Comparative study on antagonistic effects of low pH and cation supplementation on in-vitro activity of quinolones and aminoglycosides against Pseudomonas aeruginosa

Abstract

The antagonistic effects of physiological levels of Ca++ and Mg++ on the in-vitro activity of aminoglycosides and quinolones against Pseudomonas aeruginosa were studied at both pH 7.4 and 5.5. Adding Mg++ and Ca++ (100 mg/l) to commercial media deficient of these cations increased the MICs and MBCs of ciprofloxacin and enoxacin four-fold (2 P < 0.01), which was significantly less than the 16-fold increase found for gentamicin and netilmicin (2 P < 0.01). However, the activity of both aminoglycosides and quinolones was similarly affect Show more