 Moorgate, London EC2M 6UR ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2227-3355","authenticated-orcid":false,"given":"Mandy","family":"Wootton","sequence":"additional","affiliation":[{"name":"Specialist Antimicrobial Chemotherapy Unit, Public Health Wales NHS , Cardiff ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,10,8]]},"reference":[{"key":"2026100814211781000_dlag212-B1","doi-asserted-by":"publisher","first-page":"1089","DOI":"10.1093\/cid\/ciy215","article-title":"Changing rates of chronic Pseudomonas aeruginosa infections in cystic fibrosis: a population-based cohort study","volume":"67","author":"Crull","year":"2018","journal-title":"Clin Infect Dis"},{"key":"2026100814211781000_dlag212-B2","author":"European Centre for Disease Prevention and Control"},{"key":"2026100814211781000_dlag212-B3","doi-asserted-by":"publisher","DOI":"10.1093\/jacamr\/dlaa024","article-title":"Multicentre study of the in vitro activity of ceftolozane\/tazobactam and other commonly used antibiotics against Pseudomonas aeruginosa isolates from patients in the UK","volume":"2","author":"Alvarez-Buylla","year":"2020","journal-title":"JAC Antimicrob Resist"},{"key":"2026100814211781000_dlag212-B4","doi-asserted-by":"publisher","first-page":"2278","DOI":"10.1093\/jac\/dkx136","article-title":"Activity of ceftolozane\/tazobactam against surveillance and \u201cproblem\u201d Enterobacteriaceae, Pseudomonas aeruginosa and non-fermenters from the British Isles","volume":"72","author":"Livermore","year":"2017","journal-title":"J Antimicrob Chemother"},{"key":"2026100814211781000_dlag212-B5","doi-asserted-by":"publisher","first-page":"2249","DOI":"10.1128\/AAC.02151-13","article-title":"Impact of renal function on the pharmacokinetics and safety of ceftolozane\/tazobactam","volume":"58","author":"Wooley","year":"2014","journal-title":"Antimicrob Agents Chemother"},{"key":"2026100814211781000_dlag212-B6","author":"EUCAST"},{"key":"2026100814211781000_dlag212-B7","author":"International Organization for Standardization. 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