{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T01:18:37Z","timestamp":1784855917044,"version":"3.55.0"},"reference-count":20,"publisher":"Oxford University Press (OUP)","issue":"5","license":[{"start":{"date-parts":[[2025,3,4]],"date-time":"2025-03-04T00:00:00Z","timestamp":1741046400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Korean government","award":["RS-2024-00357801"],"award-info":[{"award-number":["RS-2024-00357801"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,5,2]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>This study compared the efficacy of cefazolin in a mouse pneumonia model caused by a methicillin-susceptible Staphylococcus aureus (MSSA) strain with cefazolin inoculum effect (CIE) and its blaZ-eliminated derivative.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>An isogenic blaZ gene-eliminated strain was derived from type A blaZ-positive MSSA blood isolates exhibiting CIE: PNIDSA230 (parental strain, CIE+) and PNIDSA230c (blaZ-eliminated strain, CIE\u2212). Mice were inoculated with 2\u200a\u00d7\u200a10\u2076 to 2\u200a\u00d7\u200a10\u2077\u2005cfu of MSSA via endotracheal tubes and treated with intraperitoneal cefazolin or oxacillin 5\u2005h post-inoculation. Bacterial loads in the lungs (primary sites), liver, and kidneys (metastatic foci) were measured 24\u2005h later.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Cefazolin reduced bacterial densities in the lungs of CIE-positive MSSA-infected mice (n\u200a=\u200a11) compared with untreated controls (n\u200a=\u200a11) (mean log10\u2005cfu\/g\u200a\u00b1\u200aSD, 6.0\u200a\u00b1\u200a1.6 versus 9.4\u200a\u00b1\u200a2.7; P\u200a=\u200a0.006). However, the efficacy of cefazolin was significantly lower in CIE+ infections than in CIE\u2212 infections (mean log10\u2005cfu\/g\u200a\u00b1\u200aSD, 6.0\u200a\u00b1\u200a1.6 versus 4.4\u200a\u00b1\u200a0.8, P\u200a=\u200a0.0258). Cefazolin-treated CIE\u2212 MSSA-infected mice showed no metastatic infections, while 7 of the 11 CIE+ MSSA-infected mice developed liver or kidney infections despite cefazolin treatment. Oxacillin treatment significantly reduced bacterial densities of the lungs, liver, and kidney in CIE-positive (n\u200a=\u200a4) and CIE-negative (n\u200a=\u200a4) MSSA-infected mice, with no significant differences between CIE-positive and CIE-negative MSSA infections.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>CIE may diminish cefazolin\u2019s efficacy in severe MSSA infections and contribute to the development of metastatic infection foci. Oxacillin remains effective regardless of CIE status.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1093\/jac\/dkaf065","type":"journal-article","created":{"date-parts":[[2025,3,5]],"date-time":"2025-03-05T01:29:51Z","timestamp":1741138191000},"page":"1287-1290","source":"Crossref","is-referenced-by-count":6,"title":["<i>In vivo<\/i> evaluation of cefazolin inoculum effect in the treatment of experimental <i>Staphylococcus aureus<\/i> pneumonia with cefazolin"],"prefix":"10.1093","volume":"80","author":[{"given":"Soon Ok","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Internal Medicine, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital , Busan ,","place":["Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7652-7093","authenticated-orcid":false,"given":"Shinwon","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital , Busan ,","place":["Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sohee","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital , Busan ,","place":["Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeong Eun","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital , Busan ,","place":["Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sun Hee","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital , Busan ,","place":["Republic of Korea"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2025,3,4]]},"reference":[{"key":"2025050205521647700_dkaf065-B1","doi-asserted-by":"publisher","first-page":"507","DOI":"10.1086\/431979","article-title":"Staphylococcus aureus native valve infective endocarditis: report of 566 episodes from the International Collaboration on Endocarditis Merged Database","volume":"41","author":"Miro","year":"2005","journal-title":"Clin Infect 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