title: The neutralization of antibiotic action by metallic cations and iron chelators.
abstract: The neutralization of the action of a variety of antibiotics on klebsiellae by moderate doses of di- and tri-valent metallic cations, was measured in vitro. Some beta-lactams tested were affected by Mg++ and by Cu++. Of six tetracyclines one was moderately neutralized by Ca++, two by Mg++, three by Cu++, and all, strongly, by Fe+++. Erythromycin was affected by Ca++, lincomycin by Ca++, Mg++ and Cu++. Aminoglycosides were affected by Ca++ and Mg++ and strongly by Fe+++. Five antibiotics (three beta-lactams and two macrolides) with high MICs for klebsiellae were tested against staphylococci: most of the reversing agents were ineffective. The microbial iron chelators, desferrioxamine and enterochelin were largely inactive, affecting only two aminoglycosides.
mesh_terms: D000900:Anti-Bacterial Agents / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002412:Cations / Q000494:pharmacology*; D002614:Chelating Agents / Q000494:pharmacology*; D007501:Iron; D007711:Klebsiella pneumoniae / Q000187:drug effects; D008670:Metals / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D002412:Cations; D002614:Chelating Agents; D008670:Metals; D007501:Iron