{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T11:57:46Z","timestamp":1792756666323,"version":"4.5.0"},"reference-count":21,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2024,12,17]],"date-time":"2024-12-17T00:00:00Z","timestamp":1734393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Pfizer"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background\/Objectives: Metallo-\u03b2-lactamases (MBLs) in Enterobacterales and other Gram-negative organisms pose significant public health threats due to their association with multidrug resistance (MDR). Although aztreonam (AZT) can target MBL-producing organisms, its efficacy is compromised in organisms expressing additional \u03b2-lactamases that inactivate it. Combining AZT with the \u03b2-lactamase inhibitor avibactam (AVI) may restore its activity against MBL-producing isolates. Methods: AZT-AVI, along with other clinically relevant antimicrobials, was tested against thirteen MBL-producing clinical isolates of Enterobacterales (nine Klebsiella pneumoniae, three Enterobacter cloacae, and one Providencia stuartii) using whole-genome sequencing (WGS) for genetic characterization. Results: AZT-AVI demonstrated full susceptibility across all isolates, whereas aztreonam alone was ineffective. The newer \u03b2-lactam\/\u03b2-lactamase inhibitor combinations imipenem\/relebactam and meropenem\/vaborbactam were inactive in 100% and 92.3% of isolates, respectively. WGS-based analysis revealed multiple resistance mechanisms consistent with MDR phenotypes, including high-risk K. pneumoniae clones (ST147 and ST11). Conclusions: AZT-AVI is effective against MDR MBL-producing Enterobacterales, highlighting its therapeutic potential for challenging infections. While WGS does not replace phenotypic testing, it provides valuable insights for antimicrobial stewardship and the monitoring of resistance gene dissemination.<\/jats:p>","DOI":"10.3390\/antibiotics13121221","type":"journal-article","created":{"date-parts":[[2024,12,17]],"date-time":"2024-12-17T05:26:02Z","timestamp":1734413162000},"page":"1221","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Characterization of Metallo \u03b2-Lactamase Producing Enterobacterales Isolates with Susceptibility to the Aztreonam\/Avibactam Combination"],"prefix":"10.3390","volume":"13","author":[{"given":"Brunella","family":"Posteraro","sequence":"first","affiliation":[{"name":"Unit\u00e0 Operativa \u201cMedicina di Precisione in Microbiologia Clinica\u201d, Direzione Scientifica, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy"},{"name":"Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Universit\u00e0 Cattolica del Sacro Cuore, 00168 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4744-9820","authenticated-orcid":false,"given":"Flavio","family":"De Maio","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze di Laboratorio ed Ematologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Teresa","family":"Spanu","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze di Laboratorio ed Ematologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8038-3026","authenticated-orcid":false,"given":"Maria Alejandra","family":"Vidal Pereira","sequence":"additional","affiliation":[{"name":"Medical Affairs, Pfizer Italia, 00188 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Francesca Romana","family":"Fasano","sequence":"additional","affiliation":[{"name":"Medical Affairs, Pfizer Italia, 00188 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9780-7059","authenticated-orcid":false,"given":"Maurizio","family":"Sanguinetti","sequence":"additional","affiliation":[{"name":"Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Universit\u00e0 Cattolica del Sacro Cuore, 00168 Rome, Italy"},{"name":"Dipartimento di Scienze di Laboratorio ed Ematologiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, 00168 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,12,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e00397-20","DOI":"10.1128\/AAC.00397-20","article-title":"Metallo-\u03b2-lactamases: Structure, function, epidemiology, treatment options, and the development pipeline","volume":"64","author":"Boyd","year":"2020","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e00047-19","DOI":"10.1128\/CMR.00047-19","article-title":"Epidemiology of \u03b2-lactamase-producing pathogens","volume":"33","author":"Bush","year":"2020","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"125","DOI":"10.2147\/IDR.S246174","article-title":"Therapeutic options for metallo-\u03b2-lactamase-producing Enterobacterales","volume":"14","author":"Tan","year":"2021","journal-title":"Infect. 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