title: Influence of serum and calcium on the bactericidal activity of gentamicin and carbenicillin on Pseudomonas aeruginosa.
abstract: Because calcium was found to be antagonistic in vitro to the activity of colistin and polymyxin B on Pseudomonas aeruginosa, the effects of calcium and serum on gentamicin and carbenicillin were also examined. Serum was antagonistic to gentamicin in antibiotic tube dilution tests on five strains of P. aeruginosa. Serum was not antagonistic to carbenicillin in tube dilution tests. Physiologic concentrations of calcium antagonized the activity of gentamicin but not carbenicillin. The antagonism observed with gentamicin was less than that previously seen with colistin. The antagonistic effect of calcium and serum was removed by a chelating agent. Gentamicin and carbenicillin may be more active in vivo against P. aeruginosa than colistin or polymyxin B.
mesh_terms: D001770:Blood Bactericidal Activity; D002118:Calcium / Q000494:pharmacology*; D002228:Carbenicillin / Q000037:antagonists & inhibitors; D004492:Edetic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects; D005839:Gentamicins / Q000037:antagonists & inhibitors*; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology*; D007273:Injections, Intramuscular; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010403:Penicillin Resistance; D010406:Penicillins / Q000037:antagonists & inhibitors*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
chemical_list: D005839:Gentamicins; D007106:Immune Sera; D010406:Penicillins; D004492:Edetic Acid; D002228:Carbenicillin; D008274:Magnesium; D002118:Calcium