The effects of specific amiloride analogs on Na+ channel and Na+/H+ antiport function in eukaryotic cells have been well studied, but the effect of these agents on Pseudomonas is unknown. The antimicrobial activity of benzamil HC1, 5-(N-N-dimethyl) amiloride HC1 (DMA), 5-(N, N-hexamethylene) amiloride HC1 (HMA), and 5-(N-methyl-N-isobutyl) amiloride HC1 (MIA) on 30 Pseudomonas strains (20 P. aeruginosa and 10 P. cepacia) were compared to amiloride HC1 after a 24-hour incubation in Mueller-Hinton broth at 35 °C. At pH 7.3 the MIC range and MIC50 (in mg/l; MIC50 in parentheses) for amiloride HC1, benzamil HC1, DMA, HMA and MIA were 400 to > 800 ( > 800), 200 to 800 (400), 200 to > 800 (400), 100 to 400 (200), and 100 to 400 (200), respectively, for P. aeruginosa and > 800 ( > 800), 400 to > 800 (800), 400 to > 800 (800), 200 to 800 (200), and 200 to 800 (200), respectively, for P. cepacia. Alteration of pH from 5.5 to 8.5 had a slight effect on potency. We conclude that all the analogs studied were more potent antipseudomonal agents in vitro than amiloride, with the more lipophilic compounds HMA and MIA, having the most profound activity.
Available at: http://works.bepress.com/robert_putnam/111/