{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T11:17:54Z","timestamp":1790248674402,"version":"4.1.0"},"reference-count":0,"publisher":"American Society for Microbiology","issue":"3","license":[{"start":{"date-parts":[[1977,3,1]],"date-time":"1977-03-01T00:00:00Z","timestamp":226022400000},"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":[[1977,3]]},"abstract":"<jats:p>\n            Ampicillin-resistant strains of\n            <jats:italic>Shigella dysenteriae<\/jats:italic>\n            type 1 isolated in epidemics in Mexico, Central America, and Bangla Desh were examined for the presence of plasmid deoxyribonucleic acid (DNA) by gel electrophoresis. All strains contained a heterogeneous population of plasmids. Transfer experiments to\n            <jats:italic>Escherichia coli<\/jats:italic>\n            K-12 indicated that the ampicillin resistance determinant (Ap\n            <jats:sup>r<\/jats:sup>\n            ) was located on a 5.5-megadalton (Mdal) plasmid identical in all Shiga strains examined, as judged by DNA hybridization and by its molecular properties. This 5.5-Mdal plasmid contained the ampicillin transposon (TnA) sequences. There was not a high degree of homology between the Shiga Ap\n            <jats:sup>r<\/jats:sup>\n            plasmid DNA and DNA obtained from Ap\n            <jats:sup>r<\/jats:sup>\n            <jats:italic>Salmonella typhi<\/jats:italic>\n            strains isolated from typhoid epidemics in Mexico, previous to the dysentery outbreaks. Although low, the degree of reassociation observed indicated that probably part of the TnA sequence was present in\n            <jats:italic>S. typhi<\/jats:italic>\n            DNA. The DNA hybridization experiments showed, in addition, that there was a high degree of homology among Ap\n            <jats:sup>r<\/jats:sup>\n            plasmids isolated from different enterobacteria, and this identity was confirmed by restriction endonuclease activity. These results together with their similarities in molecular and replicative properties indicate that the Ap\n            <jats:sup>r<\/jats:sup>\n            plasmids, as was suggested for the Sm\n            <jats:sup>r<\/jats:sup>\n            Su\n            <jats:sup>r<\/jats:sup>\n            plasmids, possibly evolved once and then epidemiologically spread in the\n            <jats:italic>Enterobacteriaceae<\/jats:italic>\n            .\n          <\/jats:p>","DOI":"10.1128\/aac.11.3.553","type":"journal-article","created":{"date-parts":[[2012,6,27]],"date-time":"2012-06-27T23:57:02Z","timestamp":1340841422000},"page":"553-558","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":25,"title":["Characterization of an R-Plasmid Associated with Ampicillin Resistance in\n            <i>Shigella dysenteriae<\/i>\n            Type 1 Isolated from Epidemics"],"prefix":"10.1128","volume":"11","author":[{"given":"Jorge H.","family":"Crosa","sequence":"first","affiliation":[{"name":"Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington 98195"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jorge","family":"Olarte","sequence":"additional","affiliation":[{"name":"Laboratorio de Bacteriologia Intestinal, Hospital Infantil de M\u00e9xico, Mexico City, Mexico; and Instituto de Investigaciones en Salud, University of Costa Rica, San Jose, Costa Rica"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leonardo J.","family":"Mata","sequence":"additional","affiliation":[{"name":"Laboratorio de Bacteriologia Intestinal, Hospital Infantil de M\u00e9xico, Mexico City, Mexico; and Instituto de Investigaciones en Salud, University of Costa Rica, San Jose, Costa Rica"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Linda K.","family":"Luttropp","sequence":"additional","affiliation":[{"name":"Laboratorio de Bacteriologia Intestinal, Hospital Infantil de M\u00e9xico, Mexico City, Mexico; and Instituto de Investigaciones en Salud, University of Costa Rica, San Jose, Costa Rica"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria E.","family":"Pe\u00f1aranda","sequence":"additional","affiliation":[{"name":"Laboratorio de Bacteriologia Intestinal, Hospital Infantil de M\u00e9xico, Mexico City, Mexico; and Instituto de Investigaciones en Salud, University of Costa Rica, San Jose, Costa Rica"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","container-title":["Antimicrobial Agents and Chemotherapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/AAC.11.3.553","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/AAC.11.3.553","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,2,21]],"date-time":"2022-02-21T13:54:53Z","timestamp":1645451693000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.asm.org\/doi\/10.1128\/AAC.11.3.553"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1977,3]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1977,3]]}},"alternative-id":["10.1128\/AAC.11.3.553"],"URL":"https:\/\/doi.org\/10.1128\/aac.11.3.553","relation":{},"ISSN":["0066-4804","1098-6596"],"issn-type":[{"value":"0066-4804","type":"print"},{"value":"1098-6596","type":"electronic"}],"subject":[],"published":{"date-parts":[[1977,3]]},"assertion":[{"value":"1977-03-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}