{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T02:19:35Z","timestamp":1782267575123,"version":"3.54.5"},"reference-count":23,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T00:00:00Z","timestamp":1760054400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant therapeutic challenge, particularly when multiple resistance mechanisms, such as metallo-\u03b2-lactamases (MBLs) and Klebsiella pneumoniae carbapenemase (KPC), coexist. Case description: We describe a case of a 51-year-old male with a post-sternotomy surgical site infection and concurrent bacteremia caused by a CRKP. Sternal swab and mediastinal liquid culture results highlighted CRKP harboring blaNDM and blaKPC genes, while the blood isolate showed blaCTX and blaKPC, indicating phenotypic resistance to ceftazidime-avibactam. All the strains exhibited phenotypic susceptibility to meropenem-vaborbactam (MEV), despite having a high minimum inhibitory concentration. Following clinical failure of MEV-based therapy, combination treatment with aztreonam (ATM) and imipenem\/cilastatin\/relebactam (IMI\/REL), plus gentamicin, was initiated. Therapy was well tolerated and resulted in microbiological eradication and full clinical recovery. The patient completed 49 days of ATM and IMI\/REL without relapse over a 3-month follow-up period. This is, to the best of our knowledge, the first reported case of IMI\/REL being used in combination with ATM.<\/jats:p>","DOI":"10.3390\/antibiotics14101007","type":"journal-article","created":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:50:16Z","timestamp":1760107816000},"page":"1007","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Imipenem\/Relebactam Plus Aztreonam: First Reported Use in MDR Klebsiella pneumoniae Sternal Infection Complicated by Bacteremia"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1871-4285","authenticated-orcid":false,"given":"Luca","family":"Pipit\u00f2","sequence":"first","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Infectious and Tropical Disease Unit and Sicilian Regional Reference Center for the Fight Against AIDS, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"},{"name":"Antimicrobial Stewardship Team, AOU Policlinico \u201cP. Giaccone\u201d, 90127 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raffaella","family":"Rubino","sequence":"additional","affiliation":[{"name":"Infectious and Tropical Disease Unit and Sicilian Regional Reference Center for the Fight Against AIDS, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"},{"name":"Antimicrobial Stewardship Team, AOU Policlinico \u201cP. Giaccone\u201d, 90127 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rita","family":"Immordino","sequence":"additional","affiliation":[{"name":"Microbiology and Virology Unit, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleonora","family":"Bono","sequence":"additional","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Infectious and Tropical Disease Unit and Sicilian Regional Reference Center for the Fight Against AIDS, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Teresa","family":"Fasciana","sequence":"additional","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Microbiology and Virology Unit, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6250-9203","authenticated-orcid":false,"given":"Celestino","family":"Bonura","sequence":"additional","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Microbiology and Virology Unit, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7874-6289","authenticated-orcid":false,"given":"Giovanni Maurizio","family":"Giammanco","sequence":"additional","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Microbiology and Virology Unit, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vincenzo","family":"Argano","sequence":"additional","affiliation":[{"name":"Unit of Cardiac Surgery, University of Palermo, 90127 Palermo, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1992-1796","authenticated-orcid":false,"given":"Antonio","family":"Cascio","sequence":"additional","affiliation":[{"name":"Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties \u201cG D\u2019Alessandro\u201d, University of Palermo, 90133 Palermo, Italy"},{"name":"Infectious and Tropical Disease Unit and Sicilian Regional Reference Center for the Fight Against AIDS, AOU Policlinico \u201cP. Giaccone\u201d, 90133 Palermo, Italy"},{"name":"Antimicrobial Stewardship Team, AOU Policlinico \u201cP. 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