{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,3]],"date-time":"2026-05-03T00:19:57Z","timestamp":1777767597805,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2009,9,10]],"date-time":"2009-09-10T00:00:00Z","timestamp":1252540800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2009,9,10]],"date-time":"2009-09-10T00:00:00Z","timestamp":1252540800000},"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>Resistant variants of three clinical Pseudomonas aeruginosa isolates were obtained in the presence of aztreonam. The variants exhibited a four- to eightfold increase in the minimal inhibitory concentrations to \u03b2-lactam antibiotics (except imipenem) to quinolones, such as norfloxacin and fleroxacin, chloramphenicol and tetracycline, but not to gentamicin and polymyxin B. \u03b2-Lactamase production was barely detectable in both wild-type strains and the resistant clones. Only ampicillin, cefoxitin and imipenem increased the production of \u03b2-lactamase, whereas various other \u03b2-lactams did not. Penicillin-binding proteins remained unchanged in the aztreonam-resistant clones. The analysis of the outer membrane proteins did not reveal differences in the outer membrane proteins between the wild-type strains and the aztreonam-resistant clones. Two of the three antibiotic-resistant isogenic clones contained less lipopolysaccharides (LPSs) than their corresponding wild-type strains. Moreover, it could be demonstrated that the ratio of 2-keto-3-deoxy octonate to carbohydrate of the LPS changed in any case between the wild-type strains and the aztreonam-resistant clones. These alterations were accompanied by a decrease in surface hydrophobicity of the resistant clones as compared to the wild-type strains. Therefore, quantitative as well as qualitative alterations in the LPS may provide an explanation for the resistant phenotype observed.<\/jats:p>","DOI":"10.1159\/000238946","type":"journal-article","created":{"date-parts":[[2009,9,11]],"date-time":"2009-09-11T09:12:33Z","timestamp":1252660353000},"page":"82-91","source":"Crossref","is-referenced-by-count":13,"title":["Lipopolysaccharide Alterations Responsible for Combined Quinolone and \u03b2-Lactam Resistance in Pseudomonas aeruginosa"],"prefix":"10.1159","author":[{"given":"H.J.","family":"Leying","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"K.H.","family":"B\u00fcscher","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"W.","family":"Cullmann","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"R.L.","family":"Then","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2009,9,10]]},"container-title":["Chemotherapy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/238946","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000238946","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,29]],"date-time":"2026-04-29T15:42:25Z","timestamp":1777477345000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000238946"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,9,10]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000238946","archive":["Portico"],"relation":{},"ISSN":["0009-3157","1421-9794"],"issn-type":[{"value":"0009-3157","type":"print"},{"value":"1421-9794","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,9,10]]}}}