title: [Effect of cyclic nucleotides on beta-lactamase production and outer membrane proteins of clinical Xanthomonas maltophilia isolates].
abstract: Resistance of clinical Xanthomonas maltophilia isolates to beta-lactam compounds is influenced considerably by the nutrient medium employed for sensitivity testing; the organisms were much more resistant to beta-lactams when susceptibility testing was performed in Mueller-Hinton broth as compared to Isosensitest broth as the nutrient medium. Consequently, the influence of cyclic nucleotides was studied on beta-lactamase expression and outer membrane proteins in more detail. The exogenous supply of 5 mmol/l c-AMP or its lipophilic derivative c-AMP-N6,O2-dioctanoyl resulted in a marked reduction of enzyme production as compared to the control assay; 0.5 mmol/l c-AMP-S or 1 mmol/l c-GMP did not exhibit any effect. The analysis of the outer membrane proteins of Xanthomonas maltophilia revealed the single band of a 40 kdal protein which was expressed independently of the experimental conditions, thus confirming the classification of this pathogen as Xanthomonas maltophilia. The reduction of beta-lactamase expression in the presence of either c-AMP or c-AMP-N6,O2-dioctanoyl cannot be explained at present. The above findings emphasize again the problem of in-vitro susceptibility testing. To avoid false sensitive results, the use of Mueller-Hinton broth is recommended.
authors.affiliation: Institut für Hygiene und Mikrobiologie, Ruhr-Universität Bochum.
authors.forename: W
authors.initials: W
authors.lastname: Cullmann
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000187:drug effects; D003470:Culture Media; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D014974:Xanthomonas / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000187:drug effects
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; C069614:N(6),O(2)-dioctanoyl cyclic AMP; D000242:Cyclic AMP; D001618:beta-Lactamases
vernacular_title: Einfluss zyklischer Nukleotide auf die beta-Laktamasebildung und die äusseren Membranproteine klinischer Xanthomonas-maltophilia-Isolate.