{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,3]],"date-time":"2026-05-03T00:08:05Z","timestamp":1777766885051,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2009,9,9]],"date-time":"2009-09-09T00:00:00Z","timestamp":1252454400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2009,9,9]],"date-time":"2009-09-09T00:00:00Z","timestamp":1252454400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemotherapy"],"abstract":"<jats:p>Single and combined resistance to quinolones and beta-lactams was determined after serial transfers of 18 selected strains of Pseudomonas aeruginosa (5), Acinetobacter calcoaceticus (3) and beta-lactamase producing enterobacterial strains (10), in broth dilutions of 4 quinolones and 8 beta-lactams. Two definitions for resistance were used: (I) 8-fold MIC increase and stability of acquired resistance after five transfers in drug-free broth; and (II) 8-fold MIC increase over the breakpoint level. Using definition I, after transfers on a beta-lactam, resistance to one or more beta-lactams was noted in 45%, to one or more quinolones in 7% of strains. After transfers on a quinolone, the frequency of resistance to quinolones was 82%, to beta-lactams 26%. When all tests were counted separately, the resistance percentages were lower, but they showed the same trend. Calculation according to definition II showed quinolone resistance in 5.4% of all tests after transfer on a beta-lactam and beta-lactam resistance in 23% after transfer on a quinolone. Serial transfers on imipenem led to fewer cases of resistance (13%) to beta-lactams than transfers on any other beta-lactam (19\u201339%). There were no conclusive differences between the 7 other beta-lactams.<\/jats:p>","DOI":"10.1159\/000238494","type":"journal-article","created":{"date-parts":[[2009,9,9]],"date-time":"2009-09-09T09:21:59Z","timestamp":1252488119000},"page":"189-196","source":"Crossref","is-referenced-by-count":5,"title":["Combined Resistance to Quinolones and Beta-Lactams after in vitro Transfer on Single Drugs"],"prefix":"10.1159","author":[{"given":"Peter","family":"Mouton","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sophie L.Th.A.","family":"Mulders","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2009,9,9]]},"container-title":["Chemotherapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/238494","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000238494","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T15:37:17Z","timestamp":1777477037000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000238494"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,9,9]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000238494","archive":["Portico"],"relation":{},"ISSN":["0009-3157","1421-9794"],"issn-type":[{"value":"0009-3157","type":"print"},{"value":"1421-9794","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,9,9]]}}}