{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T02:37:24Z","timestamp":1773283044194,"version":"3.50.1"},"reference-count":15,"publisher":"Microbiology Society","issue":"4","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2014,4,1]]},"abstract":"<jats:p>A subset of <jats:italic>Escherichia coli<\/jats:italic>, <jats:italic>Klebsiella oxytoca<\/jats:italic>, <jats:italic>Klebsiella pneumoniae<\/jats:italic> and <jats:italic>Proteus mirabilis<\/jats:italic> isolates collected for the Study for Monitoring Antimicrobial Resistance Trends that were positive for the Clinical and Laboratory Standards Institute (CLSI) extended-spectrum \u03b2-lactamase (ESBL) phenotypic confirmatory test (<jats:italic>n<\/jats:italic>\u200a=\u200a3245) or had an ertapenem MIC of \u22650.5 \u00b5g ml<jats:sup>\u22121<\/jats:sup> (<jats:italic>n<\/jats:italic>\u200a=\u200a293), or both (<jats:italic>n<\/jats:italic>\u200a=\u200a467), were analysed for ESBL genes. Most ESBL phenotype <jats:italic>E. coli<\/jats:italic> or <jats:italic>K. pneumoniae<\/jats:italic> possessed an ESBL gene (95.8 and 88.4\u200a%, respectively), and this was 93.1\u200a% if carbapenem-non-susceptible <jats:italic>K. pneumoniae<\/jats:italic> were removed. This rate was lower for <jats:italic>P. mirabilis<\/jats:italic> (73.4\u200a%) and <jats:italic>K. oxytoca<\/jats:italic> (62.5\u200a%). Virtually all ESBL-positive isolates (99.5\u200a%) were cefotaxime non-susceptible [CLSI or European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints)]. Fewer isolates (82\u200a%) were ceftazidime non-susceptible (CLSI breakpoints). In addition, 21.1\u200a% of <jats:italic>E. coli<\/jats:italic>, 25\u200a% of <jats:italic>K. oxytoca<\/jats:italic> and 78.7\u200a% of <jats:italic>P. mirabilis<\/jats:italic> isolates were ceftazidime susceptible but ESBL positive. This suggests that CLSI breakpoints for ceftazidime are too high to detect ESBLs. The lower EUCAST breakpoints detected ESBLs in <jats:italic>E. coli<\/jats:italic> and <jats:italic>K. oxytoca<\/jats:italic> better, but 59.6\u200a% of ESBL-positive isolates of <jats:italic>P. mirabilis<\/jats:italic> were ceftazidime susceptible. For isolates with ertapenem MICs \u22650.5 \u00b5g ml<jats:sup>\u22121<\/jats:sup>, more accurate ESBL phenotype analysis was observed for <jats:italic>E. coli<\/jats:italic> and <jats:italic>K. pneumoniae<\/jats:italic> (sensitivity &gt;95\u200a% for both, specificity 94.4 and 54.1\u200a%, respectively). If carbapenemase-positive <jats:italic>K. pneumoniae<\/jats:italic> were excluded, the specificity increased to 78\u200a%. The positive predictive values for the ESBL phenotypic test with <jats:italic>E. coli<\/jats:italic> and <jats:italic>K. pneumoniae<\/jats:italic> were 97.6 and 81.8\u200a%, respectively, and negative predictive values were 75.9 and 95.2\u200a%, respectively. We therefore suggest that it would be prudent to confirm phenotypic ESBL-positive <jats:italic>P. mirabilis<\/jats:italic>, <jats:italic>K. pneumoniae<\/jats:italic> and <jats:italic>K. oxytoca<\/jats:italic> with molecular analysis.<\/jats:p>","DOI":"10.1099\/jmm.0.068981-0","type":"journal-article","created":{"date-parts":[[2014,1,30]],"date-time":"2014-01-30T03:07:23Z","timestamp":1391051243000},"page":"556-561","source":"Crossref","is-referenced-by-count":15,"title":["Evaluation of the Clinical and Laboratory Standards Institute phenotypic confirmatory test to detect the presence of extended-spectrum \u03b2-lactamases from 4005 Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae and Proteus mirabilis isolates"],"prefix":"10.1099","volume":"63","author":[{"given":"Ian","family":"Morrissey","sequence":"first","affiliation":[{"name":"IHMA Europe S\u00e0rl, 1066 Epalinges, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Samuel K.","family":"Bouchillon","sequence":"additional","affiliation":[{"name":"International Health Management Associates, Schaumburg, IL 60173-3817, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meredith","family":"Hackel","sequence":"additional","affiliation":[{"name":"International Health Management Associates, Schaumburg, IL 60173-3817, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Douglas J.","family":"Biedenbach","sequence":"additional","affiliation":[{"name":"International Health Management Associates, Schaumburg, IL 60173-3817, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephen","family":"Hawser","sequence":"additional","affiliation":[{"name":"IHMA Europe S\u00e0rl, 1066 Epalinges, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daryl","family":"Hoban","sequence":"additional","affiliation":[{"name":"International Health Management Associates, Schaumburg, IL 60173-3817, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert E.","family":"Badal","sequence":"additional","affiliation":[{"name":"International Health Management Associates, Schaumburg, IL 60173-3817, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"345","reference":[{"key":"r1","article-title":"Performance Standards for Antimicrobial Susceptibility Testing; 20th Informational Supplement M100-S20","year":"2010"},{"key":"r2","article-title":"Performance Standards for Antimicrobial Susceptibility Testing; 22nd Informational Supplement M100-S22","year":"2012a"},{"key":"r3","article-title":"Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard, 9th edn, M7-A9","year":"2012b"},{"key":"r4","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkl481"},{"key":"r5","article-title":"EUCAST Clinical Breakpoints v.3. 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