{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T20:47:45Z","timestamp":1780519665057,"version":"3.54.1"},"reference-count":0,"publisher":"Knowledge E DMCC","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJM"],"abstract":"<jats:p>Background and Objectives: Imipenem\/relebactam (IMP\/R) is a newly FDA approved \u03b2-lactam\/\u03b2-lactamase inhibitor combination. Relebactam ability to restore IMP activity could differ according to the cause of imipenem non-susceptibility. Therefore, we investigated the in-vitro activity of IMP\/R against Klebsiella pneumoniae with different mechanisms of imi- penem non-susceptibility.\r\nMaterials and Methods: Imipenem-nonsusceptible (IMP-NS) K. pneumoniae isolates were collected and characterized for \u03b2-lactamase encoding genes by multiplex PCR. For IMP-NS carbapenemase-negative isolates, study of Ompk35 &amp; Ompk36 gene expression was performed by reverse transcription-PCR while efflux pump activity was studied by minimum inhibitory concentration (MIC) reduction assay using efflux pump inhibitor. Susceptibility testing of K. pneumoniae to IMP and IMP\/R were achieved by broth microdilution (BMD) method.\r\nResults: During the study period, 140 isolates of IMP-NS K. pneumoniae were collected. BMD method showed that relebac- tam restored IMP susceptibility in 100%, 60% and 49% of isolates that only harbor AmpC, extended spectrum beta lactamase (ESBL) and carbapenemases, respectively. IMP\/R was most potent against all bla KPC and 50% of bla _producing isolates. No demonstrable activity of IMP\/R against K. pneumoniae harboring metallo-\u03b2-lactamases (MBLs). Out of 18 isolates with IMP non-suceptibility due to porins loss with overproduction of ESBL and\/or AmpC, 14 (77.7%) isolates were IMP\/R sus- ceptible. IMP\/R showed no activity against isolates with only efflux pump hyperactivity.\r\nConclusion: Relebactam could restore IPM activity in KPC or AmpC-producing IMP\/NS K. pneumoniae but with no ac- tivity against MBL- producing isolates. Relebactam activity against isolates harbouring-bla OXA-48 or with altered Ompk35 &amp; Ompk36 gene expression and efflux pump hyperactivity need further studies. Therefore, using IMP\/R antibiotic in the treat- ment of infections caused by IMP\/NS K. pneumoniae should be based on its molecular profile of IMP resistance to optimize the utility of IMP\/R.<\/jats:p>","DOI":"10.18502\/ijm.v13i6.8080","type":"journal-article","created":{"date-parts":[[2021,12,25]],"date-time":"2021-12-25T06:41:25Z","timestamp":1640414485000},"source":"Crossref","is-referenced-by-count":4,"title":["Activity of imipenem\/relebactam on Klebsiella pneumoniae with different mechanisms of imipenem non-susceptibility"],"prefix":"10.18502","author":[{"given":"Mervat El-Sayed","family":"Mashaly","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ghada El-Saeed","family":"Mashaly","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"7770","published-online":{"date-parts":[[2021,12,22]]},"container-title":["Iranian Journal of Microbiology"],"original-title":[],"link":[{"URL":"https:\/\/publish.kne-publishing.com\/index.php\/IJM\/article\/download\/8080\/7756","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/publish.kne-publishing.com\/index.php\/IJM\/article\/download\/8080\/7756","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,12,17]],"date-time":"2024-12-17T16:45:26Z","timestamp":1734453926000},"score":1,"resource":{"primary":{"URL":"https:\/\/publish.kne-publishing.com\/index.php\/IJM\/article\/view\/8080"},"secondary":[{"URL":"https:\/\/ijm.tums.ac.ir\/index.php\/ijm\/article\/view\/3234","label":"UNIVERSITY"},{"URL":"https:\/\/publish.kne-publishing.com\/index.php\/IJM\/article\/view\/8080","label":"PUBLISHER"}]},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,22]]},"references-count":0,"URL":"https:\/\/doi.org\/10.18502\/ijm.v13i6.8080","relation":{},"ISSN":["2008-4447","2008-3289"],"issn-type":[{"value":"2008-4447","type":"electronic"},{"value":"2008-3289","type":"print"}],"subject":[],"published":{"date-parts":[[2021,12,22]]}}}