{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T15:48:39Z","timestamp":1787759319701,"version":"build-2784847793"},"reference-count":22,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2004,2,1]],"date-time":"2004-02-01T00:00:00Z","timestamp":1075593600000},"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":[[2004,2]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            A sample of 752 resistant\n            <jats:italic>Klebsiella pneumoniae<\/jats:italic>\n            ,\n            <jats:italic>Klebsiella oxytoca<\/jats:italic>\n            , and\n            <jats:italic>Escherichia coli<\/jats:italic>\n            strains from 70 sites in 25 U.S. states and the District of Columbia was examined for transmissibility of resistance to ceftazidime and the nature of the plasmid-mediated \u03b2-lactamase involved. Fifty-nine percent of the\n            <jats:italic>K. pneumoniae<\/jats:italic>\n            , 24% of the\n            <jats:italic>K. oxytoca<\/jats:italic>\n            , and 44% of the\n            <jats:italic>E. coli<\/jats:italic>\n            isolates transferred resistance to ceftazidime. Plasmids encoding AmpC-type \u03b2-lactamase were found in 8.5% of the\n            <jats:italic>K. pneumoniae<\/jats:italic>\n            samples, 6.9% of the\n            <jats:italic>K. oxytoca<\/jats:italic>\n            samples, and 4% of the\n            <jats:italic>E. coli<\/jats:italic>\n            samples, at 20 of the 70 sites and in 10 of the 25 states. ACT-1 \u03b2-lactamase was found at eight sites, four of which were near New York City, where the ACT-1 enzyme was first discovered; ACT-1 \u03b2-lactamase was also found in Massachusetts, Pennsylvania, and Virginia. FOX-5 \u03b2-lactamase was also found at eight sites, mainly in southeastern states but also in New York. Two\n            <jats:italic>E. coli<\/jats:italic>\n            strains produced CMY-2, and one\n            <jats:italic>K. pneumoniae<\/jats:italic>\n            strain produced DHA-1 \u03b2-lactamase. Pulsed-field gel electrophoresis and plasmid analysis suggested that AmpC-mediated resistance spread both by strain and plasmid dissemination. All AmpC \u03b2-lactamase-containing isolates were resistant to cefoxitin, but so were 11% of strains containing transmissible SHV- and TEM-type extended-spectrum \u03b2-lactamases. A \u03b2-lactamase inhibitor test was helpful in distinguishing the two types of resistance but was not definitive since 24% of clinical isolates producing AmpC \u03b2-lactamase had a positive response to clavulanic acid. Coexistence of AmpC and extended-spectrum \u03b2-lactamases was the main reason for these discrepancies. Plasmid-mediated AmpC-type enzymes are thus responsible for an appreciable fraction of resistance in clinical isolates of\n            <jats:italic>Klebsiella<\/jats:italic>\n            spp. and\n            <jats:italic>E. coli<\/jats:italic>\n            , are disseminated around the United States, and are not so easily distinguished from other enzymes that mediate resistance to oxyimino-\u03b2-lactams.\n          <\/jats:p>","DOI":"10.1128\/aac.48.2.533-537.2004","type":"journal-article","created":{"date-parts":[[2004,1,24]],"date-time":"2004-01-24T23:46:39Z","timestamp":1074987999000},"page":"533-537","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":141,"title":["Epidemiology of Conjugative Plasmid-Mediated AmpC \u03b2-Lactamases in the United States"],"prefix":"10.1128","volume":"48","author":[{"given":"M.","family":"Alvarez","sequence":"first","affiliation":[{"name":"Lahey Clinic, Burlington, and Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. H.","family":"Tran","sequence":"additional","affiliation":[{"name":"Lahey Clinic, Burlington, and Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"N.","family":"Chow","sequence":"additional","affiliation":[{"name":"Lahey Clinic, Burlington, and Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G. A.","family":"Jacoby","sequence":"additional","affiliation":[{"name":"Lahey Clinic, Burlington, and Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"crossref","first-page":"809","DOI":"10.1093\/jac\/32.6.809","volume":"32","year":"1993","unstructured":"Arstila, T., G. A. Jacoby, and P. Huovinen. 1993. Evaluation of five different methods to prepare bacterial extracts for the identification of \u03b2-lactamases by isoelectric focusing. J. Antimicrob. Chemother.32:809-816.","journal-title":"J. Antimicrob. Chemother."},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/7.6.1513"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1128\/CMR.14.4.933-951.2001"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.41.3.563"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1128\/JCM.41.2.772-777.2003"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.32.11.1730"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.47.2.559-562.2003"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1128\/jcm.34.4.908-911.1996"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.40.2.342"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.43.7.1669"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(97)07322-4"},{"key":"e_1_3_2_13_2","unstructured":"Maslow J. N. A. M. Slutsky and R. D. Arbeit. 1993. Application of pulsed-field gel electrophoresis to molecular epidemiology p. 563-572. In D. H. Persing T. F. Smith F. C. Tenover and T. J. White (ed.) Diagnostic molecular microbiology: principles and applications. American Society for Microbiology Washington D.C."},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1099\/00221287-88-1-169"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.27.5.715"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.46.12.3837-3842.2002"},{"key":"e_1_3_2_17_2","unstructured":"National Committee for Clinical Laboratory Standards. 2003. Performance standards for antimicrobial disk susceptibility tests 8th ed. Approved standard. NCCLS document M2-A8. National Committee for Clinical Laboratory Standards Wayne Pa."},{"key":"e_1_3_2_18_2","unstructured":"National Committee for Clinical Laboratory Standards. 2000. Performance standards for antimicrobial susceptibility testing. Tenth information supplement. Approved standard M100-S10. National Committee for Clinical Laboratory Standards Wayne Pa."},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.34.11.2200"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.46.1.1-11.2002"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.1128\/AAC.45.11.3189-3194.2001"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1093\/jac\/49.3.557"},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1128\/jcm.20.4.608-613.1984"}],"container-title":["Antimicrobial Agents and Chemotherapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/AAC.48.2.533-537.2004","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/AAC.48.2.533-537.2004","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,2,21]],"date-time":"2022-02-21T18:19:20Z","timestamp":1645467560000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.asm.org\/doi\/10.1128\/AAC.48.2.533-537.2004"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2004,2]]},"references-count":22,"journal-issue":{"issue":"2","published-print":{"date-parts":[[2004,2]]}},"alternative-id":["10.1128\/AAC.48.2.533-537.2004"],"URL":"https:\/\/doi.org\/10.1128\/aac.48.2.533-537.2004","relation":{},"ISSN":["0066-4804","1098-6596"],"issn-type":[{"value":"0066-4804","type":"print"},{"value":"1098-6596","type":"electronic"}],"subject":[],"published":{"date-parts":[[2004,2]]},"assertion":[{"value":"2003-07-24","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2003-10-13","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2004-02-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}