{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,9]],"date-time":"2026-10-09T07:44:40Z","timestamp":1791531880712,"version":"4.3.4"},"reference-count":38,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2021,11,3]],"date-time":"2021-11-03T00:00:00Z","timestamp":1635897600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.mdpi.com"],"crossmark-restriction":true},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Metallo-\u03b2-lactamases (MBLs) are among the most challenging bacterial enzymes to overcome. Aztreonam (ATM) is the only \u03b2-lactam not hydrolyzed by MBLs but is often inactivated by co-produced extended-spectrum \u03b2-lactamases (ESBL). We assessed the activity of the combination of ATM with old and new \u03b2-lactamases inhibitors (BLIs) against MBL and ESBL co-producing Gram-negative clinical isolates. Six Enterobacterales and three non-fermenting bacilli co-producing MBL and ESBL determinants were selected as difficult-to-treat pathogens. ESBLs and MBLs genes were characterized by PCR and sequencing. The activity of ATM in combination with seven different BLIs (clavulanate, sulbactam, tazobactam, vaborbactam, avibactam, relebactam, zidebactam) was assessed by microdilution assay and time\u2013kill curve. ATM plus avibactam was the most effective combination, able to restore ATM susceptibility in four out of nine tested isolates, reaching in some cases a 128-fold reduction of the MIC of ATM. In addition, relebactam and zidebactam showed to be effective, but with lesser reduction of the MIC of ATM. E. meningoseptica and C. indologenes were not inhibited by any ATM\u2013BLI combination. ATM\u2013BLI combinations demonstrated to be promising against MBL and ESBL co-producers, hence providing multiple options for treatment of related infections. However, no effective combination was found for some non-fermentative bacilli, suggesting the presence of additional resistance mechanisms that complicate the choice of an active therapy.<\/jats:p>","DOI":"10.3390\/antibiotics10111341","type":"journal-article","created":{"date-parts":[[2021,11,3]],"date-time":"2021-11-03T17:59:38Z","timestamp":1635962378000},"page":"1341","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":25,"title":["Antimicrobial Activity of Aztreonam in Combination with Old and New \u03b2-Lactamase Inhibitors against MBL and ESBL Co-Producing Gram-Negative Clinical Isolates: Possible Options for the Treatment of Complicated Infections"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0772-0214","authenticated-orcid":false,"given":"Gianluca","family":"Morroni","sequence":"first","affiliation":[{"name":"Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, 60126 Ancona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raffaela","family":"Bressan","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, University of Trieste, 34127 Trieste, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simona","family":"Fioriti","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, 60126 Ancona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gloria","family":"D\u2019Achille","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, 60126 Ancona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8225-7843","authenticated-orcid":false,"given":"Marina","family":"Mingoia","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, 60126 Ancona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oscar","family":"Cirioni","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences and Public Health, Polytechnic University of Marche, 60126 Ancona, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6121-7009","authenticated-orcid":false,"given":"Stefano","family":"Di Bella","sequence":"additional","affiliation":[{"name":"Clinical Department of Medical, Surgical and Health Sciences, University of Trieste, 34129 Trieste, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aurora","family":"Piazza","sequence":"additional","affiliation":[{"name":"Unit of Microbiology and Clinical Microbiology, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8298-4792","authenticated-orcid":false,"given":"Francesco","family":"Comandatore","sequence":"additional","affiliation":[{"name":"Department of Romeo and Enrica Invernizzi Pediatric Research Center, Department of Biomedical and Clinical Sciences L. Sacco, University of Milan, 20157 