{"doi":"10.1093/jac/dkaf361","title":"Comparative evaluation of disc diffusion and broth microdilution methods for aztreonam/avibactam susceptibility testing in Enterobacterales","abstract":"BACKGROUND: Aztreonam/avibactam is a novel β-lactam/β-lactamase inhibitor (BL/BLI) combination active against carbapenem-resistant Enterobacterales (CRE), including MBL-producing isolates. In May 2024, EUCAST published Enterobacterales breakpoints for aztreonam/avibactam. This study aimed to assess the performance of commercially available disc diffusion (DD) against broth microdilution (BMD) using the latest EUCAST breakpoints. METHODS: We tested 278 CRE causing infections in 17 Greek ICUs between 2021 and 2023, using 30/20 μg aztreonam/avibactam discs and BMD according to EUCAST methodology and EUCAST version 15.0 breakpoints. RESULTS: Most isolates were identified as Klebsiella pneumoniae (97.8%), and 98.9% produced carbapenemases, including 46.4% KPC, 20.1% NDM, 5.4% VIM and 27% multiple carbapenemases. Using BMD, 94.2% of isolates were susceptible to aztreonam/avibactam. Conversely, using DD, 66.9% were susceptible, 33.1% resistant and 27% within the area of technical uncertainty (ATU). Most isolates in the ATU were KPC-producing (68%) or KPC and MBL-producing (29.3%). All isolates in the ATU (22-24 mm) tested susceptible by BMD (MIC ≤ 4 mg/L). One isolate exhibited resistance by DD (20 mm), but was susceptible by BMD. Categorical agreement (CA) was 72.7%, with 29% major errors (MEs) and 0% very major errors (VMEs). Using a breakpoint of 22 mm, CA, ME and VME were 99.6%, 0.4% and 0%, respectively. CONCLUSIONS: Aztreonam/avibactam showed potent in vitro activity against MBL- and KPC-producing Enterobacterales. Using the 2025 EUCAST breakpoint, all isolates in the ATU tested susceptible by BMD, leading to high MEs of the DD method. A 22 mm breakpoint would have corrected this discrepancy in our cohort.","journal":"Journal of Antimicrobial Chemotherapy","year":2025,"id":526994,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":3,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9479,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1403609,"name":"Deny Tsakri","orcid":null,"position":1,"is_corresponding":false},{"id":1403610,"name":"S. Vourli","orcid":null,"position":2,"is_corresponding":false},{"id":1403611,"name":"Himani Solanki","orcid":null,"position":3,"is_corresponding":false},{"id":1403612,"name":"Evelyn Murrell","orcid":null,"position":4,"is_corresponding":false},{"id":1403613,"name":"Eftychia Kiousi","orcid":null,"position":5,"is_corresponding":false},{"id":1403614,"name":"Zacharias Tsakris","orcid":null,"position":6,"is_corresponding":false},{"id":1403615,"name":"Gabriella Kuczmar","orcid":null,"position":7,"is_corresponding":false},{"id":1403616,"name":"Nikoletta Smyrni","orcid":null,"position":8,"is_corresponding":false},{"id":1403119,"name":"Ioannis Skiadas","orcid":"0000-0002-6458-678X","position":9,"is_corresponding":false},{"id":1403617,"name":"Vassilios Grammelis","orcid":null,"position":10,"is_corresponding":false},{"id":658365,"name":"James Hatcher","orcid":"0000-0003-2417-346X","position":11,"is_corresponding":false},{"id":1403618,"name":"Damianos Menegas","orcid":null,"position":12,"is_corresponding":false},{"id":60531,"name":"Athanasios Tsakris","orcid":"0000-0003-0656-4715","position":13,"is_corresponding":false},{"id":1403619,"name":"Georgia Vrioni","orcid":null,"position":14,"is_corresponding":false},{"id":231908,"name":"Louis Grandjean","orcid":"0000-0002-1457-8327","position":15,"is_corresponding":false},{"id":1262998,"name":"Ioannis Baltas","orcid":"0000-0002-8008-4835","position":0,"is_corresponding":true}],"reference_count":10,"raw_metadata":null,"created_at":"2026-07-19T02:50:34.851930Z","pmid":"41001706","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}