{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,18]],"date-time":"2026-10-18T01:27:38Z","timestamp":1792286858967,"version":"4.4.0"},"reference-count":30,"publisher":"American Society for Microbiology","issue":"8","license":[{"start":{"date-parts":[[2009,8,1]],"date-time":"2009-08-01T00:00:00Z","timestamp":1249084800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Antimicrob Agents Chemother"],"published-print":{"date-parts":[[2009,8]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Methicillin (meticillin)-susceptible\n                    <jats:italic>Staphylococcus aureus<\/jats:italic>\n                    (MSSA) strains producing large amounts of type A \u03b2-lactamase (Bla) have been associated with cefazolin failures, but the frequency and impact of these strains have not been well studied. Here we examined 98 MSSA clinical isolates and found that 26% produced type A Bla, 15% type B, 46% type C, and none type D and that 13% lacked\n                    <jats:italic>blaZ<\/jats:italic>\n                    . The cefazolin MIC\n                    <jats:sub>90<\/jats:sub>\n                    was 2 \u03bcg\/ml for a standard inoculum and 32 \u03bcg\/ml for a high inoculum, with 19% of isolates displaying a pronounced inoculum effect (MICs of \u226516 \u03bcg\/ml with 10\n                    <jats:sup>7<\/jats:sup>\n                    CFU\/ml) (9 type A and 10 type C Bla producers). At the high inoculum, type A producers displayed higher cefazolin MICs than type B or C producers, while type B and C producers displayed higher cefamandole MICs. Among isolates from hemodialysis patients with MSSA bacteremia, three from the six patients who experienced cefazolin failure showed a cefazolin inoculum effect, while none from the six patients successfully treated with cefazolin showed an inoculum effect, suggesting an association between these strains and cefazolin failure (\n                    <jats:italic>P<\/jats:italic>\n                    = 0.09 by Fisher's exact test). In summary, 19% of MSSA clinical isolates showed a pronounced inoculum effect with cefazolin, a phenomenon that could explain the cases of cefazolin failure previously reported for hemodialysis patients with MSSA bacteremia. These results suggest that for serious MSSA infections, the presence of a significant inoculum effect with cefazolin could be associated with clinical failure in patients treated with this cephalosporin, particularly when it is used at low doses.\n                  <\/jats:p>","DOI":"10.1128\/aac.00317-09","type":"journal-article","created":{"date-parts":[[2009,6,1]],"date-time":"2009-06-01T20:55:25Z","timestamp":1243889725000},"page":"3437-3441","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":144,"title":["Inoculum Effect with Cefazolin among Clinical Isolates of Methicillin-Susceptible\n                    <i>Staphylococcus aureus<\/i>\n                    : Frequency and Possible Cause of Cefazolin Treatment Failure"],"prefix":"10.1128","volume":"53","author":[{"given":"Esteban C.","family":"Nannini","sequence":"first","affiliation":[{"name":"Division of Infectious Diseases, School of Medicine, Universidad Nacional de Rosario, Rosario, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martin E.","family":"Stryjewski","sequence":"additional","affiliation":[{"name":"Duke Clinical Research Institute, Durham, North Carolina"},{"name":"Department of Medicine and Division of Infectious Diseases, Centro de Educacio\u0301n Me\u0301dica e Investigaciones Cli\u0301nicas Norberto Quirno (CEMIC), Buenos Aires, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kavindra V.","family":"Singh","sequence":"additional","affiliation":[{"name":"Center for the Study of Emerging and Re-Emerging Pathogens, Division of Infectious Diseases, Department of Internal Medicine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Agathe","family":"Bourgogne","sequence":"additional","affiliation":[{"name":"Center for the Study of Emerging and Re-Emerging Pathogens, Division of Infectious Diseases, Department of Internal Medicine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tom H.","family":"Rude","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G. Ralph","family":"Corey","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"suffix":"Jr.","given":"Vance G.","family":"Fowler","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Barbara E.","family":"Murray","sequence":"additional","affiliation":[{"name":"Center for the Study of Emerging and Re-Emerging Pathogens, Division of Infectious Diseases, Department of Internal Medicine"},{"name":"Department of Microbiology and Molecular Genetics, The University of Texas Medical School, Houston, Texas"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1161\/01.CIR.0000153812.64956.EF"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1099\/00222615-23-2-133"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1001\/jama.1977.03270330059022"},{"key":"e_1_3_2_5_2","unstructured":"Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard 2008"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1086\/430833"},{"key":"e_1_3_2_7_2","first-page":"975","volume":"1","year":"2005","unstructured":"Fowler, V. G., M. W. Scheld, and A. Bayer. 2005. Endocarditis and intravascular infections, p. 975-1022. In G. L. Mandell, J. E. Bennett, and R. Dolin (ed.), Principles and practice of infectious diseases, 6th ed., vol. 1. Elsevier Churchill Livingstone, Philadelphia, PA.","journal-title":"Principles and practice of infectious diseases"},{"key":"e_1_3_2_8_2","doi-asserted-by":"crossref","first-page":"S415","DOI":"10.1093\/infdis\/128.Supplement_2.S415","volume":"128","year":"1973","unstructured":"Gold, J. A., J. J. McKee, and D. S. Ziv. 1973. Experience with cefazolin: an overall summary of pharmacologic and clinical trials in man. J. Infect. Dis.128(Suppl.):S415-S422.","journal-title":"J. Infect. Dis."},{"key":"e_1_3_2_9_2","doi-asserted-by":"crossref","first-page":"961","DOI":"10.1001\/jama.1990.03440070049031","volume":"263","year":"1990","unstructured":"Kernodle, D. S., D. C. Classen, J. P. Burke, and A. B. Kaiser. 1990. 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