Milan, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2182-7325","authenticated-orcid":false,"given":"Carola","family":"Mauri","sequence":"additional","affiliation":[{"name":"Clinical Microbiology and Virology Unit, A. Manzoni Hospital, 23900 Lecco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roberta","family":"Migliavacca","sequence":"additional","affiliation":[{"name":"Unit of Microbiology and Clinical Microbiology, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, 27100 Pavia, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8275-8389","authenticated-orcid":false,"given":"Francesco","family":"Luzzaro","sequence":"additional","affiliation":[{"name":"Clinical Microbiology and Virology Unit, A. Manzoni Hospital, 23900 Lecco, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2000-5322","authenticated-orcid":false,"given":"Luigi","family":"Principe","sequence":"additional","affiliation":[{"name":"Clinical Pathology and Microbiology Unit, S. Giovanni di Dio Hospital, 88900 Crotone, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5739-6761","authenticated-orcid":false,"given":"Cristina","family":"Lagatolla","sequence":"additional","affiliation":[{"name":"Department of Life Sciences, University of Trieste, 34127 Trieste, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7957","DOI":"10.1021\/acs.chemrev.1c00138","article-title":"Metallo-\u03b2-Lactamases in the Age of Multidrug Resistance: From Structure and Mechanism to Evolution, Dissemination, and Inhibitor Design","volume":"121","author":"Bahr","year":"2021","journal-title":"Chem. Rev."},{"key":"ref_2","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_3","doi-asserted-by":"crossref","first-page":"3472","DOI":"10.1016\/j.jmb.2019.04.002","article-title":"\u03b2-Lactamases and \u03b2-Lactamase Inhibitors in the 21st Century","volume":"431","author":"Tooke","year":"2019","journal-title":"J. Mol. Biol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"ofaa011","DOI":"10.1093\/ofid\/ofaa011","article-title":"Clinical Features and Outcomes of Bloodstream Infections Caused by New Delhi Metallo-\u03b2-Lactamase-Producing Enterobacterales During a Regional Outbreak","volume":"7","author":"Falcone","year":"2020","journal-title":"Open Forum Infect. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2871","DOI":"10.3389\/fmicb.2018.02871","article-title":"Heterogeneous Colistin-Resistance Phenotypes Coexisting in Stenotrophomonas Maltophilia Isolates Influence Colistin Susceptibility Testing","volume":"9","author":"Yero","year":"2018","journal-title":"Front. Microbiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"816","DOI":"10.1089\/mdr.2017.0206","article-title":"Clinical Strains of Chryseobacterium and Elizabethkingia spp. Isolated from Pediatric Patients in a University Hospital: Performance of MALDI-TOF MS-Based Identification, Antimicrobial Susceptibilities, and Baseline Patient Characteristics","volume":"24","author":"Mirza","year":"2018","journal-title":"Microb. Drug Resist."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Mauri, C., Maraolo, A.E., Di Bella, S., Luzzaro, F., and Principe, L. (2021). The Revival of Aztreonam in Combination with Avibactam against Metallo-\u03b2-Lactamase-Producing Gram-Negatives: A Systematic Review of In Vitro Studies and Clinical Cases. Antibiotics, 10.","DOI":"10.3390\/antibiotics10081012"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Carcione, D., Siracusa, C., Sulejmani, A., Leoni, V., and Intra, J. (2021). Old and New Beta-Lactamase Inhibitors: Molecular Structure, Mechanism of Action, and Clinical Use. Antibiotics, 10.","DOI":"10.3390\/antibiotics10080995"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e00414-18","DOI":"10.1128\/AAC.00414-18","article-title":"Aztreonam-Avibactam Combination Restores Susceptibility of Aztreonam in Dual-Carbapenemase-Producing Enterobacteriaceae","volume":"62","author":"Chew","year":"2018","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"659","DOI":"10.1093\/jac\/dkaa504","article-title":"Aztreonam\/Avibactam Activity against Clinical Isolates of Enterobacterales Collected in Europe, Asia and Latin America in 2019","volume":"76","author":"Sader","year":"2021","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"674","DOI":"10.1093\/ajhp\/zxab012","article-title":"Imipenem\/Cilastatin\/Relebactam: A New Carbapenem \u03b2-Lactamase Inhibitor Combination","volume":"78","author":"Mansour","year":"2021","journal-title":"Am. J. Health-Syst. Pharm."