{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T14:55:32Z","timestamp":1787496932978,"version":"build-2736575974"},"reference-count":0,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[1979,2,1]],"date-time":"1979-02-01T00:00:00Z","timestamp":286675200000},"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":[[1979,2]]},"abstract":"<jats:p>\n                    A new technique has been devised to investigate the penetration of antibiotics through the gram-negative outer membrane; the application here was to study intrinsic resistance of\n                    <jats:italic>Escherichia coli<\/jats:italic>\n                    K-12. Exponential cells in broth were briefly treated with 2.5 mM ethylenediaminetetraacetic acid at 5\u00b0C to disrupt the outer membrane penetration barrier, and the response of treated and untreated cells to antibiotics was compared by turbidimetry. A barrier index was derived to describe the ability of 7 beta-lactam and 10 other antibiotics to penetrate the outer membrane of strain Y10. There was correlation between the molecular weight and log\n                    <jats:sub>10<\/jats:sub>\n                    barrier index (\n                    <jats:italic>r<\/jats:italic>\n                    = 0.59,\n                    <jats:italic>P<\/jats:italic>\n                    \u2245 0.01). The envelope mutant D22 (\n                    <jats:italic>envA<\/jats:italic>\n                    ) had low barrier indexes for erythromycin, rifampin, ampicillin, and cloxacillin. For the beta-lactams, outer membrane penetration and affinity for inner membrane target site(s) triggering cell lysis were measured as independent components of the overall activity; although penetration and overall activity varied greatly, the affinities of most were within a narrow range.\n                  <\/jats:p>","DOI":"10.1128\/aac.15.2.182","type":"journal-article","created":{"date-parts":[[2012,6,27]],"date-time":"2012-06-27T19:57:02Z","timestamp":1340827022000},"page":"182-189","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":41,"title":["Outer-Membrane Penetration Barriers as Components of Intrinsic Resistance to Beta-Lactam and Other Antibiotics in\n                    <i>Escherichia coli<\/i>\n                    K-12"],"prefix":"10.1128","volume":"15","author":[{"given":"R. Allan","family":"Scudamore","sequence":"first","affiliation":[{"name":"Department of Microbiology and Parasitology, University of Toronto, Toronto M5S 1A1, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Terrance J.","family":"Beveridge","sequence":"additional","affiliation":[{"name":"Department of Bacteriology and Immunology, University of Western Ontario, London N6A 5C1, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Morris","family":"Goldner","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Parasitology, University of Toronto, Toronto M5S 1A1, Ontario, Canada"}],"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.15.2.182","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.asm.org\/doi\/pdf\/10.1128\/AAC.15.2.182","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,2,21]],"date-time":"2022-02-21T18:16:12Z","timestamp":1645467372000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.asm.org\/doi\/10.1128\/AAC.15.2.182"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1979,2]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1979,2]]}},"alternative-id":["10.1128\/AAC.15.2.182"],"URL":"https:\/\/doi.org\/10.1128\/aac.15.2.182","relation":{},"ISSN":["0066-4804","1098-6596"],"issn-type":[{"value":"0066-4804","type":"print"},{"value":"1098-6596","type":"electronic"}],"subject":[],"published":{"date-parts":[[1979,2]]},"assertion":[{"value":"1979-02-01","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}