{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T03:31:22Z","timestamp":1784863882911,"version":"3.55.0"},"reference-count":39,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2011,2,1]],"date-time":"2011-02-01T00:00:00Z","timestamp":1296518400000},"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":[[2011,2]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            Ampicillin-sulbactam is commonly used as an empirical therapy for invasive infections where\n            <jats:italic>Escherichia coli<\/jats:italic>\n            is a potential pathogen. We evaluated the clinical and microbiologic characteristics of bloodstream infection due to\n            <jats:italic>E. coli<\/jats:italic>\n            , with focus on cases that were nonsusceptible to ampicillin-sulbactam and not producing extended-spectrum \u03b2-lactamase (ESBL). Of a total of 357 unique bacteremic cases identified between 2005 and 2008, 111 (31.1%) were intermediate or resistant to ampicillin-sulbactam by disk testing. In multivariate analysis, a history of liver disease, organ transplant, peptic ulcer disease, and prior use of ampicillin-sulbactam were independent risk factors for bloodstream infection with ampicillin-sulbactam-nonsusceptible\n            <jats:italic>E. coli<\/jats:italic>\n            . Among cases that received ampicillin-sulbactam as an empirical therapy, an early clinical response was observed in 65% (22\/34) of susceptible cases but in only 20% (1\/5) of nonsusceptible cases. Among 50 ampicillin-sulbactam-resistant isolates examined, there was no clonal relatedness and no evidence of production of inhibitor-resistant TEM (IRT). Instead, the resistance was attributed to hyperproduction of TEM-1 \u03b2-lactamase in the majority of isolates. However, promoter sequences of\n            <jats:italic>bla<\/jats:italic>\n            <jats:sub>TEM-1<\/jats:sub>\n            did not predict resistance to ampicillin-sulbactam. While the plasmid copy number did not differ between representative resistant and susceptible isolates, the relative expression of\n            <jats:italic>bla<\/jats:italic>\n            <jats:sub>TEM-1<\/jats:sub>\n            was significantly higher in two of three resistant isolates than in three susceptible isolates. These results suggest high-level\n            <jats:italic>bla<\/jats:italic>\n            <jats:sub>TEM-1<\/jats:sub>\n            expression as the predominant cause of ampicillin-sulbactam resistance and also the presence of yet-unidentified factors promoting overexpression of\n            <jats:italic>bla<\/jats:italic>\n            <jats:sub>TEM-1<\/jats:sub>\n            in these isolates.\n          <\/jats:p>","DOI":"10.1128\/aac.00797-10","type":"journal-article","created":{"date-parts":[[2010,12,7]],"date-time":"2010-12-07T06:29:34Z","timestamp":1291703374000},"page":"495-501","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":39,"title":["Clinical Characteristics of Bloodstream Infections Due to Ampicillin-Sulbactam-Resistant, Non-Extended- Spectrum-\u03b2-Lactamase-Producing\n            <i>Escherichia coli<\/i>\n            and the Role of TEM-1 Hyperproduction"],"prefix":"10.1128","volume":"55","author":[{"given":"Rebecca I.","family":"Waltner-Toews","sequence":"first","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David L.","family":"Paterson","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"},{"name":"University of Queensland UQ Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zubair A.","family":"Qureshi","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hanna E.","family":"Sidjabat","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"},{"name":"University of Queensland UQ Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer M.","family":"Adams-Haduch","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kathleen A.","family":"Shutt","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mark","family":"Jones","sequence":"additional","affiliation":[{"name":"University of Queensland UQ Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guo-Bao","family":"Tian","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"},{"name":"Animal Disease Prevention and Food Safety Key Laboratory of Sichuan Province, School of Life Sciences, Sichuan University, Chengdu, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anthony W.","family":"Pasculle","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"},{"name":"Clinical Microbiology Laboratory, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yohei","family":"Doi","sequence":"additional","affiliation":[{"name":"Division of Infectious Diseases, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-0691.2007.01847.x"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkp162"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1089\/sur.2008.0020"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkf069"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.00516-10"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1086\/421495"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkp156"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1469-0691.2007.01849.x"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1128\/AEM.66.10.4555-4558.2000"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/dkp194"},{"key":"e_1_3_2_12_2","unstructured":"Performance standards for antimicrobial susceptibility testing; 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