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e00115-20","DOI":"10.1128\/CMR.00115-20","article-title":"New \u03b2-Lactam-\u03b2-Lactamase Inhibitor Combinations","volume":"34","author":"Yahav","year":"2020","journal-title":"Clin. Microbiol. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1696","DOI":"10.1093\/jac\/dkx050","article-title":"WCK 5222 (Cefepime\/Zidebactam) Antimicrobial Activity Tested against Gram-Negative Organisms Producing Clinically Relevant \u03b2-Lactamases","volume":"72","author":"Sader","year":"2017","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Thomson, K.S., AbdelGhani, S., Snyder, J.W., and Thomson, G.K. (2019). Activity of Cefepime-Zidebactam against Multidrug-Resistant (MDR) Gram-Negative Pathogens. Antibiotics, 8.","DOI":"10.3390\/antibiotics8010032"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1511","DOI":"10.1093\/jac\/dkab067","article-title":"Activity of Cefepime\/Zidebactam (WCK 5222) against \u201cproblem\u201d Antibiotic-Resistant Gram-Negative Bacteria Sent to a National Reference Laboratory","volume":"76","author":"Mushtaq","year":"2021","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1035","DOI":"10.2217\/fmb-2019-0069","article-title":"Increase and Diversity of Carbapenemase-Producing Escherichia coli Isolates, Italy","volume":"14","author":"Simoni","year":"2019","journal-title":"Future Microbiol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1186\/s13756-018-0326-0","article-title":"Colonization of Long-Term Care Facility Residents in Three Italian Provinces by Multidrug-Resistant Bacteria","volume":"7","author":"Nucleo","year":"2018","journal-title":"Antimicrob. Resist. Infect. Control"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"221","DOI":"10.2217\/fmb-2020-0204","article-title":"Synergistic Effect of Antimicrobial Peptide LL-37 and Colistin Combination against Multidrug-Resistant Escherichia coli Isolates","volume":"16","author":"Morroni","year":"2021","journal-title":"Future Microbiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.jgar.2016.10.004","article-title":"First Report of NDM-1-Producing Klebsiella pneumoniae Imported from Africa to Italy: Evidence of the Need for Continuous Surveillance","volume":"8","author":"Principe","year":"2017","journal-title":"J. Glob. Antimicrob. Resist."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1133","DOI":"10.1089\/mdr.2020.0037","article-title":"Zinc Chelators as Carbapenem Adjuvants for Metallo-\u03b2-Lactamase-Producing Bacteria: In Vitro and In Vivo Evaluation","volume":"26","author":"Principe","year":"2020","journal-title":"Microb. Drug Resist."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Mojica, M.F., Rossi, M.-A., Vila, A.J., and Bonomo, R.A. (2021). The Urgent Need for Metallo-\u03b2-Lactamase Inhibitors: An Unattended Global Threat. Lancet Infect. Dis.","DOI":"10.1016\/S1473-3099(20)30868-9"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e00010-19","DOI":"10.1128\/AAC.00010-19","article-title":"Aztreonam plus Clavulanate, Tazobactam, or Avibactam for Treatment of Infections Caused by Metallo-\u03b2-Lactamase-Producing Gram-Negative Bacteria","volume":"63","author":"Emeraud","year":"2019","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1292","DOI":"10.1099\/jmm.0.001052","article-title":"Synergistic in Vitro Activity between Aztreonam and Amoxicillin-Clavulanate against Enterobacteriaceae-Producing Class B and\/or Class D Carbapenemases with or without Extended-Spectrum \u03b2-Lactamases","volume":"68","author":"Ract","year":"2019","journal-title":"J. Med. Microbiol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e00174-18","DOI":"10.1128\/AAC.00174-18","article-title":"Relebactam Is a Potent Inhibitor of the KPC-2 \u03b2-Lactamase and Restores Imipenem Susceptibility in KPC-Producing Enterobacteriaceae","volume":"62","author":"Barnes","year":"2018","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1755","DOI":"10.1007\/s10096-021-04197-3","article-title":"Ceftazidime-Avibactam, Meropenen-Vaborbactam, and Imipenem-Relebactam in Combination with Aztreonam against Multidrug-Resistant, Metallo-\u03b2-Lactamase-Producing Klebsiella pneumoniae","volume":"40","author":"Maraki","year":"2021","journal-title":"Eur. J. Clin. Microbiol. Infect. Dis. Off. Publ. Eur. Soc. Clin. Microbiol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e00297-20","DOI":"10.1128\/AAC.00297-20","article-title":"Activity of Aztreonam in Combination with Avibactam, Clavulanate, Relebactam, and Vaborbactam against Multidrug-Resistant Stenotrophomonas maltophilia","volume":"64","author":"Biagi","year":"2020","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1914","DOI":"10.1128\/AAC.40.8.1914","article-title":"Comparison of Three Different in Vitro Methods of Detecting Synergy: Time\u2013Kill, Checkerboard, and E Test","volume":"40","author":"White","year":"1996","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Lin, J.-N., Lai, C.-H., Yang, C.-H., and Huang, Y.-H. (2019). Elizabethkingia Infections in Humans: From Genomics to Clinics. Microorganisms, 7.","DOI":"10.3390\/microorganisms7090295"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Jean, S.-S., Chang, Y.-C., Lin, W.-C., Lee, W.-S., Hsueh, P.-R., and Hsu, C.-W. (2020). Epidemiology, Treatment, and Prevention of Nosocomial Bacterial Pneumonia. J. Clin. Med., 9.","DOI":"10.3390\/jcm9010275"},{"key":"ref_30","unstructured":"The European Committee on Antimicrobial Susceptibility Testing (2020, November 01). Breakpoint Tables for Interpretation of MICs and Zone Diameters. Available online: https:\/\/www.eucast.org\/fileadmin\/src\/media\/PDFs\/EUCAST_files\/Breakpoint_tables\/v_10.0_Breakpoint_Tables.pdf."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1016\/j.ijantimicag.2016.05.006","article-title":"Evaluation of a DNA Microarray for Rapid Detection of the Most Prevalent Extended-Spectrum \u03b2-Lactamases, Plasmid-Mediated Cephalosporinases and Carbapenemases in Enterobacteriaceae, Pseudomonas and Acinetobacter","volume":"48","author":"Bogaerts","year":"2016","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2114","DOI":"10.1093\/bioinformatics\/btu170","article-title":"Trimmomatic: A Flexible Trimmer for Illumina Sequence Data","volume":"30","author":"Bolger","year":"2014","journal-title":"Bioinformatics"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"714","DOI":"10.1089\/cmb.2013.0084","article-title":"Assembling Single-Cell Genomes and Mini-Metagenomes from Chimeric MDA Products","volume":"20","author":"Nurk","year":"2013","journal-title":"J. Comput. Biol. J. Comput. Mol. Cell Biol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2640","DOI":"10.1093\/jac\/dks261","article-title":"Identification of Acquired Antimicrobial Resistance Genes","volume":"67","author":"Zankari","year":"2012","journal-title":"J. Antimicrob. Chemother."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"90","DOI":"10.1186\/s13073-014-0090-6","article-title":"SRST2: Rapid Genomic Surveillance for Public Health and Hospital Microbiology Labs","volume":"6","author":"Inouye","year":"2014","journal-title":"Genome Med."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1128\/AAC.01310-13","article-title":"ARG-ANNOT, a New Bioinformatic Tool to Discover Antibiotic Resistance Genes in Bacterial Genomes","volume":"58","author":"Gupta","year":"2014","journal-title":"Antimicrob. Agents Chemother."},{"key":"ref_37","unstructured":"EUCAST (2021, June 01). EUCAST Reading Guide for Broth Microdilution V.3 2021. Available online: https:\/\/eucast.org\/ast_of_bacteria\/mic_determination\/."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"4124","DOI":"10.1128\/JCM.01121-14","article-title":"When Does 2 plus 2 Equal 5? A Review of Antimicrobial Synergy Testing","volume":"52","author":"Doern","year":"2014","journal-title":"J. Clin. Microbiol."}],"updated-by":[{"DOI":"10.3390\/antibiotics11040464","type":"correction","label":"Correction","source":"publisher","updated":{"date-parts":[[2021,11,3]],"date-time":"2021-11-03T00:00:00Z","timestamp":1635897600000}}],"container-title":["Antibiotics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6382\/10\/11\/1341\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,3]],"date-time":"2025-08-03T22:49:47Z","timestamp":1754261387000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6382\/10\/11\/1341"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,11,3]]},"references-count":38,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["antibiotics10111341"],"URL":"https:\/\/doi.org\/10.3390\/antibiotics10111341","relation":{"correction":[{"id-type":"doi","id":"10.3390\/antibiotics11040464","asserted-by":"object"}]},"ISSN":["2079-6382"],"issn-type":[{"value":"2079-6382","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,11,3]]}}}